[gnutls-devel] gnutls_certificate_verify_peers* question
nmav at gnutls.org
Tue Feb 19 13:05:33 CET 2013
On Tue, Feb 19, 2013 at 10:10 AM, Jaak Ristioja <jaak.ristioja at cyber.ee> wrote:
> If I use the gnutls_certificate_verify_peers2() or
> gnutls_certificate_verify_peers3() functions in the callback set using
> gnutls_certificate_set_verify_function(), do those functions also verify
> that the peer has the private key corresponding to the public key in the
> certificate, or is it done elsewhere outside of the callback?
For simplicity I'll focus on the signing ciphersuites. In that case,
during the handshake you receive a message from the peer that contains
handshake parameters (it is the random nonces and DH params in server
side) that are signed. This message is verified in gnutls_handshake()
directly (i.e. you have no say on that). If that succeeds the callback
takes control and verifies whether the parameters (i.e. the
certificate) used in the previous signature verification are
> The goal is to setup a connection, where both endpoints authenticate
> only using their key pairs (i.e. give access iff peer has public key A;
> ignoring any certification chain) and I'm wondering whether calling a
> gnutls_certificate_verify_peers* function is needed at all.
If you need authentication of the peers and/or verify the name of the
peer, then they are needed. If you use fixed public keys, that would
be the place to verify that they correspond to the expected ones.
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