The results also indicate that some .nder pattern algorithms require a white space around the marker, and some do not.

figure 8: Data Matrix (bottom right, rotated) in QR In a second test, the embedded Data Matrix code was positioned in the center of the QR code: .rst without a white border (Figure 9), and then with a white border (Figure 10).


Assuming that some distinguisher D can successfully distinguish D0 from Dm with probability non-negligibly better than guessing, it must be the case that D can distinguish at least one pair of neighboring hybrids Di and Di+1 with nonnegligible probability.

since the di.erence between two neighboring hybrids is simply one transcript of the oneround protocol, this amounts to D being able to distinguish between either two one-round protocol transcripts of accepting executions, or two one-round protocol transcripts of rejecting executions.


Although the number of each account s actions is bounded by wL, without SynchroTrap the total malicious actions remain unlimited if attackers can control an extremely large number of malicious accounts.

synchroTrap limits the total number of abusive actions on a constraint object (e.g., an IP address), irrespective of the number of malicious accounts an attacker controls.


If a suf.ciently subtle attacker with suf.ciently many compromised hosts at his disposal can mimic legitimate traf.c well enough that the victim cannot tell good from bad, there is little that can be done beyond load-shedding, adding server resources, and minimizing collateral damage.

our ultimate goal is that this is the only way to persistently DoS-attack a server, and that routers and client systems are invulnerable to DoS attacks.


IPsec supports end-to-end integrity, using Authentication Header (AH) in Transport Mode.

when AH is used in transport mode, the origin IP address is included in the signature[29].


Thus, the establishment of an in-group indirect key involves an intermediate node, a direct key for the link between the source node and the intermediate node, and a direct key for the link between 0 0 50 100 150 200 Number of compromised nodes for the random pairwise keys scheme to establish an indirect key (not to mention the indirect key that involves only one intermediate node) between two neighbor nodes.

according to the analysis in Section 3.2.3, we know that the probability of having an indirect key between two neighbor nodes is almost 1 for the group-based RK scheme even if there are severe memory constraints on sensor nodes.


ATTACKS AND LIMITATIONS As stated earlier, the approach we take relies on the security properties of the hypervisor to properly isolate our monitoring code from tampering by malicious entities residing in the guest OS s. This assumption is not unique to our solution,and todate,therehasbeennoconcretedemonstration that suggests otherwise.

if the security of the hypervisor is undermined, so too is the integrityand correctness of the transactions we record.


Thus, informative feedback about why access was denied becomes very important if the system is to avoid annoying users with apparentlyarbitrary restrictions.

as mentioned earlier, unrestricted feedback about who is allowed to do what in the system could itself compromise system security and privacy; therefore, policies need to be protected against inadvertent disclosure.


These require the participation of at least k peers to ensure k-anonymity [7, 14].

re lying on other users is not always possible and reduces the autonomy of the system.


One one hand, users wish to evaluate the trustworthiness of online reviews and recommendations and wish to only establish relations with other trustworthy users.

users often wish to remain anonymous and protecttheironlineprivacy.


Taken together, fnet and firc provide enough information to join a botnet in the wild.

in order to mimic an actual bot behavior we need to learn the botnet s dialect (i.e., the syntax of the botmaster s commands as well as the corresponding responses sent by the actual bot).


Proper controls should also be established to guard against individuals bringing children, who are not theirs, to obtain fraudulent birth certificates.

a challenge exists in cases where people die in rural areas and their deaths are not reported to SADHA.


The mesh structure resulting from this procedure already de.nes a set of closed polygons covering the scalar .eld domain.

some polygons may still be very large and non-convex and need to be subdivided further.


Like previous measurement studies Internet worms and botnets, the .rst-hand data o.er tremendous insights into operational dynamics of these malware in the reality.

such measurement data related to malware propagation in online social networks are still not available.


With a high node degree, the network connectivity increases, but the interference between the neighboring nodes increases, and, therefore, the network capacity decreases.

if we decrease the node degree the connectivity decreases, which in the extreme case results in the network being disconnected.


assuming nothing about the TTL .eld except that it is uniformly distributed, then a simple calculation using a variant of this approach shows that the expected number of trials needed to set the TTL .eld to 0x00 and correct the checksum is only 382.


The rightmost (CT) peaks give the round-trip for the constanttime implementation of OpenSSL 1.0.1e, which substantially reduces the vulnerability the curves are almost identical.

they still differ measurably, as row 5 of Table 3 shows the two can still be distinguished with Vmax = 62% probability, while to be completely secure, we should only be able to guess with 50% probability.


Organizations are beginning to carry our forensic investigations in order to identify security weaknesses, improve overall security, prevent future occurrences, and to prosecute offenders [11].

it is very easy to contaminate evidence on a system [1].


Brands system provides ef.cient techniques for proving relations among committed values.

the credentials in that system are linkable for multiple display, whereas the signatures in the EPID scheme are unlinkable.


Since the Morris worm incident, buffer overflow attack problems have been one of the most critical security issues and have been studied extensively.

these vulnerabilities are still the most prevalent type of security problem.


A variation on this idea is to take an unconditional jump to an address .and convert it to an indirect jump through a jump table where the address .appears as the kth table entry.

the table is indexed by the value of an opaque expression that always evaluates to k. the bounds check for the table uses a table size m .k, leading the disassembler to believe that the jump table contains m entries.


Thereafter, each employee can install applications, update the OS, and con.gure critical OS settings.

the OS is monitored and the employees cannot turn o. monitoring.


This policy/rule may work over both the user data items at each end of the dependency, to reach a conclusion with regards to the results.

privacylevels as associated for each involved user data item are honored.


Hence,Figure11showsboththe averageexecution timeoverheadand fractionofL2 cache spaceoccupied by data across MACsizes, ranging from 32 bits to 256 bits.

the.gureshowsthatastheMACsize increases,theexecutiontime overheadforMT increases almostexponentiallyfrom3.9%(32-bit) to 53.2% (256-bit).forBMT,theoverhead remainslow, ranging from 1.4% (32-bit)to 2.4% (256-bit).


Consider a run of the protocol in which all players behave perfectly honestly until the end of the sharing phase, at which point one (unknown) player introduces an arbitrary error.

an honest receiver Ruth, given access to the state of all players, must still be able to recover the shared state.


This showed that our implementation of the embedding process was correct.

in-depth analysis showed that the areas which su.ered distorsion did not have any negative real roots.


This case occurs if LCs start in round 2 or 4 from bit position j, (j =1, 31).

their counting rules consider only the case of j = 1.


Of course, some personal identification methods with properties of touch panels are implemented and used on smart phones such as a single stroke method.

many users lock their smart phones with a simple ordinary four-digit password which can be easily broken Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page.


Anti-Virus (AV) companies commonly rely on signatures, such as strings and regular expressions, to determine malware families, but it is well known that signature-based methods are errorprone and can be easily evaded by intelligent malware programs.

manually reverse-engineering every malware variant to .gure out its lineage requires advanced skills and is often a time-consuming, sometimes even tedious, process.


Second, because of the data sharing on software-based loader balancer, each processing routine needs to acquire a spin lock before getting a packet, resulting in lock contention.

hardware-based approach distributes network traffic directly to the processing queue attached to each CPU core, eliminating the need for spin lock.


However, as Narayanan and Shmatikov [37] point out, active attacks are not scalable because creating thousands of fake user accounts is expensive and this attack may not be as effective in directed graphs when legitimate users do not link back to the sybil nodes.

passive attacks do not actively modify the network.


Practical Faraday cages can be made of a conducting mesh instead of a solid conductor.

this reduces the cage s effectiveness as an RF shield.


In these cases, as the behavior of the illegitimate users becomes more similar to the legitimate user behavior, the detection rate in the .rst time window starts to decrease to 87% and 45% respectively compared to the random attacker case.

it increases signi.cantly as more time windows are processed to identify the legitimate user with detection rates over 90% starting with time window 2 in the informed attacker case and time window 6 in the compromised device case.


Pr (x|si = vj,p) (3) Using Bayesian inversion, the attacker can then transform these probabilities into a vector of aposteriori probabilities Pr (si = vj |x, p).

in contrast to standard template attacks, it is not simply possible to choose the most value for each state byte and combine them, since not all full state vectors correspond to valid encryptions.


In this case, if we reject the action then we are losing some potential functionality since the action is within the bounds of acceptability.

accepting the action without telling the user could be signi.cantly problematic.


3.2 Multi-layer Tree Model The model in section 3.1 is useful when modeling a small company.

when the enterprise scales up, consisting of tens of business goals and hundreds of IT resources, it is neither trivial nor convenient to put all things in a single chart.


Doubling the adversary s bandwidth roughly halves the time to .rst compromise, with the result that at 200MiB/s the adversary fully compromises a user within 30 days with probability 50%.

an adversary that is limited to 10MiB/s ( still more than a typical consumer-grade connection) has a less than 10% chance to compromise a user at all.


The SD captures the trap address and its arguments (passed via registers).

the situation is more complex on an HVM platform.


Unfortunately, attacks that exploit the USB while the victim device is in slave mode are more di.cult to thwart because some of the functionality is required to control the slave device.

smart phone vendors can try to .lter and vet the USB communications using a USB .rewall.


1.1 Related Work Well-known modular-root based signatures (e.g., RSA [21]) are computationally ef.cient at the veri.er side.

these schemes require expensive operations1 at the signer side and have large key/ signature sizes.


The result was encouraging; 92% participants completed the import task.

the login form is optimized to contain only one Sign up with my Google Account button without any other login options, which is not applicable to most RP websites.


All references to function arguments and state variables have a clear meaning.

the standard is ambiguous for setreuid().


