> From: owner-openssl-us...@openssl.org On Behalf Of Salz, Rich > Sent: Monday, 17 December, 2012 00:01
> >Can you be a bit more specific about what you mean by "being > used"? By default OpenSSL can use any built in ECC curve > though it can be limited in range by those of the peer. > To be more exact, for SSL/TLS protocol: - the curve used for authenticating with an ECDSA cert, and verifying that authentication, is the curve of the key in the cert. As the authenticator you know your own cert already. As the verifier you can get the cert and look at it. - the curve used for ECDH-E or A-ECDH key exchange by server is the key.group configured by SSL_[CTX_]set_tmp_ecdh or the callback configured by SSL_[CTX_]set_tmp_ecdh_callback IF this curve is acceptable to the client. If it's not acceptable, ECDH ciphers are just skipped, and unless you have a second cert configured for other kx type acceptable to the client, handshaking fails with "no shared cipher". You should be able to know what you configured. - the curve used for ECDH-E or A-ECDH by client is the curve selected by the server. This is the one place the API doesn't handle, although it looks to me like you can poke around in ssl->cert->peer_ecdh_tmp (not tested, and if it works not guaranteed in future versions, but may be a workaround). For anything other than SSL/TLS protocol, like CMS/SMIME or ssh or IPsec or g-d knows what, you'll need to say more. ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
