Question

I am using openssl in c to verify a certificate. Is there any way i can skip the self signed certificate error? I am getting that error for all the sites that has invalid/expired/mismatched url certificates and i am unable to detect any of the other errors.

And I use the function
SSL_CTX_load_verify_locations(ctx,0,CA_LIST)) to load CA_LIST. What does it exactly do?

Answer 1

The error self-signed certificate in certificate chain comes, when the root or self-signed certificate is present in the certificate list sent by the peer, but, the same is not loaded in your Trust Store.

The SSL_CTX_load_verify_locations(ctx,0,CA_LIST)) will try to load the CAs present in the path mentioned in CA_LIST.

The function prototype is int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *CAfile, const char *CApath);

The OpenSSL Help Page Says:

“If CApath is not NULL, it points to a directory containing CA certificates in PEM format. The files each contain one CA certificate. The files are looked up by the CA subject name hash value, which must hence be available. If more than one CA certificate with the same name hash value exist, the extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search is performed in the ordering of the extension number, regardless of other properties of the certificates. Use the c_rehash utility to create the necessary links.
The certificates in CApath are only looked up when required, e.g. when building the certificate chain or when actually performing the verification of a peer certificate.”

You can get more information from the OpenSSL Page here.