[maginx]

Agreed - I've worked with PKI in many years, and know why the various systems work...in terms of "why you can decrypt again", not in terms of why it is secure (no other way to decrypt) which no one really knows. But if we assume for a moment the systems are secure, it is truly fascinating when thinking about it in abstract terms: Who would have thought, it is possible to give someone an exact recipe to follow that scramble a message to be sent... we can consider e.g. an encryption routine where the public key is inline so it is really just a standalone scrambling problem. Even though it is completely public, it can only be used to scramble and not unscramble. The sender who literally went through the steps to scramble the message, cannot undo what they just did. (the sender could have saved the original before scrambling!). And it is not because data is thrown away it can't be unscrambled - all the information is there there, fully recoverable, but only by the person who made the scrambling-recipe and there's no practical way to deduce this unscrambling recipe from the scrambling recipe.