Indistributed environments,we canleverageRBAC modelstoenforce .ne-grainedpoliciesforsharing resources[7].

the current cryptosystems do not support such shared modes because the encryption/decryption keys cannot be recognized between RBAC systems.


If u is assigned to l by some slainit rule s2 (in s1 = s2)in.then u remains assigned to l when the body of s1 becomes false (unless this assignment has been terminated).

an slaterm rule de.nes the explicit termination of the assignment of an agent u to a status level l and if the body of any one slaterm rule, that de.nes the termination of u from l,is true in .


They are split in operation and policy .ags as in Table 2.

notall combinations areallowed, topreventinteractionsbetween di.erent algorithms(e.g.,prevent akey to be used for RSA signing and encryption).


A review of 4-valued Belnap Logic For granting access according to some security policy, the traditional Boolean values (tt and f ) are enough: tt grants while f denies access.

when it is necessary to keep some extra internal information about con.icts or irrelevant policies, we need to use some extra auxiliary values.


Second, the seminal Revirt work [7] shows that replayable systems can be built.

revirt is not designed to distinguish secondary attack e.ects from infection-free effects.


This kind of threat is unlikely to cause a great deal of loss to an asset.

a flood or fire which could damage all the assets of an organization is much less likely to occur.


As for VSS, this is the best result one can hope for in terms of poly-time efficiency.

we show a result implying that a reduction of the type we provided to prove Theorem 1 does not exist for MPC, not even if we assume the adversary is passive and static.


Image PassTiles passwords are the same at every login, and as such, are vulnerable to replay attacks.

like other graphical password systems, Image PassTiles is moderately resistant to these accounts because the attacker must devise a methodology for recording the position of the image onscreen as well as recording the location of the clicks.


Our goal offaithfully replicating the client execution on the server can be accomplished by running an instance of the actual full-.edged browser loaded with the application code on the server, one per user, as proposed by Deep.sh [35].

for a popular and complex application, this approach is dif.cult to scale because the browser is a highly memory-and CPU-intensive piece of software.


assume that x 2 = 1 and that |x1||x2| ... |xN |.

applying De.nition 4, we know that w t x[t+1..N]2 e. i=1 |xi|2 1, 11 therefore |xt| v and thus x[t+1..N] 8v .


by the assumption on AW , and, consequently, e-di.erential privacy with expiration window W .

the second sequence satis.es 0-di.erential privacy with expiration window W , since the sequence of outputs up to any time step T is not a function of any xj for j > T - W .


In VIPER, the host CPU veri.es the .rmware integrity of all peripherals one-by-one.

a fasterperipheral on the motherboard canwork as a proxy helper for a slower peripheral.


[1] introduce security tags for data ranges to support memory protection policies, including isolation for a large number of small principals.

the complexity and cost of switching between principals becomes prohibitive as the number of security tags increases.


Inside the logarithm, it would have to be quite large to have any visible e.ect.

since it appears outside and operates on ln N as well, the e.ect of even .= 2 is signi.cant.


The above procedure can be repeated until we reach a point x r (r = n - d, i.e., in at most n - d steps) in which n constraints are activated and where f(x r) = f(x 0).

since in x r exactly n constraints used to specify Q are active we have that x r is a vertex of the polyhedron [4], and therefore there exist an optimal point of the maximization problem that is a vertex of the polyhedron Q.


Remark: As stated in [12], the outputs of two surjective functions H1 and H2 are expected to be uniformly distributed, so that the entire elements of xi and yj could be used.

h1 and H2 do not act as random oracles in our security proofs.


For user authentication over the Internet, one cannot always rely on the existence of hardware at the client side.

behavioral biometrics using human-computer interaction (HCI) can record data from common input devices, such as keyboards and mice, providing user authentication in an accessible and convenient manner.


Therefore we cannot straightforwardly apply the puzzle game to encrypt a picture.

if we modify the rules of the game, it will be nearly impossible for children to recover the original picture.


WARM-UP: HONEST VERIFIER ZERO-KNOWLEDGE It is trivial to construct zero-knowledge proofs when the prover is semi-honest.

it is in some cases interesting to consider a relaxation of zero-knowledge in which the veri.er is semi-honest i.e., where the veri.er follows the protocol correctly but then tries to extract additional information about the prover s witness from the transcript of the protocol.


1.2 Importance of Integrity Browsers indicate to users whenever they access a site over an unencrypted connection.

many users associate encryption with security, and not with con.dentiality.


This example illustrates that labels are a powerful mechanism for enabling application programmers to enforce information-.ow policies.

the example also illustrates that there is a signi.cant gap between the high-level policies of programmers, e.g., that no Worker should be able to send information to another Worker, and the manipulations of labels required to implement such a policy.


In[11,12], the di.erence of movement paths between human players and bots in a .rst-person shooter (FPS) game is revealed and then used for the development of trajectory-based detection methods.

it is unlikely that this type of detection method can achieve similar speed and accuracy in MMOGs, because maps used in MMOGs are much larger than thoseinFPSgames and avatar trajectories inMMOGs are far more complicated.


Dynamically modifying the transmit power of the client may help in minimizing the e.ectiveness of a tracking network as proposed herein, as it will reduce the tracked s broadcast radius.

we have considered scenarios where the broadcast radius is 15m, and still show high potential for tracking.


Because it seems risky to allow the delegate to perform operations without constraint, even if the delegate is named in the resulting principal, we follow the Taos delegation model [33] and require that all delegations be explicitly enabled by the delegator.

the presence of the delegate name in the resulting principal reduces the risk to the point that we anticipate clients routinely and safely enabling delegation in a large class of scenarios where the service is both trusted to handle delegated access checks correctly, and a potential candidate for transparent mediation.


it does not consider the issues our work addresses that of least-restrictive enforcement of the policy.


Java is not yet fully supported in CertShim, as we have not re-implemented our policy engine.

this mechanism demonstrates how our approach can be generalized to work with Java.


This property holds in the path that contains the call to Y .

the SecurityManager is not consulted in one of the paths after Z is called, as the else branch in Z does not consult the security manager.


As a result, we believe that the SELinux model can be used to implement a policy that we can use to verify the integrity of critical phone applications.

the development of SELinux policies to date have focused on de.ning least privilege permissions to contain services.


Overshadow does not protect against these side-channel attacks.

most contemporary cryptographic application code (such as OpenSSL) is designed to resist side channel attacks.


4.2 Registers When the processor starts executing the alphanumeric shellcode, the contents of all the registers is unknown.

in order to do any useful calculations, the value of at least some registers must be known.


In the security analysis approach, fewer security properties can be analyzed ef.ciently, because of the need to analyze potentially in.nitely many reachable states.

the constraint approach requires that the system controls all changes to the RBAC state, because of the need to perform constraint checking.


The obvious drawback of this approach is that some domain names will have a prohibitively large number of similar names (since this number grows exponentially in the length of the name).

some organizations may be willing to pay a premium for the resulting security if their name is small enough to secure in this manner.


Various security measures such as authentication, firewalls, access control, certificates, and data encryption are being used to protect systems against unauthorized access.

as can be gathered from frequent media reports about system break-ins, there is no foolproof technique that totally eliminates all the security loopholes in a system.


To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior speci.c from di.erent mutually distrusting and potentially malicious websites.

javaScript lacks language-based protection and isolation mechanisms and sports several extremely dynamic language features.


Generally speaking, location tracking might be of interest for LTE-based PSN authorities since the .rst responders could bene.t from the information they could receive based on their location.

the threat here is from unauthorized personnel or an outsider attacker.


In addition, she may have to agree on submission of her usage log report to the provider (COB).

the distributor can have rights to collect consumers usage log information.


Traf.c that is not related to C&C communication should be allowed through, to the extent that this is possible without allowing the malware to cause harm.

c&C traf.c should be blocked to trigger backup behavior.


The FastGC framework [HEKM11] was recently extended to read in a description of how circuits are composed from hard-coded circuit building blocks [MZE12].

these techniques do not minimize the amount of memory needed during secure evaluation of the circuit.


For example, API calls typically re.ect the behavior of program code pieces while program strings consist of reused code fragments, author signatures, .les names and system resource information.

di.erent categorization methods have different strengths and may excel at di.erent situations.


The .rst approach is to simulate the ICA attack in suf.cient rounds to .nd a statistically resilient A matrix as the previous work does [9].

a more attack-resilient approach is using the composition encryption scheme (CES) that consists of two steps: transforming the original data with an order preserving encryption scheme Eo .rst; then followed by the basic RASP encryption, which can be represented as follows.


Only a small o.ine ciphertext has to be stored on the sensor node.

other OOIBE schemes require a number of o.ine information which is proportional to the number of messages to be encrypted.


If the segmentation result agrees with the object under test and the trial location, the detached object and its location are deduced.

this brute force attack will not be effective.


As a result, the code that manipulated page tables needed to be added to the monitor in the hypervisor.

the logic to examine the pages and perform lookups in the known binary database are implemented as user processes in the Patagonix VM.


The results show that EARDet detects attack .ows with a 100% detection probability, which con.rms Theorem 4.

figure 5(b) shows that FMF cannot catch most of the Shrew .ows.


The NXT records identify what does not exist in a zone to avoid generating signatures on general statements of nonexistence which could be replayed.

notice that an attacker could query for the NXT record of a domain name to .nd the next domain name in canonical order and repeat the process to learn all the domain names in the zone.


Hosting an encrypted .le system with ACLs in a Cloud VM, backed by the persistent Cloud storage, is also possible.

such .le systems are usually meant for protecting data from unauthorized users with physical access to the disk rather than as a means to enforce privacy across multiple users.


