Permanent reencryption: How to survive generations of cryptanalysts to come

Abstract

The protection of long-lived sensitive information puts enormous stress on traditional ciphers, to survive generations of cryptanalysts. In addition, there is a continued risk of adversaries penetrating and attacking the systems in which these ciphers are implemented. In this paper, we present our work-in-progress on an approach to survive both cryptanalysis and intrusion attacks for extended periods of time. A prime objective of any similar work is to prevent the leakage of plaintexts. However, given the long lifespan of sensitive information, during which cryptanalysts could focus on breaking the cipher, it is equally important to prevent leakage of unduly high amounts of ciphertext. Our approach consists in an enclave-based architectural set-up bringing in primary resilience against attacks, seconded by permanently reencrypting portions of the confidential or privacy-sensitive data with fresh keys and combining ciphers in a threshold-based encryption scheme.