MMX is a new technology to accelerate multimedia applications on Pentium processors. We report an implementation of IDEA on a Pentium MMX that is $1.65$ times faster than any previously known implementation on the Pentium. By parallelizing four IDEA's we reach an unprecedented $78$ Mbits/s throughput per output block on a 166MHz MMX. In the light of rapidly increasing popularity of multimedia applications, causing more dedicated hardware to be built, and observing that most of the current block ciphers do not benefit from MMX, we raise the problem of designing block ciphers (and encryption modes) fully utilizing the basic operations of multimedia.

this article particularly interesting. Perhaps the most remarkable cryptanalytic developments over the last year or two have been the advances made in the analysis of hash functions by Hans Dobbertin. The net result of this work has been a lack of options in the hash functions that are available for long-term use. In Europe, however, RIPEMD-160 has been gaining in popularity and the designers of this algorithm provide us with a summary of its features in this issue of the newsletter. Finally, at the 1997 Crypto conference attendees honored the work of Oded Goldreich. As one of the pioneers in establishing a theoretical framework to today's cryptography Oded's invited lecture was one of the highlights of the conference. In our lead article Oded provides us with his perspective on the foundations of modern cryptography. The future success of CryptoBytes depends on input from all sectors of the cryptographic community, and as usual we would like very much to thank the writers who have contributed to this second issue of the third volume. We encourage any readers with comments, opposite opinions, suggestions or proposals for future issues to contact the CryptoBytes editor at RSA Laboratories or by E-mail to bytes-ed@rsa.com. CRYPTOBYTES T H E T E C H N I C A L N E W S L E T T E R O F R S A L A B O R A T O R I E S --- A U T U M N 1 9 9 7 3

Nested certificates [3,4] are proposed as certificates for other, subject, certificates. However, any malicious modification over the subject certificate cannot be located by the verification of it via a nested certificate. This integrity control problem can be solved by employing one way hash functions. In this paper, two integrity control methods for the subject certificate verification are described. Their relative advantages and disadvantages are also discussed. 1.

RIPEMD-160 is a fast cryptographic hash function that is tuned towards software implementations on 32-bit architectures. It has evolved from the 256-bit extension of MD4, which was introduced in 1990 by Ron Rivest [20, 21]. Its main design feature are two different and independent parallel chains, the result of