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.
The demand for security services requiring cryptography is now sufficiently widespread to make appropriate security APIs increasingly valuable tools in the design of secure systems. We will examine some of the APIs currently under development, like GSS-API, and argue that the designers of such APIs have to be explicit about the key management issues relevant to their interfaces.
We present an application of quantum cryptography with faint-pulse interferometry for smart-cards.
The Escrowed Encryption Standard (EES) proposed by U.S. government has gained much attention in the last two years. It was claimed that EES can provide cryptographic protection to unclassified, sensitive data, while at the same time, allow for the decryption of encrypted messages when lawfully authorized. Later, some criticism was proposed to reveal the weakness of the EES proposal. In this paper we propose a new key escrow cryptosystem. The system eliminates many known weaknesses of the EES proposal. Particularly, the new system strengthens the weakest part of the EES proposal, i.e., the checksum generation, and provides other benefits that the original EES proposal did not have.
Four server-aided secret computation protocols, Protocols 1, 2, 3, and 4, for modular exponentiation were proposed by Kawamura and Shimbo in 1993. By these protocols, the client can easily compute the modular exponentiation M(d) mod N with the help of a powerful server, where N is the product of two large primes. To enhance the security, the client was suggested to use a verification scheme and a slight modification on each proposed protocol. In this paper, we propose two new active attacks to break Protocols 3 and 4, respectively. Even if Protocols 3 and 4 have included the slight modification and verification, the untrusted server can still obtain the secret data d. The client cannot detect these attacks by the proposed verification. To adopt these new attacks, the difficulty of finding the value of the secret data d will be decreased drastically.
