In this paper, we present a new family of fountain codes which overcome adversarial errors. That is, we consider the possibility that some portion of the arriving packets of a rateless erasure code are corrupted in an undetectable fashion. In practice, the corrupted packets may be attributed to a portion of the communication paths which are controlled by an adversary or to a portion of the sources that are malicious. The presented codes resemble and extend LT and Raptor codes. Yet, their benefits over existing coding schemes are manifold. First, to overcome the corrupted packets, our codes use information theoretic techniques, rather than cryptographic primitives. Thus, no secret channel between the senders and the receivers is required. Second, the encoders in the suggested scheme are oblivious to the strength of the adversary, yet perform as if its strength was known in advance. Third, the sparse structure of the codes facilitates efficient decoding. Finally, the codes easily fit a decentralized scenario with several sources, when no communication between the sources is allowed. We present both exhaustive as well as efficient decoding rules. Beyond the obvious use as a rateless codes, our codes have important applications in distributed computing.
In @cite_3 , a slightly different technique for packet verification in rateless codes is used. Therein, a Merkle-tree @cite_4 based signature structure is suggested. However, the solution proposed is, still, only valid against computationally bounded adversaries and relies on the existence of homomorphic, collision-resistant hash functions. Furthermore, as the size of a Merkle-tree is linear in the size of the original message, the authors propose a process of repeated hashing to reduce the size of the tree. Such recursive application of a hashing function is more likely to be susceptible to attack. An efficient scheme for signature generation of rateless codes appears in @cite_7 , where the authors use the computational hardness of the discreet log to provide a pki which enables the sender to efficiently sign each packet transmitted. The scheme is based on looking at the data being sent as spanning a specific vector space, and looking at packets as valid as long as they belong to the same vector space. The verification part uses standard cryptographic devices to facilitate the check.
@cite_4 @cite_7 @cite_3
1999949961 2524874630 1862268400 2107511818
Smart metering application has received a lot of attention from the research community lately. Usually, LLN based network runs on RPL protocol which constructs a DAG structure for its normal operation. In this paper, we devise a wormhole attack scenario in such a network. Furthermore, we propose a Merkle tree based authentication protocol which runs on the notion of constructing a tree of hashed security information. We evaluated the approach by formulating the wormhole problem as graph theoretic problem and have shown the effectiveness of the proposed Merkle tree based approach for authenticating communications. Furthermore, we perform simulations in NS 2 to observe the network performance by adopting Merkle tree based to prevent from disrupting the links and observed boost in throughput, reduction in jitter and end to end delay. In the end, we have taken the step towards optimizing the performance of the algorithm by proposing an effective tree traversal algorithm which works on the notion of electing nodes as root in a large scale network from where a Merkle tree will be originated this will assist in managing the authentication in a huge sized network broken down into many trees avoiding wormhole attacks in the network. Given the scalability of the advanced metering infrastructure (AMI) networks, maintenance and access of certificate revocation lists (CRLs) pose new challenges. It is inefficient to create one large CRL for all the smart meters (SMs) or create a customized CRL for each SM since too many CRLs will be required. In order to tackle the scalability of the AMI network, we divide the network into clusters of SMs, but there is a tradeoff between the overhead at the certificate authority (CA) and the overhead at the clusters. We use Bloom filters to reduce the size of the CRLs in order to alleviate this tradeoff by increasing the clusters’ size with acceptable overhead. However, since Bloom filters suffer from false positives, there is a need to handle this problem so that SMs will not discard important messages due to falsely identifying the certificate of a sender as invalid. To this end, we propose two certificate revocation schemes that can identify and nullify the false positives. While the first scheme requires contacting the gateway to resolve them, the second scheme requires the CA additionally distribute the list of certificates that trigger false positives. Using mathematical models, we have demonstrated that the probability of contacting the gateway in the first scheme and the overhead of the second scheme can be very low by properly designing the Bloom filters. In order to assess the scalability and validate the mathematical formulas, we have implemented the proposed schemes using Visual C. The results indicate that our schemes are much more scalable than the conventional CRL and the mathematical and simulation results are almost identical. Moreover, we simulated the distribution of the CRLs in a wireless mesh-based AMI network using ns-3 network simulator and assessed its distribution overhead. In an effort to provide security and data integrity, hashing algorithms have been designed to consume an input of any length to produce a fixed length output. KECCAK was selected by NIST to become the next Secure Hashing Algorithm (SHA-3) after nearly five years of competition. In addition to providing a sequential operating mode, there is also a tree mode that allows large input messages to be hashed in parallel. This work focuses on the exploration and analysis of the KECCAK tree hashing mode on a GPU platform. Based on the implementation, there are core features of the GPU that could be used to accelerate the time it takes to complete a hash due to the massively parallel architecture of the device. In addition to analyzing the speed of the algorithm, the underlying hardware is profiled to identify the bottlenecks that limited the hash speed. The results of this work show that tree hashing can hash data at rates of up to 3 GB s for the fixed size tree mode. On a 3.40 GHz CPU, this is the equivalent of 1.03 cycles per byte, more than six times faster than a sequential implementation for a very large input. For the variable size tree mode, the throughput was 500 MB s. Based on the performance analysis, modification of the input rate of the KECCAK sponge resulted in a negligible change to the overall speed. As a result of the hardware profiling, the register and L1 cache usage in the GPU was a major bottleneck to the overall throughput. The emerging use of the Internet for remote storage and backup has led to the problem of verifying that storage sites in a distributed system indeed store the data; this must often be done in the absence of knowledge of what the data should be. We use m n erasure-correcting coding to safeguard the stored data and use algebraic signatures hash functions with algebraic properties for verification. Our scheme primarily utilizes one such algebraic property: taking a signature of parity gives the same result as taking the parity of the signatures. To make our scheme collusionresistant, we blind data and parity by XORing them with a pseudo-random stream. Our scheme has three advantages over existing techniques. First, it uses only small messages for verification, an attractive property in a P2P setting where the storing peers often only have a small upstream pipe. Second, it allows verification of challenges across random data without the need for the challenger to compare against the original data. Third, it is highly resistant to coordinated attempts to undetectably modify data. These signature techniques are very fast, running at tens to hundreds of megabytes per second. Because of these properties, the use of algebraic signatures will permit the construction of large-scale distributed storage systems in which large amounts of storage can be verified with minimal network bandwidth.