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Comment by Ghjklov | Hacker News Reader

This is only vaguely related, but when I was younger I used to imagine a way for two people to communicate in secret openly without too much effort. Basically, person A will write messages to forum 1 under a decided alias and person B will respond to those messages on forum 2 under their decided alias. Two different forums, completely unrelated to each other, but only the two people will know where to look for the corresponding answer. To anyone else, it may look like total nonsense but if they hide it within posts that are vaguely on-topic, it could fly by with no one noticing at all.

Edit: Improved wording

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Actually i had a better version of this:

Person A: says "hello Joe" Person B: answers: "Great to see you again buddy!"

After posting message, sender hashes his message with secret salt: "hello Joe" -> 2959D03A72B897C and then posts secret, real text to https://secret-share/#2959D03A72B897C

Receiver does the same to read the actual message.

Fun part?

Sender and receiver can actually piggyback on other people's conversations, twitter feeds, newpaper headlines this way to hide secret messages.

I like that a lot. And we are just two random people with random ideas. Just imagine the variety of ways people are already secretly communicating right now right in the open and none of us are any wiser.

Absolutely.

The best way to hide the secret is to make adversary believe that secret does not exist

That's quite clever. In crypto literature, I guess it could be called like "covert cross-channel".

It turns out that the idea itself of communicating secrets in plain sight is called "subliminal channel" [1], which differs from steganography (hiding a message inside another message).

My question is not meant to imply conspiranoia. It's whether we as an audience of online forums have been fooled by this technique at some point.

[1] https://www.emsec.ruhr-uni-bochum.de/media/crypto/attachment...

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