>Maybe the idea you are really looking for isn't "prevent it from being encrypted", but instead, "make any 'simple' reversible transformation of it, have parts that hint at a way to decode it / leave it still decodeable by some algorithm" ?
yes, but in such a way that the original message is recoverable even if it gets encrypted.
I should have said, that I'm thinking classically and that I'm thinking about key-based encryption, i.e. no one-time pads and the key has to be smaller than the message.
> if you are allowed to encode your messages in ways that make them really gargantuan and much larger than could ever be practical, then, I think this could be done ?
Yea, I think this may be unavodiable in any way this is done. The encoded message will be much bigger than the plain text.
Which also makes it reasonable to expect this to work only against key-based cyphers.
I don't undesrtand why you compare the complexity of the message and the complexity of the machines doing the cyphering (either en- or de-cryption), but regardless, thanks for the response.
The key issue here is that it really has to be much bigger, merely a hundred times or million times bigger is definitely not going to be sufficient.
There indeed is a limitation of key-based algorithms that encrypting too many blocks with a certain structure may make them vulnerable; however, that limitation is quite large unless you're using older/smaller algorithms like DES. I couldn't remember or quickly find what the circumstances are for e.g. AES-128 but IIRC it might be something like 2^48 blocks so for your approach to work, you'd have to stretch each block of content (e.g. 16 bytes) into petabytes of encoded data before you start having a theoretical chance to decode it; and for AES-256 it would probably be that amount squared, and you simply can't encode or store 2^96 blocks of anything.
yes, but in such a way that the original message is recoverable even if it gets encrypted.
I should have said, that I'm thinking classically and that I'm thinking about key-based encryption, i.e. no one-time pads and the key has to be smaller than the message.
> if you are allowed to encode your messages in ways that make them really gargantuan and much larger than could ever be practical, then, I think this could be done ?
Yea, I think this may be unavodiable in any way this is done. The encoded message will be much bigger than the plain text. Which also makes it reasonable to expect this to work only against key-based cyphers.
I don't undesrtand why you compare the complexity of the message and the complexity of the machines doing the cyphering (either en- or de-cryption), but regardless, thanks for the response.