# Which ciphers produce random ciphertext?

I already know AES produces a "random" output.
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Its ciphertext doesn't follow a pattern and is indistinguishable from noise.

Is this common for most ciphers?

• wikiwand.com/en/Ciphertext_indistinguishability#/… – user2398029 Jan 16 '16 at 0:01
• I removed the question about ciphers in general, because it is too broad (Google will give you lists of ciphers if you need them) and not answered in the answer you already accepted. If you can phrase in in a more answerable fashion, you might want to ask about it separately. – otus Jan 16 '16 at 8:58
• FYI: cross-posted on sec.se – SEJPM Jan 16 '16 at 19:39

Strictly speaking, we can't know for sure that the output of AES is indistinguishable from random noise. It's conjectured to be true but no "proof" of that fact exists.

For most commonly-used ciphers, it is conjectured that their output is indistinguishable from random. Specifically, modern ciphers are conjectured to be "strong pseudorandom permutations", which means that an adversary given encryption and decryption oracles for the cipher can't distinguish it from a random permutation.