The standard explicitly allows processes without appropriate privileges to set the e.ective user ID to any one of the current real, e.ective, or saved user IDs.

the EPERM condition speci.es that an attempt by processes without appropriate privileges to set the e.ective user ID to any value other than the real or saved user ID is an error.


IDENTIFYING NON-LINEAR BEHAVIORS The aforementioned timeline graphs are motivated by the idea that most application protocols describe a linear progression of messages from the start of a connection to its .nish.

many protocols, particularly those designed for human interaction, allow for much more free-form behaviors which may be highly non-linear.


Over the last years, denial-of-service attacks on wireless local area, ad-hoc and sensor networks have widely been analyzed [2,13,14,20], and various countermeasures for their detection and prevention have been proposed [8, 9, 20, 27, 29].

all these countermeasures rely on secrets that were pre-established between sender and receiver(s), or are very speci.c regarding the attacker s capabilities and the considered scenarios.


The proposed approach is protocol speci.c.

not all the deployed smart grids are using this protocol for communication.


If the x-dimension of the block size is set to 32 (to equal the warp size), an iteration of the loop at line 7 is sufficient to process most input characters.

such setting leads to warp underutilization.


By issuing the command fastboot oem unlock,the device will display a warning page and once we click yes , it is o.cially unlocked and the manufacture warranty also is voided.

this is far from being inconspicuous and requires user input.


This is because misbehaving UEs do not start generating attack tra.c until a suitable state transition occurs, which happens only after the UE sends or receives normal tra.c.

the e.ect of the end of the storm is immediate, and queueing times very quickly drop to normal levels as the RNC serves the queued signalling messages.


The most popular CAPTCHA is a method to read distorted letters.

it is analyzed by computer software according to developing OCR technology.


The attestation token therefore consists of all information that is necessary to validate the freshness of the attestation response: t = {Na0, time0}-1 , Cert(AIK) (7) K TTP {hv s (Na0), v, PCR,g mod p} -1 K AIK The attestation token introduced here has similarities to the one introduced in [14].

the main di.erence is that a veri.er can validate the platform con.guration without requiring the prover to perform expensive TPM operations.


Based on the decaying correlation structure present in anomaly scores, we argue that a stochastic model of a few previous scores can be used to accurately predict future scores.

to constrain the complexity of threshold adaptation, we must answer the following question: How many past anomaly scores are needed to accurately predict the next score?


Binary analysis showed that tElock uses an undocumented opcode, F1, which causes interrupt vector 1 to be issued by the processor on normal hardware.

inQEMU, thisinstructionhad the effect of freezing the entire guest OS, rendering the guest unusable even when tElock is executed from guest userspace.


The operational code uploaded by the attacker during the bootstrap phase could be very large in principle, and could perform the attacks described in Section 3.

since the focus of our evaluation was on the initial exploit and bootstrap phases, we could do with a code size of about 200 bytes for a proof-of-concept operational phase.


The empirical probabilities of the bot pressing a key every 1 or 5.5 seconds are signi.cantly higher than their neighbor intervals, which provides us some insightsinto theinternals of thebot: it usesperiodic timers to poll the status of the avatar(i.e., current coordinate), and issue keyboard commands accordingly (e.g., bypass possible obstaclesby turningleft/right andjumping).

for human players, their keystroke intervals follow a Pareto distribution, which matches the conclusions of previous research [53].


On the other hand, 8 is the fourth most frequent number in Company A s password constitutions, because the pronunciation Table 2 Character frequency distributions of English plain texts, western passwords, Pinyin texts, and Chinese Passwords Latter A BCDE FGHI J KLMN OPQRSTUVW XYZ Western_PWD 9.34 3.11 3.79 3.69 9.52 1.71 2.75 3.05 6.23 1.16 2.38 5.07 3.66 6.04 6.84 2.75 0.37 6.90 6.41 5.25 2.99 1.22 1.65 0.89 2.38 0.85 China_PWD 9.73 2.38 3.21 2.81 5.24 2.13 4.76 4.95 8.05 2.94 1.61 4.73 2.59 8.00 4.65 1.48 2.47 1.94 3.93 2.43 3.98 0.98 3.87 3.24 4.63 3.25 is similar to making fortune.

8 is the much less frequently used number in Burnett and Kleiman s data for western users passwords [2].


The identity provider solutions have a solution, in that identity providers can sign the attributes.

this implies that there are sites out there that are trusted to assert all the needed attributes for a user, that the user has some mechanism for authenticating to those sites and requesting the signed attributes, and perhaps hardest of all there is some infrastructure in place that enables users to find them.


However, a jammer using higher power will further decrease the PDR value and increase the SS measurement, thus pushing the resulting (PDR, S S) pair further towards the upper left corner, making it more distinct the benign-region.

a jammer that operates on a lower power level is not as e.ective in interfering with the network operations.


Existing TOG-based secure CDC solutions can work in compatibility with SAFE, providing backward compatibility.

to this end, we recommend that adapters be developed to meet speci.c organizational needs.


has no access to the source code, can focus their e.orts on modi.cations where vulnerabilities are most likely to be introduced, thereby signi.cantly reducing the time and e.orts needed to audit a phone.

providing such functionality is a challenge.


Additionally P2 sends the keys for the input wires corresponding to its own input y and a NIZK proof to prove that the garbled circuit is correct and the keys sent in the OT are consistent with the circuit and P2 s input.

this solution is very ine.cient as it requires non-black-box use of the underlying primitives.


One solution would have been to implement everything in one sensor, and have the sensor determine the location and values of the arguments itself.

by doing this, we found that our sensor essentially ended up duplicating the code that the kernel uses to locate and copy the arguments from the calling process to the new process.


Implementing tamperproof interfaces into the drive appear contrary to the marketplace desires for inexpensive, highperformance storage.

building additional security into the drive enclosure in a similar manner to the IBM 4758 secure co-processor [12] is a design point that is only feasible to achieve if the cost-bene.t ratio for a speci.c application dictates it to be appropriate.


This paper and previous work show that the main weakness of social-based authentication schemes is that the knowledge needed to solve them is too public: Ironically, the purpose of social networks and the nature of human beings is to share knowledge.

we believe that SA tests could be more secure yet still solvable by humans.


On one hand, in the HbC model, Bob is assumed not to deviate from the protocol, which should rule out this guessing attack.

while HbC is clear with respect to participants scrupulously following all protocol steps, it is somewhat murky with regard to the validity or goodness of participants input.


In fact, time of day as an access control input is used as an example in Saltzer and Schroeder s classic 1975 paper [29].

that work puts it in the category of arbitrary user-de.ned sharing controls, or protected subsystems, an idea which never gained much traction.


For example, both e-topology and the influence factors of two servers, it is commerce.server.id1and e-commerce.server.id2 are out of secure straightforward to discover that e-commerce.server.id1 should be states because of recent updates of vulnerabilities.

only patched first because it has higher weight and vulnerability impact.


3D CAPTCHA explores the human s 3D spatial cognition abilities to differentiate from a machine.

recent work demonstrates an approach to break 3D text CAPTCHA with a sequence of some offline processing techniques as described in [4].


However, nShield can learn if a collision has occurred by overhearing the tra.c from the initiator, and act accordingly.


Thus, schema validation against this XML Schema would not be alarmed by any of the attacks presented in Section 3.

given a hardened XML Schema that closely matches the intended SOAP message structure, XML Schema validation would have detected the additional bodies in the Amazon messages of signature wrapping attacks of type 1 and 2.


As there is no ground truth to compare against, these are hard to evaluate.

as we use permissions as a starting point and then add a signi.cant amount of additional data, it is necessarily more complete than the permission system.


It requires reprogramming transponders and locks once, which is often done in a regular manner anyway.

the availability of only three locking system slots can make the separation of one big locking system di.cult.


Traditionally, malicious code targets system utilities, popular network services or components of the operating system.

in a continuous e.ort to become more persistent and avoid detection, the target of the infection has shifted from software components towards more low-level elements, such as bootloaders, virtual-machine hypervisors, computer BIOS, and recently even the hardware itself.


The authors in [3] have also applied hierarchical clustering approach to form malware clusters considering similarity scores generated after applying Jaccard index.

we utilized DTW distance scores as points in hierarchical clustering as our system call traces are dynamically generated and to capture the similarity within these traces a dynamic algorithm is required.


He is able to eavesdroponany communication in the network, tocompromise individual sensor nodes and capture all information inside it, and to inject fake packets to sensor nodes nearby.

we assume the base station is rich in computing resources and is securely projected.


This would allow the content distributor/rights issuer to identify domains and monitor content usage patterns.

such a situation, which seems unlikely, can be avoided by using two payment cards, one for managing the domain and the other for buying content.


For instance, a language handling uncertainty in the environment might use the XACML decision Indeterminate, in order to represent that something unexpected occurred, or a language requiring an explicit notion of con.ict might use the decision T, as de.ned in PBel [7].

this multiplicity of decision sets raises several issues.


between resiliency against packet-dropping and robustness to a node compromise.

encryption with a cluster key provides an intermediate level of robustness to a node compromise [24] (a compromised node can overhear only its immediate neighborhood), and also supports local broadcast (i.e.


For card-not-present transactions (e.g., ecommerce), it would be easier for a user if she has access to a chip-card reader(e.g., the user can avoidtyping inthe secret key).

users can still use a personal device (with appropriate software on it) for generating localized ID numbers.


His work is based on restrictive blind signatures and divertible proofs, and allows credentials to be issued to users under pseudonyms, so that they can obtain additional credentials based on existing ones.

the protocol does not allow for credential revocation.


These measures cannot completely guarantee that the malware will not cause any harm (0-day attacks in particular are hard to block).

experience from the Anubis deployment shows that they are in practice suf.cient for the safe operation of a malware analysis sandbox.


