Information-Revealing with Distributed Escrow Authorities

This paper present an alternative scheme to key escrow scheme which allows probabilistic law enforcement access to reveal the encrypted communications. Namely, key escrow authority can reveal the information between communication parties partially. Our scheme allows law enforcement access with probability p for each message. The scheme in this paper is basically the complemented scheme of Mihir Bellare and Ronald L. Rivest [2], and combine a publicly verifiable encryption technique and translucent cryptography based on non-interactive fractional oblivious transfer. This protocol allows such access with probability for each message, for a parameter between 0 and 1, which should be chosen to provide an appropriate balance between concerns for individual privacy and the need for such law enforcement access by government. This paper induct a set of distributed key escrow authorities(DEA). The scheme is based on the El-Gamal encryption, a proof scheme of knowledge of common exponent in publicly verifiable El-Gamal public-key encryption, and a set of distributed escrow authorities. In session key recovery phase by DEA, use only partial parameters from each key escrow authorities required for session key recovery that have been passed through zero-knowledge(ZK) interactive proof protocol. The scheme allows both the law enforcement access with probability and DEA to recover the session key used to encrypt communication by User A.