I was bit by not having the right root CA certificates for Authorize.net's new Entrust-originated SHA2 certificate on secure.authorize.net. Using ruby net/https produced this OpenSSL error:
/usr/local/lib/ruby/1.8/net/http.rb:586:in `connect': SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (OpenSSL::SSL::SSLError)
They made a blog post about it:
and claim that you should have: