Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
-1
votes
2answers
166 views
Cryptographic Symmetric Stream Cipher
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 ...
1
vote
1answer
69 views
Requiring a “supervisor” key pair and a “user” key pair to decrypt multiple-recipient messages
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)
...
0
votes
0answers
55 views
Perfect secrecy Proof
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 ...
