Scalable Key-Escrow

Abstract

We propose a cryptosystem that has an inherent key escrow mechanism. This leads us to propose a session based public verifiable key escrow system that greatly improves the amount of key material the escrow servers have to keep in order to decrypt an encryption. In our scheme the servers will only have a single secret sharing, as opposed to a single key from every escrowed player. This is done while still having the properties: 1) public verifiable: the user proves to everyone that the encryption can indeed be escrowed, and 2) no secret leakage: no matter how many decryptions a law enforcement agency is presented, it will gain no more information on the users private key, than it couldn't have calculated itself.