Talk:Cryptography/Public Key Overview

This is the double lock principle, but it is not not Public Cryptography as both key are secret. In public cryptography one key is public, the other is secret. Nobody knowing the public key, is able to decipher a message encrypted with a public key. Only the secret key is able to decipher a message encrypted with a public key.

So someone (Alice) is able to send securely an encrypted data to Bob, if Bob had made his key public.

Bob is able to prove that he owns a secret key only by providing:
 * a plain text
 * the same text crypted with the secret key
 * the public key corresponding to the secret key.

Something similar to the double lock principle is Merkle's puzzle, which is the ancestor of the Diffie-hellman key exchange, which is itself a close cousin to RSA public key system.