International Association for Cryptologic Research

International Association
for Cryptologic Research


Joy Algesheimer


How to Protect Against a Militant Spammer
Markus Jakobsson John Linn Joy Algesheimer
We consider how to avoid unsolicited e-mail -- so called spam -- in a stronger adversarial model than has previously been considered. Our primary concern is the proposal of an architecture and of protocols preventing against successful spamming attacks launched by a strong attacker. This attacker is assumed to control the communication media and to be capable of corrupting large numbers of protocol participants. Additionally, the same architecture can be used as a basis to support message integrity and privacy, though this is not a primary goal of our work. This results in a simple and efficient solution that is largely backwards-compatible, and which addresses many of the concerns surrounding e-mail communication.
Efficient Computation Modulo a Shared Secret with Application to the Generation of Shared Safe-Prime Products
Joy Algesheimer Jan Camenisch Victor Shoup
We present a new protocol for efficient distributed computation modulo a shared secret. We further present a protocol to distributively generate a random shared prime or safe prime that is much more efficient than previously known methods. This allows to distributively compute shared RSA keys, where the modulus is the product of two safe primes, much more efficiently than was previously known.