This paper establishes a fundamental theory of secure clock synchronization. Accurate clock synchronization is the backbone of systems managing power distribution, financial transactions, telecommunication operations, database services, etc. Some clock synchronization (time transfer) systems, such as the global navigation satellite systems, are based on one-way communication from a master to a slave clock. Others, such as the network transport protocol, and the IEEE 1588 precision time protocol (PTP), involve two-way communication between the master and slave. This paper shows that all one-way time transfer protocols are vulnerable to replay attacks that can potentially compromise timing information. A set of conditions for secure two-way clock synchronization is proposed and proved to be necessary and sufficient. It is shown that IEEE 1588 PTP, although a two-way synchronization protocol, is not compliant with these conditions, and is therefore insecure. Requirements for secure IEEE 1588 PTP are proposed, and a second example protocol is offered to illustrate the range of compliant systems.
In @cite_1 , it is remarked that the clock offset computed between multiple master clocks over a symmetric channel must be zero, and thus, if multiple master clocks are available, they can detect any malicious delay introduced by an adversary. However, this defense does not consider the possibility that the adversary may only delay the packets sent to the slave nodes.
@cite_1
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Most commercial multi-core processors incorporate hardware coherence protocols to support efficient data transfers and updates between their constituent cores. While hardware coherence protocols provide immense benefits for application performance by removing the burden of software-based coherence, we note that understanding the security vulnerabilities posed by such oft-used, widely-adopted processor features is critical for secure processor designs in the future. In this paper, we demonstrate a new vulnerability exposed by cache coherence protocol states. We present novel insights into how adversaries could cleverly manipulate the coherence states on shared cache blocks, and construct covert timing channels to illegitimately communicate secrets to the spy. We demonstrate 6 different practical scenarios for covert timing channel construction. In contrast to prior works, we assume a broader adversary model where the trojan and spy can either exploit explicitly shared read-only physical pages (e.g., shared library code), or use memory deduplication feature to implicitly force create shared physical pages. We demonstrate how adversaries can manipulate combinations of coherence states and data placement in different caches to construct timing channels. We also explore how adversaries could exploit multiple caches and their associated coherence states to improve transmission bandwidth with symbols encoding multiple bits. Our experimental results on commercial systems show that the peak transmission bandwidths of these covert timing channels can vary between 700 to 1100 Kbits sec. To the best of our knowledge, our study is the first to highlight the vulnerability of hardware cache coherence protocols to timing channels that can help computer architects to craft effective defenses against exploits on such critical processor features. In the wireless sensor networks (WSNs), sensor nodes may be deployed in the hostile areas. The eavesdropper can intercept the messages in the public channel and the communication between the nodes is easily monitored. Furthermore, any malicious intermediate node can act as a legal receiver to alter the passing messages. Hence, message protection and sensor node identification become important issues in WSN. In this paper, we propose a novel scheme providing unconditional secure communication based on the quantum characteristics, including no-cloning and teleportation. We present a random EPR-pair allocation scheme that is designed to overcome the vulnerability caused by possible compromised nodes. EPR pairs are pre-assigned to sensor nodes randomly and the entangled qubits are used by the nodes with the quantum teleportation scheme to form a secure link. We also show a scheme on how to resist the man-in-the-middle attack. In the framework, the qubits are allocated to each node before deployment and the adversary is unable to create the duplicated nodes. Even if the malicious nodes are added to the network to falsify the messages transmitting in the public channel, the legal nodes can easily detect the fake nodes that have no entangled qubits and verify the counterfeit messages. In addition, we prove that one node sharing EPR pairs with a certain amount of neighbor nodes can teleport information to any node in the sensor network if there are sufficient EPR pairs in the qubits pool. The proposal shows that the distributed quantum wireless sensor network gains better security than classical wireless sensor network and centralized quantum wireless network. We consider the problem of computing a maximal independent set (MIS) in an extremely harsh broadcast model that relies only on carrier sensing. The model consists of an anonymous broadcast network in which nodes have no knowledge about the topology of the network or even an upper bound on its size. Furthermore, it is assumed that an adversary chooses at which time slot each node wakes up. At each time slot a node can either beep, that is, emit a signal, or be silent. At a particular time slot, beeping nodes receive no feedback, while silent nodes can only differentiate between none of its neighbors beeping, or at least one of its neighbors beeping. We start by proving a lower bound that shows that in this model, it is not possible to locally converge to an MIS in sub-polynomial time. We then study four different relaxations of the model which allow us to circumvent the lower bound and find an MIS in polylogarithmic time. First, we show that if a polynomial upper bound on the network size is known, it is possible to find an MIS in ( O ( ^3 n) ) time. Second, if we assume sleeping nodes are awoken by neighboring beeps, then we can also find an MIS in ( O ( ^3 n) ) time. Third, if in addition to this wakeup assumption we allow sender-side collision detection, that is, beeping nodes can distinguish whether at least one neighboring node is beeping concurrently or not, we can find an MIS in ( O ( ^2 n) ) time. Finally, if instead we endow nodes with synchronous clocks, it is also possible to find an MIS in ( O ( ^2 n) ) time. We present a novel approach to proving the absence of timing channels. The idea is to partition the programâ s execution traces in such a way that each partition component is checked for timing attack resilience by a time complexity analysis and that per-component resilience implies the resilience of the whole program. We construct a partition by splitting the program traces at secret-independent branches. This ensures that any pair of traces with the same public input has a component containing both traces. Crucially, the per-component checks can be normal safety properties expressed in terms of a single execution. Our approach is thus in contrast to prior approaches, such as self-composition, that aim to reason about multiple (kâ � 2) executions at once. We formalize the above as an approach called quotient partitioning, generalized to any k-safety property, and prove it to be sound. A key feature of our approach is a demand-driven partitioning strategy that uses a regex-like notion called trails to identify sets of execution traces, particularly those influenced by tainted (or secret) data. We have applied our technique in a prototype implementation tool called Blazer, based on WALA, PPL, and the brics automaton library. We have proved timing-channel freedom of (or synthesized an attack specification for) 24 programs written in Java bytecode, including 6 classic examples from the literature and 6 examples extracted from the DARPA STAC challenge problems.