Encoded text, text that is unreadable.

plural of ciphertext

(cryptography) An attack on a cryptosystem that relies only on the attacker's knowledge of some ciphertexts encrypted with that system and key. Less powerful than a known-plaintext attack.

(cryptography) An attack on a cryptosystem that relies on the attacker's ability to choose any ciphertext of their liking and decrypt it into the corresponding plaintext with that system and key. More powerful than a chosen-plaintext attack.