We present, implement, and analyze a new scalable centralized algorithm, called OFT, for establishing shared cryptographic keys in large, dynamically changing groups. Our algorithm is based on a novel application of one-way function trees. In comparison with the top-down logical key hierarchy (LKH) method of Wallner et al., our bottom-up algorithm approximately halves the number of bits that need to be broadcast to members in order to rekey after a member is added or evicted. The number of keys stored by group members, the number of keys broadcast to the group when new members are added or evicted, and the computational efforts of group members, are logarithmic in the number of group members. Among the hierarchical methods, OFT is the first to achieve an approximate halving in broadcast length, an idea on which subsequent algorithms have built. Our algorithm provides complete forward and backward security: Newly admitted group members cannot read previous messages, and evicted members cannot read future messages, even with collusion by arbitrarily many evicted members. In addition, and unlike LKH, our algorithm has the option of being member contributory in that members can be allowed to contribute entropy to the group key. Running on a Pentium II, our prototype has handled groups with up to 10 million members. This algorithm offers a new scalable method for establishing group session keys for secure large-group applications such as broadcast encryption, electronic conferences, multicast sessions, and military command and control.

/pdf/key-establishment-in-large-dynamic-groups-using-one-way-un5khjof28.pdf

Key establishment in large dynamic groups using one-way function trees

A Protocol Test Generation Procedure.

The Internet of Things (IoT) represents a great opportunity to connect people, information, and things, which will in turn cause a paradigm shift in the way we work, interact, and think. IoT devices are usually small, low cost, and have limited resources, which makes them vulnerable to physical, side-channel, and cloning attacks. Therefore, any protocol designed for IoT systems should not only be secure but also efficient in terms of usage of chip area, energy, storage, and processing. To address this issue, we present light-weight mutual authentication protocols for IoT systems based on physical unclonable functions. Protocols for two scenarios are presented, one when an IoT device and server wish to communicate and the other when two IoT devices want to establish a session. A security and performance analysis of the protocols shows that they are not only robust against different types of attacks, but are also very efficient in terms of computation, memory, energy, and communication overhead. The proposed protocols are suitable for real time applications and are an attractive choice for implementing mutual authentication in IoT systems.

Mutual Authentication in IoT Systems Using Physical Unclonable Functions

We investigate protocols for authenticated exchange of messages between two parties in a communication network. Secure authenticated exchange is essential for network security. It is not difficult to design simple and seemingly correct solutions for it, however, many such 'solutions' can be broken. We give some examples of such protocols and we show a useful methodology which can be used to break many protocols. In particular, we break a protocol that is being standardized by the ISO.We present a new authenticated exchange protocol which is both provably secure and highly efficient and practical. The security of the protocol is proven, based on an assumption about the the cryptosystem employed (namely, that it is secure when used in CBC mode on a certain message space). We think that this assumption is quite reasonable for many cryptosystems, and furthermore it is often assumed in practical use of the DES cryptosystem. Our protocol cannot be broken using the methodology we present (which was strong enough to catch all protocol flaws we found). The reduction to the security of the encryption mode, indeed captures the non-existence of the exposures that the methodology catches (specialized to the actual use of encryption in our protocol). Furthermore, the protocol prevents chosen plaintext or ciphertext attacks on the cryptosystem.The proposed protocol is efficient and practical in several aspects. First, it uses only conventional cryptography (like the DES, or any privately-shared one-way function) and no public-key. Second, the protocol does not require synchronized clocks or counter management. Third, only a small number of encryption operations is needed (we use no decryption), all with a single shared key. In addition, only three messages are exchanged during the protocol, and the size of these messages is minimal. These properties are similar to existing and proposed actual protocols. This is essential for integration of the proposed protocol into existing systems and embedding it in existing communication protocols.

/pdf/systematic-design-of-two-party-authentication-protocols-2odg01kwhc.pdf

Systematic Design of Two-Party Authentication Protocols

The authors extend the use of traditional point-to-point message authentication to multireceiver and/or multisender scenarios. They provide efficient cryptographic authentication methods for point-to-multipoint communication, where a single sender can broadcast (multicast) only one unconditionally secure authenticator for a message and which all receivers can verify. They further develop multipoint-to-point communication (incast) in which any subset (of a specified size) of a group of individuals can transmit a single authenticator (or a signature) for a message using the group's key. This method has been called threshold authentication. It is an application layer that is transparent to the receiver which only deals with the group as one entity. The bandwidth, computations, and storage overheads are reduced substantially when compared with the traditional approach. Threshold authentication hides some aspects of the internal structure of the group, which may be important in interenterprise communication. >

Multi-receiver/multi-sender network security: efficient authenticated multicast/feedback

http://www.cs.utsa.edu/~korkmaz/citations/PapersCitingMe/Banerje02.pdf

Comparative analysis of path computation techniques for MPLS traffic engineering

In this paper, we analyze the security of IPsec against a class of attacks known as the IV attacks, which are based on modifying the initialization vector (IV) of a CBC-encrypted packet during transmission. We show that IV attacks can be a serious threat for IPsec if IPsec is not used carefully. We also discuss the defense methods against these attacks.

Initialization vector attacks on the IPsec protocol suite

Specifications of encryption-based protocols using conventional and public-key encryption schemes are discussed for authentication of users or systems in a computer network environment. The protocols treat a sender and a receiver symmetrically and make no assumption about any specific time ordering of events. We apply state machine modeling and analysis techniques to determine important properties of these protocols including completeness, deadlock freeness, livelock or tempo-blocking freeness, termination, boundedness, and absence of non-executable interactions.

Deepinder P. Sidhu

Papers

Comparative analysis of path computation techniques for MPLS traffic engineering

Initialization vector attacks on the IPsec protocol suite

Authentication protocols for computer networks: I

Analysis of Routing and Wavelength Assignment in Large WDM Networks

Probabilistic optimization techniques for multicast key management