HTTPS TLSv1.2 Client-Auth negotiation

[Ben Arnold]

Hi,

I am using libcurl and OpenSSL to communicate with various webservers, most of 
which require client authentication.  I am having trouble connecting to one 
server that requires TLSv1.2.  After the server has sent a Certificate Request, 
OpenSSL sends up the client cert (I think) and the server replies with a 
Decrypt Error alert.  The messages that are sent to the server are (as decoded 
by Wireshark):
                Client Key Exchange
                Client Key Exchange
                Certificate Verify
                Change Cipher Spec
                Encrypted Handshake Message

The first CKE is 1456 bytes long, which I suspect means it includes the 
certificate as the PreMaster is only 258 bytes.

I am wondering if this is something to do with TLSv1.2, all of the other 
servers I connect to are happy with TLSv1.

If I use the cURL command line tool then it works:

...
* SSLv3, TLS handshake, Request CERT (13):
* SSLv3, TLS handshake, Server finished (14):
* SSLv3, TLS handshake, CERT (11):
* SSLv3, TLS handshake, Client key exchange (16):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):


I have attached ClientCertFail.pcapng which shows the trace of a failure, along 
with ClientCertFail.keys which contains the keys for that session.

(btw, are the strange CKE messages from client -> server simply an artefact of 
Wireshark's decoding, or do they point to the problem?  They don't seem to 
match cURL's diagnostic output, but I can't see the network capture from cURL 
as it won't output the session keys)

Many thanks,
Ben

ClientCertFail.keys
Description: ClientCertFail.keys

ClientCertFail.pcapng
Description: ClientCertFail.pcapng