Secret Key Cryptography

Full Title or Meme

In Secret Key Cryptography two parties that wish to communicate have some method for creating pre-shared secrets which can be used to hide subsequent communications from others.

Context

• At least since the time of Julius Cesar there have been methods know to hide messages from prying eyes.
• During the age of computer communications, it became possible to have real-time communications that was also:

1. Hidden from external eavesdroppers.
2. Protected from alternation with digital message authentication.

Problem

A shared secret is not really a secret any longer as either side gets to decide when to release the key and expose the communications, or allow fraudulent messages to be created, even long in the past.