Upon receiving the wipe-out command, the smartphone initiates the data erasure.

if the state of the phone is normal, the network will send a call accepted message to the smartphone consistent with the access permission for a legal ongoing emergency call originated by a smartphone without the SIM card.


The deviation measure alone would be appropriate in a lossycompression scenario.

it is inappropriate for access control data since it also accounts for the coverage of exceptional and wrong assignments.


This prior literature thoroughly documents users privacy concerns about sharing location data.

smartphone operating systems provide applications with the ability to access a number of resources beyond location data.


6.3 Effects of Sibling Information Our results indicate that using sibling categories statistically significantly improves the F1-measure by up to 14.61% on the 20NG dataset and by 10.33% on the ODP46 dataset for the short queries.

our results indicate that using sibling categories does not improve F1-measure for the long queries.


It was beyond the scope of this paper to optimize the worm for the latency topology of the Internet, since we do not have latency data from all points of the Internet to all other points with which to assess such optimizations.

it is reasonable to suppose such optimization would speed up the worm a little more.


It is clear from the current use of Orbot, that the Tor network can be successfully accessed from mobile devices.

the results from our study provide an early indication of the e.ectiveness of operating Tor within a truly mobile context, and of the signi.cance of the performance impact, introduced by roaming, on a mobile Tor user and/or the wider Tor network.


For example, a malicious cloud can simply publish its states and protocol views on a public website.

we do guarantee that as long as there exists at least one honest cloud, a malicious cloud cannot learn any information about the client s logical access patterns.


They also extend their approach to hybrid settings in which key distribution centers (KDC) may be available.

all of the above schemes are mainly targeted at DSNs deployed in a geographically limited area.


For example, suppose that a peer A receives t claims against another peer B.When employing the direct identity validation method proposed in [17] against Sybil attacks, A should .rst challenge all the t witnesses who generated the claims to perform some task that can only be completed by t real-world users before asserting that B is malicious or sel.sh.

in SDT, the identities of the witnesses are unknown due to the requirement of witness anonymity.


S then the proof is very similar to that from the traitor tracing system of [6].

if s =1 and (i, j) ./S then our simulator will need to generate the key Ki,j for the adversary and still simulate the challenge ciphertext.


[17] can detect privacy leaks by using a dynamic taint-tracing method.

it uses a passive detection method, which needs to know the conditions of triggering privacy leaking behaviors in advance.


Understanding the e.ect of a set of policies on a changeable database state has already been shown to be undecidable.

we can simplify the problem if the policies impose limits on the kinds of changes an untrusted user may make.


We .rst considered assessing its resilience against commercial malware detectors by using real malware samples that were modi.ed to implement some of their functionality in side e.ects.

as pointed out in [12], this type of evaluation would be of doubtful value.


However, prior research shows that the users do not pay too much attention to the permission list when installing apps, and the developers tend to declare more permissions than needed [25].

the traf.c usage data generated by some applications (e.g banking applications) is exceptionally sensitive, at a degree that the app developer might not want to divulge them even to the legitimate data monitoring apps.


There are also some centralized publish/subscribe systems where similarly a single node collects all published information before disseminating them.

it is hard to tell which node is responsible for which type of alerts, especially for unknown attacks.


due to the unenforceable nature of obligations, a system can never guarantee that an obligation will be ful.lled.


Consequently, the number of entries for .le data regions becomes only 2.318.

in the FAT and directory entry regions, a sector contains several regions to be protected, and this expands the size of the policy.


The naive Bayes and Bayesian network yield nearly 100% accuracy of .nding the root-triggers, both of which are not very sensitive to the cost matrices.

the accuracy of SVM increases signi.cantly with increased false negative penalty in the cost matrix.


Systems that take this approach have the potential to outperform systems that perform training at a single level.

the relationships between multilevel training, the adversary s domain knowledge, and secrecy are not yet well understood.


The ISO/IEC 15118 standard is ascribed that incorporates X.509 PKI solution for V2G network.

as traditional X.509 based PKI for V2G network has several shortcomings, we have proposed an effectual PKI for a V2G network that is built on based on elliptic curve cryptography and self-certified public key technique having implicit certificate to reduce certificate size and certificate verification time.


We observe that around 97% of the users have more than 11 categories, and 70% of the users have even more than 14 categories.

in order to avoid being detected, an intelligent attacker may randomly rate a small fraction of pages from many other categories.


Without a formal semantics, the implications of such composability would have been unclear, and its correctness suspect.

in our .nal semantics, given below, it is straightforward to see that the TMI security policy enforcement guarantees are always correctly maintained.


A larger overlap will result faster execution but coarser boundaries .. WM capacity Execution time (s) Encoding Decoding 1 0.296 0.259 2 0.292 0.255 3 0.285 0.271 4 0.306 0.283 5 0.307 0.288  ..

the selected window size here is less than 1/20th .


4.4 AspectJ Correctness As mentioned in the introduction, the process of inlining the generated AspectJ code into the program is outside the boundaries of JavaMOP, and thus JavaMOP makes no guarantees that the actual weaving of the AspectJ .le is done correctly.

it is worth highlighting that there are some security concerns that arise in the AspectJ-weaved code (for example, in AspectJ5 for a privileged aspects to access private class members it introduces into the target class a public method to get and set the private member) [13].


After the encryption transform, all remote reads occur on public variables (except for the key variables of D and E).

the transform does not affect any con.dential variables assigned at the same host, or pc, variables, for instance.


These attacks can use any side information.

the server is trusted to compute the aggregate statistics correctly: this is its goal.


Therefore, care should be taken in constructing cardinality constraints based on them.

for example, the function .2eval(¬active( u , r, t )) refers to a set of roles that are not active in any of user u s sessions at time t. Hence, |.2eval(¬active( u , r, t ))| = n states that the number of roles not active in any of user u s sessions at time t cannot be more than n. it is not clear whether it is n out of those that u can activate or that are in R. Depending upon application, distinction may need to be made a priori.


Three examples of recent browser security features are HttpOnly cookies [2] that enable web developers to specify cookies that should be inaccessible from JavaScript, X-Frame-Options [21] to enable web developers to prevent their pages from being framed, and JSON.parse() [1] to enable web developers to deserialize JavaScript Object Notation (JSON) text safely without executing JavaScript code.

web developers have been slow to use these new browser security features [30, 26].


In fact, t +w degree is enough for the masking polynomial h(x).

at the setup stage, the group manager does not know the exact number of revoked group members in a particular session.


This style of repeated scanning using DFA is commonly used in language parsers.

it is inefficient for packet payload scanning where the chance of the packet payload matching a particular pattern is low (such inefficiency is verified in Section 0).


Virtualization has the potential to enable novel services, such as security via VM introspection [6, 18], migration [8] and checkpointing.

the adop tion of such services in modern cloud infrastructures relies heavily on the willingness of cloud service providers to deploy them.


The provider of the original software holds the best position to serve as the role of trusted veri.er for certifying the property of the customized software.

when the original provider is not trusted or not available, a trusted third party can be employed and it should maintain a repository to store the property information of all known-good source code, which may come from di.erent software providers, another trusted third party or trusted agent for software certi.cation.


Writing the send entry is the tricky step, because the sender needs to know the identi.er of the remote receive queue.

the sender and receiver may not have any shared information which can be used to agree on an identi.er, so the cleanest solution is for the sender to choose an identi.er for the remote receive queue and transmit it along with the .rst data packet.


As discussed in section 4.2, HyperSentry handles this case successfully.

if the queued interrupt causes a VM exit directly after returning from the SMM, the .rst instruction of the VM exit handler, rather than the injected CPUID, will be executed before the performance counter over.ows.


A similar lemma can be shown in the case of public-key encryption, if a is smaller by a v factor of n log q.

in our optimal FHE scheme in Section 4, we will only need to invoke this lemma with secret-key encryption.


Attribute based access control approaches [7] provide enhanced .exibility compared to the previous mentioned access control models, by utilizing a number of security related characteristics of subjects and objects, which are expressed in the form of attributes, in order to provide .ne-grained access control.

modern computing environments require the utilization of a number of factors for the creation of the access control decision.


This considerably increases the total proof size to 3000 bytes.

in DVS, the server combines the signatures of all the machines into a single one, always maintaining the communication cost of 10 bytes.


This de.ciency can be recti.ed using Access Control Lists (ACL) on Linux.

this interferes with normal use of .le permissions, e.g., a manual permission change can negate the ability of untrusted code to access user .les.


A natural way to address these privacy concerns is with application permissions in the operating system.

continuous sensing and natural user input pose new challenges to access control design.


As mentioned above, the adaptiveness accommodated by Assumption 2 may be slightly weaker than the adaptiveness accommodated by Assumption 1.

under Assumption 2, the NBUE property brings a certain other degree of adaptiveness.


For example, 28 of 29 users (97%) granted the foursquare app (in which users check in to various locations nearby) access to their location, a similar approval rate to that of Maps.

40 of 68 users (59%) who had installed the IMDb app (which can use location to display nearby movie showtimes) granted it access to their location, and Shazam (which allows users to tag where they heard a song) was granted access by only 53% of users.


It is important to note that only the proposed construction enjoys the desirable property of match-then-decrypt, and hence can be used to alleviate the computation burden of users in the attribute-based setting.

it is indispensable for receivers to perform attribute matching detection (i.e., decryption test) in attributebased setting.


CAs are replaced with notaries, trusted third parties that are incentivized to be trustworthy agents due to trust agility, the ability of the user to change who their trusted notaries at any time.

multi-path probing cannot validate all domains.


SecVisor ensures integrity of the code executing in privileged mode, thereby preventing unauthorized kernel modi.cation.

our system protects user-mode application s data secrecy, not the kernel integrity.


