On 10/23/05, Travis H. <solinym@gmail.com> wrote:
My understanding of the peer-to-peer key agreement protocol (hereafter p2pka) is based on section 3.3 and 3.4.2 and is something like this:
A -> B: N_ab B -> A: N_ba B -> A: Sign{f(N_ab)}_a A -> B: Sign{f(N_ba)}_b A -> B: Sign{A, K_a}_SKYPE B -> A: Sign{B, K_b}_SKYPE A -> B: Sign{R_a}_a B -> A: Sign{R_b}_b
Session key SK_AB = g(R_a, R_b)
But what you have shown here has no encryption, hence no secrecy. Surely RSA encryption must be used somewhere along the line. The report doesn't say anything about the details of how that is done. In particular, although it mentions RSA signature padding it says nothing about RSA encryption padding. Is it possible that Skype doesn't use RSA encryption? Or if they do, do they do it without using any padding, and is that safe? CP