What are the security vulnerabilities of the XOR operator in the following scenario:
- The Key, The Cyphertext and the Plaintext are the same size in bits.
- The Key is only used once and it's secret
- The Plaintext is only used once and it's secret
- Hence the Cyphertext is only used once, but it's public
- Only the Cyphertext, and hence the size of the key is known to the adversary
- The Key was generated by a pseudorandom number generator
- The Plaintext (which is a private key to something else) was also generated by a pseudorandom number generator
Therefore neither the key nor the plaintext is fully random, vulnerable to frequency attacks.
So I don't care about practical issues, like the difficulty of key sharing. I only care about security issues.
We can identify that this setup can be vulnerable to frequency analysis and such described here:
- But are there other vulnerabilities besides the pseudo-random nature of the key and the plaintext?
- If both the key and the plaintext were truly random, would this provide perfect secrecy?