1Password
Client should show proof first
According to the SRP design specification, you reference the client should show it's proof first. However in the ClientProof() you check if the server is proved first?
if !s.isServer && !s.isServerProved {
return nil, fmt.Errorf("don't construct client proof until server is proved")
}
Ah. I assume you are referring to
Now the two parties have a shared, strong session key K. To complete authentication, they need to prove to each other that their keys match. One possible way:
User -> Host: M = H(H(N) xor H(g), H(I), s, A, B, K)Host -> User: H(A, M, K)
I probably read that backwards. I do not believe that this matters at this point in the authentication process, but unless I am certain that order doesn't matter here, we should have this code follow that "spec".
Yes and the comment at the top of the file also mentions client proof first
Client -> Server: M = H(H(N) xor H(g), H(I), s, A, B, Key) Server >- Client: H(A, M, K)
The client must show its proof first
I believe in most cases server proof is not required or at least for my use case, I am only interested in the client proof so this adds an additional round trip to the authentication process.