As seen in the other web applications, the entropy values (Table 3) decrease drastically as the threshold is decreased.

we can observe that simply decreasing the threshold does not guarantee a repre- Figure 8: Performance of our Classi.er.


Many situations in security have a similar structure, such as when password requirements are too complicated [28].

there is an additional problem in security, which is the often required treatment of others as enemies.


Inparticular,the colludingparties couldlearn which(letters,positions)ofthe patient sDNAare speci.edin fp.

this can occur onlyfor the portion of the .ngerprint matching the patient s genome.


properties which do not impose heavy computations.

there is a need for several identical databases which should not be communicating with each other at all; otherwise, the privacy of the information can be breached.


PF_RING exports a shared memory of packet rings in kernel to user-level applications, and its direct NIC access (DNA) extension allows the NIC to move packets to ring buffers directly without CPU intervention.

each thread can bind on no more than one RX queue with DNA.


The resulting scheme would be somewhat more e.cient.

it would require tighter integration between our code s representation of bignums and the application s routines for extracting entropy from passwords, a requirement we deemed inadvisable.


Detecting modi.cations to the kernel text area and static data areas can be accomplished with a hash.

the adore-ng rootkit targets the Linux VFS data structures that are dynamically created in kernel data [8].


Our results demonstrate that software quality, as measured by the number of issues, issue density or number of exploitable bugs, does not always improve with each new release.

generally the rate of discovery of exploitable bugs begins to drop three to .ve years after the initial release.


The predominant .rst-line of defense against scripting vulnerabilities is sanitization the process of applying encoding or .ltering primitives, called sanitization primitives or sanitizers, to render dangerous constructs in untrusted inputs inert [1, 38, 49, 50].

the practice of manually applying sanitizers is notoriously prone to errors [1, 27, 33, 41 43].


Although most of the hardwarebased approaches were based on snapshot analysis, there was an approach that employed event-driven integrity monitoring [24], which has some similarities to the snoop-based monitoring.

it was a hypervisor-based approach which is not a perfectly safe execution environment as we mentioned.


However, after Alice discloses A1 .B1, from Bob s point of view, he will .nd a circular dependency between A1and B1, which may make him believe that there is no hope to establish trust, and terminate the negotiation prematurely.

the policy migration in the second example does preserve the potential success of the trust negotiation.


theattacker canperform some maliciousactionstoruinthereputation oftheimpersonated App.


Even in these simple cases, it may not be straightforward to .nd a solution that minimizes the recon.guration cost and at the same time prevents the attacker from reaching the goal.

by exploring the dependency relationships among vulnerabilities, the minimum-cost network hardening approach in [15, 31] can compute optimal solutions based on the given attack graphs.


Actually, gn+1 is not really required, but the xi' s would be enough to break the semantic security, and thus cannot be public either.

the broadcaster does not need to know a, .


BitVisor: A Thin Hypervisor for Enforcing I/O Device Security Takahiro Shinagawa Hideki Eiraku Kazumasa Omote University of Tsukuba Kouichi Tanimoto Japan Advanced Institute of shina@cs.tsukuba.ac.jp University of Tsukuba Science and Technology {hdk,tanimoto} @osss.cs.tsukuba.ac.jp omote@jaist.ac.jp Shoichi Hasegawa Manabu Hirano Kenichi Kourai Takashi Horie Toyota National College of Technology Kyushu Institute of Technology University of Tsukuba manabu@dsl.gr.jp kourai@ci.kyutech.ac.jp {s-hase,horietk} @osss.cs.tsukuba.ac.jp Yoshihiro Oyama Eiji Kawai Kenji Kono University of Electro-Communications Nara Institute of Science and Technology Keio University oyama@cs.uec.ac.jp eiji-ka@is.naist.jp kono@ics.keio.ac.jp Shigeru Chiba Yasushi Shinjo Kazuhiko Kato Tokyo Institute of Technology University of Tsukuba University of Tsukuba chiba@is.titech.ac.jp yas@is.tsukuba.ac.jp kato@cs.tsukuba.ac.jp Abstract Virtual machine monitors (VMMs), including hypervisors, are a popular platform for implementing various security functionalities.

traditional VMMs require numerous components for providing virtual hardware devices and for sharing and protecting system resources among virtual machines (VMs), enlarging the code size of and reducing the reliability of the VMMs.


We intuitively expected to see a performance advantage of our untrusted-naming implementation over trusted directories.

this is not the case if VPFS was con.gured to use its lookup cache.


In general, the distributions of attacks among ASes is of similar shape for the darknet and the home network, while the university encounters an enhanced and widened distribution of attacks.

attack statistics from the mobile network are signi.cantly narrowed.


Of course, we could generalize the unit even further by making unit delimiters and maximum unit size part of the Spec, beyond bytes and space-delimited words.

we have not yet found this to be necessary for the handful of protocols we have examined.


Intuitively, when the .ngerprint universe is signi.cantly larger than the observation epoch, one expects a .ngerprint to appear at most once in background traf.c.

.ngerprints corresponding to worm packets should appear with a frequency determined by the number of worm packets observed in the observation epoch.


Content .ltering monitors data transferred across an enterprise s network boundary to detect possible con.dential information leakage.

this technology is weak with respect to encrypted packets and is therefore mainly for accidental leakage rather than malicious theft.


Finally, impact from the data burden for using Tor, was excluded from the initial modelling, as the primary focus of the study, was to assess the impact of mobility speeds and time to recovery.

the Guardian Project previously estimated a data burden of between 15% and 46%, from using Orbot [24].


As shown in [3], bounding the default paths to a small constant in general leads to larger D2FAs than if we allow the depth to become large.

small depth D2FAs will have relatively small content labels.


The average time for a single challenge-response pair is 2 Note that the time for computing six checksum blocks on the NIC is longer than the time of the theoretical fastest proxy attack described in Section 5.4.1.

it is much shorter than the time of the real proxy attack we have implemented.


The main idea is that a single consultant should not have access to information about two corporations that are in competition with one another because such information creates a con.ict of interest in consultant s analysis.

the consultant is free to advise corporations that are not in competition with each other.


Among existing user authentication mechanisms, passwords are still the most pervasive due to their signi.cant advantage in usability over other alternatives such as smartcards and biometrics [28].

password-based user authentication has intrinsic weakness in password leakage, which may lead to .nancial loss or corporate data disclosure.


Deception is particularly powerful in IW.

unsuccessful deception could backfire and get punished.


Well-written information security policies, specifically data retention and acceptable use policies, can help protect the business.

these policies will lose their meaning and power if they are not enforced routinely and consistently, regardless of who violates them.


First, process checkpointing (e.g., Flashback [15]) has been researched for many years.

rolling back the attacked process to the latest pre-attack checkpoint could result in the inconsistency among interactive processes, and the infection e.ects caused by the attack is not repaired.


In KP-ABE, as in Fuzzy IBE, each ciphertext is labeled by the sender with a set of descriptive attributes.

each private key is associated with an access tree that speci.es which type of ciphertexts the key can decrypt.


A ret instruction can be encoded with any of the 0xc2, 0xc3, 0xca or 0xcb bytes, and, as such, can be part of any of the instruction .elds (excluding the pre.xes).

jmp*/call* instructions are encoded by two-byte opcodes: an 0xff followed by an ModR/M byte carrying certain three-bit sequences.


Again, due to the existing protection in the power grid, this is non-trivial.

assuming that this is impossible will de.nitely give us a false sense of security and may pave ways for catastrophes in the future.


In this instance, the design flaw was not a mistake of CCHIT's certification criteria, but instead an oversight by the developers of ProprietaryMed.

note that the test script only asks for an explanation of how the system performs logging and does not require a demonstration or a testable oracle that demonstrates auditable logs.


Finally, their proposed model integrates time-bound access control of EHR data with rolebased access control using personalized and customizable time windows.

in these approaches, the data owner does not keep a copy of the data and when access control policies change, the data owner has to download and decrypt the data, re-encrypt it with the new keys, and upload the encrypted data.


Since imprecise protocols (i.e., the bucketization approach) do not reveal true access pattern due to the presence of false positives, they are much more resistant to the access pattern based inference attacks.

bucketization approach reveals the bucket identi.ers to an attacker.


Estimating the error is part of our future work.

most of the addresses belong to the same IP range/origin AS (cf., also [2]) and thus do not a.ect our observations.


With a total turnaround time of about 5 seconds between GPRS Attach commands (3 second response time + 2 second command interval), GPRS Attach has a output rate of roughly 0.2 commands per second.

as only one in .ve attach commands reach the HLR, the throughput is further reduced by one-.fth, to 0.04 commands per second.


These policies enable a simple treatment of security, and they can often be veri.ed by typing.

their enforcement in concrete systems involves delicate compilation issues.


Section2) thereisnoef.cientandeffective solution to transparently authenticate a user while she answers (or places) a phone call.

we argue that it is possible to use the values obtained from the accelerometer and orientation sensors (whilethe user answers,or places,acall)asa biometric measurein order to authenticate the user.


Note that one way to prevent the scenarios depicted in Figure 4(a) is to consider that r1 is in conflict with all the roles hierarchically superior to r2, as in [8, 14].

this approach is very restrictive, and makes the task of properly designing a role hierarchy very difficult.


This approach is also reasonable as access purposes can be granted to the tasks or functionalities over which roles are de.ned within an organization.

using an RBAC mechanism for the management of both access permissions and access purposes may increase the complexity of the role engineering tasks.


[37] to perform authentication with IdPs directly in the browser, and convey the authenticated identity to RPs.

as the websites in our study had not yet adopted the protocol extensions, doing so would have forced us to use di.erent IdPs and RPs for subsequent studies.


