Secrecy by interpretation functions

This paper presents a novel approach to verify the secrecy property of cryptographic protocols. Basically, the idea is to establish sufficient conditions under which the secrecy property of a given protocol is guaranteed. The idea behind the sufficient conditions is to restrict the principals involved in the analyzed protocol so that they never decrease the security level of any piece of information when they send it over the network. For example, a principal is not allowed to protect a “top secret” information by a secret or a public key. Only keys having a security level greater or equal to “top secret” can protect “top secret” information. The proposed conditions can be syntactically verified on a cryptographic protocol in acceptable time. This proposed approach is general in the way that it can be applied to any cryptographic protocols and with any set of security levels (the set {public, secret, topSecret}, or the set {0,1}, etc).