Encryption method that reduces the cipher text to a single byte Has anyone encountered an encryption method that compresses the cipher text to a single byte at the expense of inflating the key. If yes does it have a practical use?
Single byte, no? How about 16 bytes? Sure. Encrypt using AES-128 with a random key. The key is now the "ciphertext" and the output of the encryption (what we normally call the ciphertext) is now the "key". Problem is, how do you distribute the "key"?

The thing is, from a real world perspective, the idea of shrinking the ciphertext and growing the key is a non-starter. Keys must be shared over a secure channel, ciphertexts do not. If you had a secure channel that was efficient enough to share large amounts of data, why not just share the plaintext directly over that channel and skip the whole encryption business?