We combine well-known techniques from the areas of error-correcting codes and cryptography to achieve a new type of cryptographic primitive that we refer to as a fuzzy commitment scheme. Like a conventional cryptographic commitment scheme, our fuzzy commitment scheme is both concealing and binding: it is infeasible for an attacker to learn the committed value, and also for the committer to decommit a value in more than one way. In a conventional scheme, a commitment must be opened using a unique witness, which acts, essentially, as a decryption key. By contrast, our scheme is fuzzy in the sense that it accepts a witness that is close to the original encrypting witness in a suitable metric, but not necessarily identical.This characteristic of our fuzzy commitment scheme makes it useful for applications such as biometric authentication systems, in which data is subject to random noise. Because the scheme is tolerant of error, it is capable of protecting biometric data just as conventional cryptographic techniques, like hash functions, are used to protect alphanumeric passwords. This addresses a major outstanding problem in the theory of biometric authentication. We prove the security characteristics of our fuzzy commitment scheme relative to the properties of an underlying cryptographic hash function.

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A fuzzy commitment scheme

Protocols for authentication and key establishment are the foundation for security of communications. The range and diversity of these protocols is immense, while the properties and vulnerabilities of different protocols can vary greatly.This is the first comprehensive and integrated treatment of these protocols. It allows researchers and practitioners to quickly access a protocol for their needs and become aware of existing protocols which have been broken in the literature.As well as a clear and uniform presentation of the protocols this book includes a description of all the main attack types and classifies most protocols in terms of their properties and resource requirements. It also includes tutorial material suitable for graduate students.

Protocols for Authentication and Key Establishment

Radio-frequency identification devices (RFID) may emerge as one of the most pervasive computing technologies in history. On the one hand, with tags affixed to consumer items as well as letters, packets or vehicles costs in the supply chain can be greatly reduced and new applications introduced. On the other hand, unique means of identification in each tag like serial numbers enable effortless traceability of persons and goods. But data protection and privacy are worthwhile civil liberties. We introduce a simple scheme relying on one way hash-functions that greatly enhances location privacy by changing traceable identifiers on every read getting by with only a single, unreliable message exchange. Thereby the scheme is safe from many threats like eavesdropping, message interception, spoofing, and replay attacks.

Hash-based enhancement of location privacy for radio-frequency identification devices using varying identifiers

A secure distributed single-login authentication system comprises a client and a server. The client collects a user name and password from a user and tests that user name and password at a variety of potential authentication servers to check where the login is valid. It combines the password with a time varying salt and a service specific seed in a message digesting hash and generates a first hash value. The client sends the hash value along with the user name and the time varying salt to a currently selected server. The server extracts the user name and looks up an entry under the user name from the selected server's database. If an entry is found, it retrieves the password and performs the same hash function on the combination of the user name, the service specific seed, and the retrieved password to generate a second hash value. Then, it compares two hash values. If these two values match, the user is authenticated. In this way, the system never sufficiently reveals the password to authentication agents that might abuse the information.

Simple, secure login with multiple authentication providers

An attack is demonstrated on a previously proposed class of key agreement protocols. Analysis of the attack reveals that a small change in the construction of the protocols is sufficient to prevent the attack. The insight gained allows a generalisation of the class to a new design for conference key agreement protocols.

On Key Agreement and Conference Key Agreement

We give a new definition of keyed hash functions and show its relation with strongly universal hash functions and Cartesian authentication codes We propose an algorithm for a secure keyed hash function and present preliminary result on its performance The algorithm can be used for fast (about twice the speed of MD5) and secure message authentication

Keyed Hash Functions

This is a proposal on the construction of a Message Authentication Code (MAC) based on Latin Squares The design is inspired by Wegman-Carter construction which takes advantage of provable security The MAC is described and its security is examined It is also compared with other MACs and its advantages are shown

A Message Authentication Code Based on Latin Squares

This paper presents an attack on Anderson and Lomas's proposed password-based authenticated key exchange protocol that uses collisionful hash functions The weaknesses of the protocol when an old session key is compromised are studied and alternative solutions are given

On password-based authenticated key exchange using collisionful hash functions

This paper presents an attack on Gong's proposed collisionful hash function. The weaknesses of his method are studied and possible solutions are given. Some secure methods that require additional assumptions are also suggested.

Shahram Bakhtiari

Papers

Keyed Hash Functions

A Message Authentication Code Based on Latin Squares

On password-based authenticated key exchange using collisionful hash functions

On selectable collisionful hash functions

On the Weakness of Gong's Collisionful Hash Functions.