user54238: I have private key. How can I get passphrase for my bitcoin address.

user27931: Assuming you have a symmetrically encrypted copy of your private key, where the encryption key was derived from a passphrase, you would be trying to perform a known-plaintext attack. However, it should not be possible in polynomial time for a proper AES implementation, so I'm afraid you're out of luck.

54238: <p>I have private key. How can I get passphrase for my bitcoin address.</p>
 27931: <p>Assuming you have a symmetrically encrypted copy of your private key, where the encryption key was derived from a passphrase, you would be trying to perform a <a href="http://Known-plaintext%20attack" rel="nofollow noreferrer">known-plaintext attack</a>. However, it should not be possible in polynomial time for a proper AES implementation, so I'm afraid you're out of luck.</p>
