tlsSocket.getProtocol()

tlsSocket.getProtocol()

Returns a string containing the negotiated SSL/TLS protocol version of the current connection. 'unknown' will be returned for connected sockets that have not completed the handshaking process. null will be returned for server sockets or disconnected client sockets.

Examples:

'SSLv3'
'TLSv1'
'TLSv1.1'
'TLSv1.2'
'unknown'

See https://www.openssl.org/docs/manmaster/ssl/SSL_get_version.html for more information.