Out of the 13,811 APIs that those applications use, only 158(1.1%) are undocumented.

the same applications use 292 API calls that require permissions, out of which 22(7.5%) are undocumented.


Alternatively, one could directly extend the Objective-C runtime and frameworks with dedicated interfaces that validate whether the caller has the appropriate privileges (similar to the Android permission system [18]).

the iOS Objective-C runtime and frameworks are closed-source.


In certain applications, this could lead to delivering emails to unintended recipients.

we believe such attacks are application-speci.c and dif.cult to launch.


To enlarge the analysis scope, our Application Driver utilizes several key features of Android, such as component-based programming model, event triggers.

our technique alone could not guarantee all possible behaviors are captured within the short time an app is executed.


The only requirement is that by the time the branch is executed, it must evaluate to the address of the dispatcher, or to another gadget that leads to the dispatcher.

the attack does not rely on speci.c operands for each of these branches: functional gadgets may change the CPU state in order to make available a di.erent set of gadgets for the next operation.


It is true that RSUs can trace Vi s path based on the credentials if they are used frequently and at di.erent locations.

in our scheme, Vi only uses its credential explicitly occasionally (only when it wants to obtain the updated system master key s).


For each client, prediction generates a capability that authorizes access to all shared .les and capabilities for all four non-shared .les.

unix grouping generates one capabilityper .le,butthatcapability authorizeswriteprivileges for all ten users in the group.


To defeat against such attacks, dynamic analysis may be applied.

dynamic analysis is not e.cient enough to be used as a large-scale detection approach.


As early adoption could change their online-identity market shares, major CSPs moved quickly to gain the marketing and thought-leadership bene.ts by simply being an IdP.

being a RP can impose risks on their business with no direct returns.


The model may not be appropriate for many situations when we do not have any background knowledge about the parties, e.g., P1 and P2 in our case.

the semi-honest model suits our problem domain very well because we assume P1 and P2 are two cloud service providers.


Thus, if we want to de.ne that certain subjects or members of a certain role are allowed to perform two SME tasks in exceptional (emergency) situations, we must explicitly de.ne a corresponding break-glass override via the bbr or bbs mappings (see De.nition 2).

dME constraints de.ne that two dynamically mutual exclusive tasks must never be performed by the same subject in the same process instance.


For all the buffer over.ow attacks whose actual attack packets are publicly available, the above signature can detect them all without any false negatives.

the above signature could also trigger many false positives, especially when the hijack destination word is assumed to appear in the attack packet only once or twice.


Only ReVirt follows the first two principles by enabling the re-creation of all events.

the non-deterministic events that ReVirt records are analyzable only with great difficulty.


Each relying node is equipped with a policyMaker engine which is able to determine the visitor s capability such as access permission locally based on its certificate.

their proposal still relied on centralized public key infrastructure for public-key verification.


We adopt the same DSSS communication framework as illustrated in Figure 1.

the sender and receivers use different strategies to decide what spreading codes to use during broadcast communication.


The time and bandwidth for precomputation and protocol execution are listed separately in Table 3.

bandwidth requirements for garbled circuits is between 37.5 and 41.0 kB, more than twice as much as the 7 to 14 kB required for Erkin s protocol.


Lastly, there are many client applications that automatically store and submit a user s passwords to her SPs [21, 29].

malware on the user s system can often steal passwords from these applications [3].


In a recent blog post, Ben Toews again brought up the issue of password managers that were prone to XSS attacks [28].

the question on how to improve the security of password managers remained unanswered.


Fortunately, as the attack intensity tends to zero, so does the expected pro.t R. We assume that the good nodes report honest opinions about other nodes in the network.

the bad nodes manipulate their opinions with the goal of making their opinion vector similar to that of the good nodes.


3.1.4 Multiple-Faked Identities Profile Similarity (MFIPS) In previous sections, we characterized the friend networks of a faked identity based on assumption that an adversary does not create faked identities that forge friends of the victim.

an intelligent adversary can create multiple faked identities related to a single victim.


Software-based approaches can assign various policies to detect a wide range of attacks including high-level semantic attacks.

they come with a heavy performance slowdown ranging from 4.6X to 37X [22, 18].


The greater the random variation, the better the PUF signature quality (uniqueness, reliability, unpredictability).

manufacturing variations are extremely detrimental to the other parts of the chip since they increase the probability of yield loss.


[2] At this level of speci.city, such an argument is unquestionably sound.

the process of reducing such intuition to a reasonable password expiration policy would ideally be grounded in measurements of what additional steps the policy hoists on an attacker, so as to be certain that these additional steps are an impediment to his continued access.


Theresultingprotocol can compute severalfunctions(including CODIS) on sample T and pattern p, using the number of circuits linear in the number of occurrences of p. Complexityincurredby the underlying keyword searchprotocolislinearin |T|.

common knowledge of some threshold on the number of occurrences needs tobe assumed.


Our pro.les predict that the application itself is not very intrusive.

like many free applications it contains ad libraries (we detected code from .ve) and these ads are responsible for much of the privacy-intrusive behavior.


Hence, the protection requirement of the application determines the granularity of the CNs.

the analysis in Section 4.3 shows that more CNs do not necessarily provide stronger security, but increase the overhead of the self-healing scheme.


The worker can communicate with the current connection Cx1.

it cannot communicate with the previous connection Cx.


XACML v2 employs two versions of dov, one for combining rules and one for combining policies [1, C.1].

the operator dov for policy is based on a single interpretation of Indeterminate and has the following behavior: dov(Indeterminate, Permit) = Deny dov for rules takes into account the e.ect of the rule in which the error occurred in order to make a decision.


Finally, we deployed the policies in the device and executed the malware samples until the attack was performed and the respective policy enforced.

before executing this last step the device was .ashed and a new image installed to remove any side effect caused by the malware.


The security bene.ts of starting from scratch on a closed box special-purpose platform can be signi.cant.

for most applications these bene.ts do not outweigh the advantages of generalpurpose open platforms that run many applications including a huge body of existing code and that take advantage of commodity hardware (CPU, storage, peripherals, etc.)


They are not universally available, are not used by most applications, and can be turned o. without a.ecting most tasks.

microphones are universally available and indispensable on all mobile phones; cameras and GPS receivers are moving in this direction as well.


RESULTS We focus the presentation of our results on the public ISCX dataset due to its reproducibility, as well as space limitations.

the .gures and discussion below also apply to the Columbia dataset, with the primary di.erence being tighter error bounds due to a larger number of samples and a smaller di.erence between aggregate and local supervised content models.


As a result, the Trojan horse executed by a user will carry the user s identity and has all privileges associated with the user.

the reality is that when one user s process executes a program controlled by another user (possibly a trojan planted by an attacker), both the invoker and the controllers of the program content may affect the requests made by the process.


As we can see, in general the 2AP method outperforms NTP.

the 2AP-T method is always signi.cantly better than both the NTP and the 2AP methods.


For service providers like Gmail that are reluctant to host everything over HTTPS, it is still feasible to host relatively unimportant content in unprotected subdomains owing to the nature of domain segmentation.

acquiring valid certificates is no longer a barrier towards adopting SSLock.


Since they are not adjacent, it is not deletion.

start[5] = end[2] + 1, so an insertion of segments 3 and 4 (eighth and ninth characters, to) is detected.


Notice that since the source of saint is not available and there are no published results of the framework s performance overhead, we are unable to compare our results with core saint.

the transformation aspect of our framework would use the same amount of cpu time for saint as it does for apex.


In MU-MIMO with physical security, the data .eld is precoded by ZF-BF and transmitted with arti.cial noise as discussed in Section 2, so it does not leak CSI to eavesdroppers.

preambles such as L-STF, L-LTF, L-SIG, and HT-SIG are transmitted without precoding for backward compatibility, thus enabling all receivers to sense these control .elds.


[14]show empirically that composing mitigators sequentially performs well, which makes sense because mitigated output has more predictable timing.


This may result in ambiguity in analysis, because VM2 is not allowed to access L1 data.

when B of level L2 sends a communication to C of level L2, this should be allowed.


Like a passive attacker it can eavesdrop on the channel between a valid reader and a valid tag.

like an active attacker, AA can install a rouge reader RA that can communicate with a valid tag.


DISCUSSIONS We have not conducted experimental studies on the Image-Dependent Discretization (IDD) scheme [18] due to lack of details to implement the scheme.

it is possible to apply our ideas for attacking Centered Discretization to mount dictionary attacks on this IDD as well.


Finally, we also extended near-optimal evasion to general lp costs; i.e., costs based on lp distances.

we showed that the algorithms for l1 costs can also be extended to near-optimal evasion on lp costs,butaregenerallynot e.cient.in the cases when these algorithms are not e.cient, we show that there is no e.cient query-based algorithm.


Given the value cre and accessing to the TPM for t.sign, the host is able to compute such a proof.

without accessing the TPM for t.sign, the host is not able to do so.


The upper bound for undetectable injections is given by the T-ProT or T-AxT methods, which address larger injections and omission of code sections in favor of injected code.

disguising the side effects of polluting stacks and registers is non-trivial.


As PCR[t+3] and above will still hold the same values after a software update, representing the software s properties, these functions won t be a.ected.

to prevent attackers from bypassing security policies by changing the PBBL or by deleting the NV-Space to rollback software versions, software should also be sealed to all other PCRs except PCR[t+2] which includes the current CL serial number.


is ambiguous at the join-point of the .rst if-else block.

we point out that at the return statement the dynamically quali.ed set of contexts becomes a singleton, that is, the end context is precisely known.


For example, CQUAL has been used to .nd format string vulnerabilities [42].

to use their results, programmers must examine the output and the original source program using an advanced graphical interface and attempt to determine manually whether the reported vulnerability is real or a false positive.


