Let me know a cryptographic symmetric stream cipher system with only two functions say S() and P() and it should satisfy the following conditions: There will be two independent computers say M1 and ...
I've been toying with some encryption scenarios recently. One of the hard ones I came across is a multi-party system. So we have Bob -- The person who sends the message (and knows it's recipients) ...
A symmetric cryptosystem have perfect secrecy $\iff$ for all distribution over the messages space, $M$, and for all $m0$, $m1$ (messages) and any ciphertext $c$, $$P(c|m0) = P(c|m1).$$ I got ...