If your cipher were secure, this image wouldn't have repeating patterns (2015)

Re:If your cipher were secure, this image wouldn't have repe... by cryptonector on Saturday February 29, 2020 @01:49AM (#22449331)

"Can" as in "you could possibly do it, yeah", and "shouldn't" as in "really, really, REALLY shouldn't". The Venona cable decrypts were made possible by one-time pad reuse.

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Re:If your cipher were secure, this image wouldn't have repe... by klingonopera on Saturday February 29, 2020 @01:52AM (#22449337)

I'm not sure, definitely not if you use XOR-OTP, not so sure about additive-OTP, see my reply here[0] for reasons.

Would like to know, if my assessment on additive OTP is correct, if anyone knows?

EDIT: I mean, of course you still shouldn't, but where the XOR catastrophically fails after just a single reuse, the additive one should be more robust, even with reuse. The Venona Decrypts were additive-OTP, I postulate, the decryption rate would've probably been higher with XOR-OTP.

[0]: https://news.ycombinator.com/item?id=22448966

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Re:If your cipher were secure, this image wouldn't have repe... by numpad0 on Saturday February 29, 2020 @09:10AM (#22450617)

I thought the notion of OTP is that there is absolutely nothing to decode, prove or disprove ciphertext?

Like if ciphertext is "supersecret" then it feels like plaintext can't be more obvious and OTP must be "00000000000", but there's nothing anywhere to logically/mathematically support it. OTP could be something else and plaintext could be "hackernews" or "ycombinato".

In reality a simple XOR with a random sequence preserve enough entropy of data that I've heard you could make out voices if used on media, so payloads must be scrambled, but that's not recovery, only a guess. ANY reuse breaks that notion and make it not an OTP cryptography.

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