A key agreement protocol for P2P VoIP applications

A crucial aspect when establishing a secure peer-to-peer communication channel is the negotiation of the security parameters used to protect the successive data communications, including the various encryption and authentication keys. There are different secure protocol (such as IPSec, TLS, SSH, etc.) currently defined with their own negotiation mechanisms; unfortunately they usually rely on a pre-established trust relationship or secure association based on a shared secret key, some digital certificates, or a public key infrastructure (PKI). In this work we propose a new alternative key agreement protocol for setting up multimedia sessions between user agents (UAs) without requiring any pre-shared key or trust relationship or PKI. When two UAs communicate for the first time, a new key is established through Diffie-Hellman algorithm and authenticated by end users through vocal reading of a short authentication string. The proposed protocol has been also implemented and integrated in a publicly available VoIP UA.