SSL握手后如何获取密码签名？

Question

I'm making a DTLS client-server program with openssl. The program works fine, but I can't find a way to get the cipher signature after SSL handshake.

By after SSL handshake, I mean in the client side, after:

if (SSL_connect(ssl) <= 0)
{
    //error handling 
}

In the server side, after:

do 
{
    ret = SSL_accept(ssl);
} while (ret == 0);

I can see the actual cipher signature is sha256WithRSAEncryption from the captured DTLS packets, but how to get this information from openssl?

Note that even though I'm using DTLS protocol, the code is almost the same as TLS/SSL.

Answer 1

Cipher algorithm used is stored in a certificate. So when you have a certificate (x509), the type of cipher algorithm can be extracted. Numeric version only:

X509_get_signature_type(client_cert)

To get human readable string, convert the return value of the previous function with this:

OBJ_nid2ln(X509_get_signature_type(client_cert))