Thread: one time pad breakable debate

Originally Posted by Mario F.

But the seed is not the key. Hence why I put it in double quotes. The key will be generated by the seed. The mechanism for said generation is an RNG. Meaning the actual key can be generated on the fly and the decryption is made right after, as long as:

a) you possess the correct seed
b) you possess the correct RNG
c) you possess the correct decryption algorithm

According to Kerckhoffs' principle, the attacker knows the PRNG and decryption algorithm.

What you described is a possible use of a PRNG to implement a stream cipher. This can be secure with the use of a cryptographically secure PRNG, but it does not have the property of being unbreakable like a one time pad. By observing sufficient ciphertext, it is theoretically possible to determine the state of the PRNG, and thus break the encryption.