Our notion is also closely related to the notion of protocols for conditional disclosure of secrets [5, 1], where (for the two-party setting), a receiver is able to obtain the sender s secret if a .xed condition C is satis.ed by the receiver s input.

such protocols have been typically considered for speci.c (usually algebraic) conditions C. in our setting, this condition itself is both chosen by the sender and must remain secret from the receiver.


Unattended devices: devices may be left unsecured either because their owners expect that they will remain under their physical control.

if dont, they are open to use by anyone.


On the one hand, this meant that one did not need to worry if the onion routers in a reply onion would be functional at the time the reply onion was actually used.

one had to maintain open circuits to introduction locations at which the hidden server could be contacted.


Definition of Truth Table Actual Positive Negative Predicted Positive a b Negative c d  (2) (3) (4) (5)  It is important to note that most methods used in previous research, report only accuracy value ratings.

a high accuracy rate may not tell the entire story.


Thus we conclude that the covert .ltering process should also resist database attacks for the What s Up captcha.

it appears that the scenario in Sketcha where there are more components, each solved more easily, o.ers better resistance to this form of attack.


SAT WM: Variable Definitions Normally, there is little freedom in redefining the natural set of variables in SAT.

augmented variables allow the imposition of complex relationships among the existing and/or augmented constraints.


However, modern operating systems (such as iOS) enforce the W .X (Writable xor Executable) security model that prevents an adversary from executing injected code.

codereuse attacks such as return-oriented programming [3, 7, 9, 10] bypass W .


We .nd that when only one location is leaked, very few functions have an USS of zero.

as the number of locations leaked increases, the USS decreases.


If S denotes the static part of the attack surface and D denotes the dynamic part, the na¨ive measure would be D .


The presented results show that this is a promising research branch that is getting us to implement e.cient and robust localization solutions.

further research is still needed on the integration of reputation schemes with clustering; solutions not only providing accurate predictions of a primary source s location but also identifying malicious nodes.


The user-name and password combination is the most widely used scheme, because of its simplicity.

this scheme also provides no direct information about the user.


The evolutionary algorithms have been applied to solve some real world problems in the domain of network security.

only little work is done on the application of evolutionary algorithms in detecting DoS attacks on IMS.


There appears to be adilemma: ifwehavemorepeopleonline, theidentityof the existing users will be better shadowed than they are right now.

in this way, we may put more people under risk.


Non-sensitive information is allowed to leave the device to any external location.

if the information is sensitive, our policy enforcement engine will check if a policy exists for the type of data and the external location.


HTTPi shares much of the motivation with our approach when arguing that integrity without con.dentiality is often desired.

hTTPi occupies a somewhat different point in the design space.


This can be compared to digital money,where only certain trusted parties (banks) are allowed to issue digital coins and users have to verify the validity of digital coins.

1A well-known example is the so called Sonny Bono Copyright Term Extension Act ,which extended the term of copyright protection for most works to life plus 75 years.


WPAD is a very convenience way for the management of network administrator.

in the meantime, it may lead to a potential compromise to our LANs.


In the latter case, we identify a series of apps (possibly with the same authorship) which are claimed to be able to spoof the caller s identity or changing the caller s voice (referred to as spoof call malware).

when a user placesacall(e.g.,toadomesticnumber),thecall will .rst pass throughanIRSF number(i.e., as aproxy)before reach  Table 2: Categorization of fraud activities  Revenue Channel Description Pct.


The recovery activities of infected .les and application processes are carefully synchronized to eliminate inconsistency between repaired .le and process states.

sHELF coordinates system-wide damage tracking and quarantine operations to precisely determine and quarantine malicious and infected objects in the system quickly after the intrusion symptoms are detected.


Note that the accuracy of our approach when setting both con.dence and similarity thresholds to 0.2 is 0.634, which is the best accuracy in Figure 1(c).

this accuracy is still worse than that when setting con.dence threshold to 0.7 and similarity threshold to 0.6, which is 0.616 (see the accuracy of EPGP+ in the uniform scenario in Table I).


When we are making reservations, paying bills, and shopping on-line, we expect these web applications to be secure and reliable.

as the availability ofthese serviceshasincreased,therehasbeen acorresponding increase in the number and sophistication of attacks that target them.


As mentioned above, the attacker could try to provide the SID value to the victim through a crafted URL, in case the application accepts session identi.ers in GET parameters.

as current Web applications only very seldom still allow SIDs in URLs [18], a realistic attack scenario would very likely require the adversary to illegitimately set a cookie.


Any studies on pronounceable passwords and particularly lexical blends would have to overcome similar bias, though perhaps less so than, e.g., graphical passwords.

while the bias toward the familiar may be small due to the similarity between pronouceable and traditional passwords, the same similarity also complicates the analysis by introducing ambiguity as to the actual extent of any bias.


However, in CDDHT, even with the full connectivity knowledge, the best target is just to attack certain SFC.


Function of filtering is one of the solutions which are avoided through those troubles.


This approach is favored because recognition is a more effective manner of retrieval than recall, exhibiting greater accuracy and longevity of material.

schemes such as these combine both the use of graphical images and the use of recognition as a retrieval mechanism.


Most of the current existing solutions rely on the watchdog technique to ensure the correct forwarding of packets by the neighboring nodes.

this technique suffers from certain weakness mentioned in section 2 and analyzed in section 3, particularly when power control is applied.


This is an issue as a receiver may not easily identify valid fragments as described in the paper.

modifying perfect hash functions with a small range such that they map forged fragments to some invalid hash value does not help either, as in this case a single hash function can no longer be perfect for multiple inputs a simple combinatorial argument then yields that the hash function has a minimum representation size  l of log22 n= nl - n log2 n bits if the order of the fragments is ignored (where l denotes the output bit length of a cryptographic hash function and n is the number of fragments in the bundle), or exactly nl bits otherwise, which is precisely the amount of space required for the hash list approach.


There has been a great deal of research devoted to new PUF designs for better performance and reliability [15, 2, 4].

these works focus on designs at a purely architectural level.


Vanity, Cracks and Malware Insights into the Anti-Copy Protection Ecosystem Markus Kammerstetter, Christian Platzer and Gilbert Wondracek Vienna University of Technology Vienna, Austria {mk,cplatzer,gilbert}@iseclab.org  ABSTRACT Today, a large amount of software products include mechanisms to counter software piracy.

most protection mechanisms can be easily circumvented by applying software patches (cracks) or license key generators (keygens) with seemingly no .nancial incentives.


increases, which is the x-axis in Figure 3(a) to (d).

it gives us an interesting insight that as the order increases, very few states have higher probability of occurrence and rest of the states probabilities drop to a negligible value.


(For more on fuzzy time, see Gray [7, 8].)

it is not clear that this approach translates to current hardware architectures such as the x86 and current virtual machine monitors such as Xen.


Thus, a new mobile identi.cation recognition system is expecting to be developed to solve those security issues in mobile commerce applications.

the embedded mobile cameras are capable of acquiring quali.ed .ngerprint images for identity authentication.


Binary search trees take longer time for the insert operation compared to a normal sequential list (O(log n) as opposed to O(1)).

our insert operation is not as critical as the search since the insert is less frequent than the search.


In this case, the blockerror distribution can be computed by a recursive algorithm described in [3 5].

the above models are only applicable to delayinsensitive media applications.


It remains an open question whether a combination of motion sensors with the ambient-light sensor leads to better performances than reported so far.

the intention of this work was to provide a .rst feasibility study.


The only exception is mutual authentication through establishing SSL or TLS channels where the browser holds a client certi.cate.

this is not considered truly zero-footprint, as users have to install a client certi.cate in their browser.


The Ciphertext-Policy Attribute-based Encryption (CP-ABE) [1, 7] is regarded as one of the most suitable technologies for data access control in cloud storage systems, because it gives the data owner more direct control on access policies and the policy checking occurs inside the cryptography".

due to the attribute revocation problem, it is very costly to apply the CP-ABE approach to control the data access in cloud storage systems.


A security protocol should enforce the data exchange between honest participants, while the dishonest ones should be denied any bene.t of it.

any .aws in the design of a security protocol can be exploited by an attacker.


One can also use PGP in an instant-messaging code with the appropriate glue logic.

[14] these approaches o.er very di.erent security and privacy properties.


According to RFC 6434, IPsec should be supported by all IPv6 nodes [8].

iPsec is not appropriate for securing IPv6 Neighbor Discovery Protocol (NDP) [16], [17].


The third rule decrements the counter if the function returns ordinary to its caller.

the probes for the second rule will .re before rule three is applied if the counter value is set to null, which means that DTrace has not registered an entry to this function although a return from this function is issued.


We propose two solutions, one that works for property-based attestation, and one that works for both attestation and sealing.

our second solution requires TPM features that are only part of version 1.2 of the speci.cation, while the .rst solution for property-based attestation can even work with older TPM hardware.


This technique is orthogonal to the one presented to far: it can be applied on top of it or on the original DFA before the default transition computation is performed.

the basic idea is the following: in a DFA recognizing regular expressions over an alphabet S each state has potentially |S| outgoing transitions, one for each symbol in S. S can be partitioned into classes of symbols C1,...,Ck which are indistinguishable for the purposes of the DFA operation.


NEURAL NETWORK INTO INTRUSION DETECTION The ability of soft computing techniques for dealing with uncertain and partially true data makes them attractive to be applied in intrusion detection.

artificial Neural Networks (ANNs) are the most commonly used soft computing technique in IDSs [4,9,10].


Examples are in Inference (4) in Figure 4 and in inference rules that involve the negative rights.


