You're using the wrong key. The public key encrypts the message so that the only person who can decrypt it is the one who has the private key. Generally, that's the guy who gave you the public key, since otherwise getting an encrypted message from you won't do him any good w/o that private key. :)And no, you cannot decrypt your own messages after you've encrypted it. Once it's encrypted, only the guy with the private key can decrypt it. To be clear, that means no one should ever, ever have your private key. If you ever make a key pair, you pass out the public key like vendors do, and guard the private key with your life and use that to decrypt messages to you.That's why if you want the vendor to encrypt his answer back to you, you include your own public key in your message to them :)