Dual channel-based network traffic authentication

In a local network or the Internet in general, data that is transmitted between two computers (also known as network traffic or simply, traffic) in that network is usually classified as being of a malicious or of a benign nature by a traffic authentication system employing databases of previously observed malicious or benign traffic signatures, i.e., blacklists or whitelists, respectively. These lists typically consist of either the destinations (i.e., IP addresses or domain names) to which traffic is being sent or the statistical properties of the traffic, e.g., packet size, rate of connection establishment, etc. The drawback with the list-based approach is its inability to offer a fully comprehensive solution since the population of the list is likely to go on indefinitely. This implies that at any given time, there is a likelihood of some traffic signatures not being present in the list, leading to false classification of traffic. From a security standpoint, whitelists are a safer bet than blacklists since their underlying philosophy is to block anything that is unknown hence in the worst case, are likely to result in high false rejects with no false accepts. On the other hand, blacklists block only what is known and therefore are likely to result in high false accepts since unknown malicious traffic will be accepted, e.g., in the case of zero-day attacks (i.e., new attacks whose signatures have not yet been analyzed by the security community). Despite this knowledge, the most commonly used traffic authentication solutions, e.g., antivirus or antimalware solutions, have predominantly employed blacklists rather than whitelists in their solutions. This can perhaps be attributed to the fact that the population of a blacklist typically requires less user involvement than that of a whitelist. For instance, malicious traffic signatures (i.e., behavior or destinations) are usually the same across a population of users; hence, by observing malicious activity from a few users, a global blacklist that is applicable to all users can be created. Whitelist generation, on the other hand, tends to be more user-specific as what may be considered acceptable or benign traffic to one user may not be considered the same to a different user. As a result, users are likely to find whitelist-based solutions that require their participation to be both cumbersome and inconveniencing. This dissertation offers a whitelist-based traffic authentication solution that reduces the active participation of users in whitelist population. By relying on activity that users regularly engage in while interacting with their computers (i.e., typing), we are able to identify legitimate destinations to which users direct their traffic and use these to populate the whitelist, without requiring the users to deviate from their normal behavior. Our solution requires users to type the destinations of their outgoing traffic requests only once, after which any subsequent requests to that destination are authenticated without the need for them to be typed again. Empirical results from testing our solution in a real time traffic analysis scenario showed that relatively low false reject rates for legitimate traffic with no false accepts for illegitimate traffic are achievable. Additionally, an investigation into the level of inconvenience that the typing requirement imposes on the users revealed that, since users are likely to engage in this (typing) activity during the course of utilizing their computer\u27s resources, this requirement did not pose a significant deterrent to them from using the system

Quantum Lightning Never Strikes the Same State Twice

Public key quantum money can be seen as a version of the quantum no-cloning theorem that holds even when the quantum states can be verified by the adversary. In this work, investigate quantum lightning, a formalization of "collision-free quantum money" defined by Lutomirski et al. [ICS'10], where no-cloning holds even when the adversary herself generates the quantum state to be cloned. We then study quantum money and quantum lightning, showing the following results: - We demonstrate the usefulness of quantum lightning by showing several potential applications, such as generating random strings with a proof of entropy, to completely decentralized cryptocurrency without a block-chain, where transactions is instant and local. - We give win-win results for quantum money/lightning, showing that either signatures/hash functions/commitment schemes meet very strong recently proposed notions of security, or they yield quantum money or lightning. - We construct quantum lightning under the assumed multi-collision resistance of random degree-2 systems of polynomials. - We show that instantiating the quantum money scheme of Aaronson and Christiano [STOC'12] with indistinguishability obfuscation that is secure against quantum computers yields a secure quantum money schem

Noninteractive two-channel message authentication based on hybrid-collision resistant hash functions.

We consider the problem of non-interactive message authentication using two channels: an insecure broadband channel and an authenticated narrow-band channel. This problem has been considered in the context of ad hoc networks, where it is assumed that there is neither a secret key shared among the two parties, nor a public-key infrastructure in place. We present a formal model for protocols of this type, along with a new protocol which is as efficient as the best previous protocols. The security of our protocol is based on a new property of hash functions that we introduce, which we name ``hybrid-collision resistance\u27\u27

Message Authentication and Recognition Protocols Using Two-Channel Cryptography

We propose a formal model for non-interactive message authentication protocols (NIMAPs) using two channels and analyze all the attacks that can occur in this model. Further, we introduce the notion of hybrid-collision resistant (HCR) hash functions. This leads to a new proposal for a NIMAP based on HCR hash functions. This protocol is as efficient as the best previous NIMAP while having a very simple structure and not requiring any long strings to be authenticated ahead of time. We investigate interactive message authentication protocols (IMAPs) and propose a new IMAP, based on the existence of interactive-collision resistant (ICR) hash functions, a new notion of hash function security. The efficient and easy-to-use structure of our IMAP makes it very practical in real world ad hoc network scenarios. We also look at message recognition protocols (MRPs) and prove that there is a one-to-one correspondence between non-interactive MRPs and digital signature schemes with message recovery. Further, we look at an existing recognition protocol and point out its inability to recover in case of a specific adversarial disruption. We improve this protocol by suggesting a variant which is equipped with a resynchronization process. Moreover, another variant of the protocol is proposed which self-recovers in case of an intrusion. Finally, we propose a new design for message recognition in ad hoc networks which does not make use of hash chains. This new design uses random passwords that are being refreshed in each session, as opposed to precomputed elements of a hash chain

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Noninteractive Manual Channel Message Authentication Based On eTCR Hash Functions

We present a new non-interactive message authentication protocol in manual channel model (NIMAP, for short) using the weakest assumption on the manual channel (i.e. assuming the strongest adversary). Our protocol uses enhanced target collision resistant (eTCR) hash family and is provably secure in the standard model. We compare our protocol with protocols with similar properties and show that the new NIMAP has the same security level as the best previously known NIMAP whilst it is more practical. In particular, to authenticate a message such as a 1024-bit public key, we require an eTCR hash family that can be constructed from any off-the-shelf Merkle-Damgård hash function using randomized hashing mode. The underlying compression function must be {\em evaluated second preimage resistant} (eSPR), which is a strictly weaker security property than collision resistance. We also revisit some closely related security notions for hash functions and study their relationships to help understanding our protocol

CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS

In large-scale distributed systems, where adversarial attacks can have widespread impact, authentication provides protection from threats involving impersonation of entities and tampering of data. Practical solutions to authentication problems in distributed systems must meet specific constraints of the target system, and provide a reasonable balance between security and cost. The goal of this dissertation is to address the problem of building practical and efficient authentication mechanisms to secure distributed applications. This dissertation presents techniques to construct efficient digital signature schemes using trapdoor hash functions for various distributed applications. Trapdoor hash functions are collision-resistant hash functions associated with a secret trapdoor key that allows the key-holder to find collisions between hashes of different messages. The main contributions of this dissertation are as follows: 1. A common problem with conventional trapdoor hash functions is that revealing a collision producing message pair allows an entity to compute additional collisions without knowledge of the trapdoor key. To overcome this problem, we design an efficient trapdoor hash function that prevents all entities except the trapdoor key-holder from computing collisions regardless of whether collision producing message pairs are revealed by the key-holder. 2. We design a technique to construct efficient proxy signatures using trapdoor hash functions to authenticate and authorize agents acting on behalf of users in agent-based computing systems. Our technique provides agent authentication, assurance of agreement between delegator and agent, security without relying on secure communication channels and control over an agent’s capabilities. 3. We develop a trapdoor hash-based signature amortization technique for authenticating real-time, delay-sensitive streams. Our technique provides independent verifiability of blocks comprising a stream, minimizes sender-side and receiver-side delays, minimizes communication overhead, and avoids transmission of redundant information. 4. We demonstrate the practical efficacy of our trapdoor hash-based techniques for signature amortization and proxy signature construction by presenting discrete log-based instantiations of the generic techniques that are efficient to compute, and produce short signatures. Our detailed performance analyses demonstrate that the proposed schemes outperform existing schemes in computation cost and signature size. We also present proofs for security of the proposed discrete-log based instantiations against forgery attacks under the discrete-log assumption

Practical Unconditionally Secure Two-channel Message Authentication

We investigate unconditional security for message authentication protocols that are designed using two-channel cryptography. We look at both noninteractive message authentication protocols (NIMAPs) and interactive message authentication protocols (IMAPs). We provide a new proof of nonexistence of nontrivial unconditionally secure NIMAPs. This proof consists of a combinatorial counting argument and is much shorter than the previous proof by Wang et al., which was based on probability distribution arguments. Further, we propose a generalization of an unconditionally secure 3-round IMAP due to Naor, Segev and Smith. With a careful choice of parameters, our scheme improves that of Naor et al. Our scheme is very close to optimal for most parameter situations of practical interest.