For the higher values of attack aggressivenesses, c3, c4,and c5 become negative, indicating further di.erences between the monitored patterns at the corresponding MSs.

c6, c7,and c8 have high correlation values and remain more or less the same with varying attack aggressiveness.


Focusing on detecting attacks against individual clients is a motivation for this paper.

we address detecting attacks on the multiple communication vectors of mobile devices instead of just 802.11 WiFi.


In particular, many traditional businesses depend on outside suppliers due to the lack of internal skills for effective Internet marketing.

outsourcing business processes implies that an enterprise has to disclose its customers' PII to the outside.


Exactly how much of each type of data one needs to compute in the of.ine phase is of course unknown until the exact function one is computing is known.

one can make a heuristic over estimate of this number.


INSTALL_PACKAGES permission, because this is a privilege permission only reserved for system applications.

pre-installed applications are di.erent.


Finally, we note that there are attacks against provisioning that might allow an adversary to provision his TIM to the user s SP account.

the window of opportunity for these attacks is limited.


Also note that the fbconnect problem here is present on both Android and iOS.

given that iOS malware is rare, the risk it poses is mainly to Android (see our adversary model).


Each operating system and its applications run in a single VM that is typically isolated from the other VMs, except through network communications or storage.

mandatory access control (MAC) systems for VM systems have emerged [26, 22, 23].


Our hope was that this would spread the initial point to a larger set of three or four points, thus potentially increasing the entropy of chosen patterns.

reducing the number of points has the potential to reduce both length and complexity of patterns, thus decreasing entropy.


The purpose of this analysis is to understand the accuracy behavior of our scheme.

we must emphasize that the comparison is slightly unfair as no other classi.er that has been compared has the ability to do in-execution detection.


For example, when 6For many common elliptic curves, this is the G1 base group.

in some curves the groups G1 and G2 have similar operation costs; this may give us some .exibility in modifying the equation.


This minimizes communication overhead while achieving the same level of security and ef.ciency as in PSW.

an auditor could still cheat, e.g., by using wrong parameters or by biasing the challenge sampling process according to some strategy.


A small branch, say at a university campus would have a limited number of transaction types and all the staff would be directly involved in performing the basic banking services.

the manager of a large branch in a commercial area may be managing a large variety of transactions through a hierarchy of specialist managers.


Indeed, this is a particular example of the use of the probabilistic method, a technique which is now ubiquitous in asymptotic geometric analysis.

it is usually the case that objects constructed in such a manner are very hard to come by explicitly.


These studies concluded that the memory requirements of holding route information, the necessary certi.cates, and related cryptographic data are the major hurdle.

our previous studies in [35, 46] examined S-BGP performance using simulation.


In particular, this gives a broadcast encryption system secure against adaptive adversaries.

instead of directly building a trace and revoke system we build a simpler primitive we call Augmented Broadcast Encryption or ABE for short.


Moreover, as VMs can be migrated among di.erent nodes, and these migrations are ought to be transparent to users, di.culties are intensi.ed for separated attestation scheme to accurately determine the trust states of the exact dependency for a user s cloud application.

as appropriate repeatedly attestation timing can only be decided according to the communication patterns of particular VMs, it is hence di.cult for the combined attestation scheme to determine the strategies to satisfy attestation needs of every application in the cloud.


However, for production workload servers with large disk and raw memory, this stopping-the-world checkpointing will cause intolerable service downtime to the servers.

we observed that during 2:00 am to 5:00 am, the amount of service requests are much more degraded than that during daytime for Amazon-style servers.


It realizesPrivateSet Intersection[32], where setscorrespondto contactlists.

computation overhead appears to be still too high, in practice, to scale uptofully sequencedgenomes, since executing CommonContacts onlists with256 entries takes about10 minutes[39].


On the one hand, the service provider (a company or an hospital) may not be willing to provide the end user directly with its proprietary protocols because of fear of disclosing valuable intellectual property to third parties or compromising the basis for its service.

patients or users of the service might not be willing to disclose their personal signal information to a third party (not necessarily a hospital or doctor) for fears of losing control of their data (e.g., a user might be concerned that due to certain medical condition his insurance premium will increase or that he will be discriminated during a job application).


By automatically resolving every con.ict at the moment of composition, it may be that a poor choice of resolution is made.

it may be that a uniform method is desired for resolving con.icts.


We treated posts as documents and their policies as labels, and used LLDA to predict the policies for a test set of posts that did not have policies attached.

we found the performance of LLDA to be poor in our setting.


explanations, and individual recommendations come with a justi.cation [3].

in the user-controlled policy learning approach presented in this paper, the user and the recommendation system operate hand-in-hand, improving on a common policy model, with the user free to accept, modify, or reject any recommendations before they are applied.


If n is larger than 2m+1 , most users must share their codeword with another user, thus even if a single user distributes his copy, any algorithm that accuses him will accuse another user too.

from Theorems 1 and 2 it clearly follows that Corollary 3.


More generally, given an RCP instance that asks whether UP satis.es rp(P, s, d, t), if s + d > tb(UP, P ), then the answer is no .

when d = 2 and s + d = tb(UP, P ), we do not immediately know whether UP satis.es rp(P, s, d, t) or not.


To date such malwaremalware synergies have been mostly accidental, although there are intentional examples as well, such as the CTX virus strategy of piggybacking on the Cholera worm.

it is only a matter of time before malware authors realize the potential of this technique.


The ability to monitor participants changes and respond to all threat situations which occurred, suggests that Impromptu was successful as a means of visualizing system activity.

there was a sense that visualizing only the immediate state of the system was inadequate to address all of the participants needs.


For example, many such schemes require JavaScript to be enabled.

some users might prefer to disable JavaScript in their browsers.


If the kernel is non-preemptive, this transient e.ect guarantees the ATRA-a.ected process to access the relocated kernel object.

if the kernel is preemptive, on a rare occasion, the transient e.ect might vanish before the target kernel object is accessed.


h),MSP|=MP4 h. Otherwise, accordingto the structure of q, this rule would not be used in the proof.

as h .. activehead(ePaPB), ePaPB.|=MP4 h;a contradiction.


We also analyze the outputs of our digital PUF using the security principles of confusion and di.usion, as presented by Shannon [2], through demonstration of the avalanche criterion.

despite the theoretically sound and mathematically proven security properties of many digital cryptographic systems, there exist many potential side-channels which can e.ectively bypass these mathematical constructs altogether by reading internal memory or inferring internal procedures through power analysis and memory attacks.


To acquire Md, we can run our SVM and take its memory snapshot before (Mbef ore ) and after (Maf ter ) executing a con.guration utility, and then we can get Md = Maf ter -Mbef ore .

such an approach only works if and only if Md is located inDglobal If Md includes any Dheap data, it will fail kernel .


We will discuss the reasons for doing this below.

an application running on its own in a VM cannot interact with other processes normally found in a commodity OS, making it less useful.


This e.ort did not evolve into a standard.

the work was considered to be of su.ciently high quality that a draft was made publicly available [27].


That is, they demand a high number of interactions before a change of behavior is reflected in the computed trust value.

the trust computation metrics employed by the existing systems do not provide adequate reaction to quick changes in peers behavior [16].


Therefore, it corresponds to either an authorization policy assertion or a planning assertion.

a privacy policy for a resource, described by a privacy policy assertion, de.nes for which purposes the resource will be used, by whom it will be used, and for how long it will be retained.


Type D heuristics expect the artifacts/tokens that are prevalent in real devices.

device manufacturers inevitably customize devices and change artifacts, which makes it harder to .nd the artifacts that exist in every real device.


With such a large percentage of .onion requests originating in the United States, it is not surprising to observe the major Internet Service Providers (ISP) in Table 4 (AS7922 is Comcast and AS7018 is AT&T)2 .

it is interesting to observe that nearly 8% of all .onion traf.c originates from AS15169 (Google).


When we decided to create a complex competition, we knew that not every team would have the skills, experience, and luck to exploit a service and understand the Petri net mission model.

we included 33 challenges in the competition of varying levels of di.culty and needing various skills to solve.


This server is a trusted online entity, and in that respect our model bears similarites to closed credential platforms in which credential management is controlled by a central authority.

in our model the user is allowed to choose this trusted entity freely with the cost of importing a new trust root during device initialization.


If he submits this new document to the time-stamping service, later veri.cation by the acquirer will fail because the time-stamp of the document is past the certi.cate end date.

if one assumes that the attacker has the capability to brute-force the supplier certi.cate private key, one can equally well assume that the attacker can also brute force the private key of equal strength of the time-stamping authority, investing the same order of magnitude of e.ort.


The common mode can be less e.cient than the attach mode, as individual mixes must route their messages to the head of the cascade for transmission.

in the common mode, an adversary must convince a mix that a message the adversary is asking the mix s help to trace is not the mix s own message, because the mix cannot recognize its own messages in a re-encryption mix-net [1].


For instance, in the case of a sandboxed process, if the process is bound by the kernel to execute in split-hardened context, the attacker needs to .rst compromise another process that executes in split-base mode.

in doing so, the attacker needs to escape the sandbox .rst, which is typically their initial motivation for using a kernel exploit [15].


For example, an unscrupulous ad hoster could display many hundreds of ads on a single webpage, driving up revenue.

the bene.t to the advertiser would be very limited, as the ad would essentially be lost on the page that chances of the ad being noticed by a potential customer are low.


If network administrators apply these suggestions, that would make the classic network address scans less feasible.

our IPv6 address usage survey shows that some network administrators use customized IID allocation mechanisms to satisfy different requirements, so it is possible to launch a network reconnaissance attack in IPv6 networks by using appropriate heuristics.


As described above, cellular networks indeed perform controlplane authentication when assigning an IP address.

for packet delivery on the data plane, enforcement of the assigned, authentic IP address may be missing.