Patent ID: 7730309

Claim:
A method, comprising: negotiating in a media path a cryptographic key exchange between a first user and a second user to compute session keys for Secure Real Time Protocol (SRTP) Voice Over Internet Protocol (VOIP) media streams; computing a Short Authentication String (SAS) from the cryptographic key exchange between the first user and the second user, wherein computing includes computing the SAS in such a manner as to constrain a Man-In-The-Middle attack to one guess; displaying the SAS to the first user and the second user such that an SAS mismatch indicates existence of a Man-In-The-Middle attack; caching cryptographic key material created by the first user and the second user in a first communication session; invoking the cryptographic key material in a second communication session between the first user and the second user, thereby establishing key continuity; and augmenting cryptographic key material in the second communication session between the first user and the second user with the cryptographic key material from the first communication session.