Digital Signature on Voice Stream in IP Phone

R. Uda, M. Ito, S. Ichimura, K. Tago, T. Hoshi, and Y. Matsushita (Japan)


Computer Networks and Communications, Network Security, VoIP, Authentication


A proposal of digital signature for voice data of IP phone is described in this paper. The objective of this study is not confidentiality such as IPSec, but authentication of voice data. In our method, a speaker cannot deny what he or she has said, while a listener cannot revise what the speaker said. In Japan, a public-key based digital signature makes documents legally valid as a physical signature or one's seal does. However, a digital signature requires a large calculation cost. The proposed method reduces the calculation load by using not only a public key signature but also a hash function. The phones employing this method authenticate voice data in a P2P system without any connection via a server, and the authentication has tolerance to packet loss and delay. One of the implementations of the proposal adopts G.711. It can work on the existing IP phone infrastructure and on PKI.

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