New answers tagged symmetric
CAST5 seems to be a solid 64-bit block cipher with 128-bit key. As far as I can tell after a short literature search, it's definition is sound and unbroken, despite nearly two decades of exposure (more for the round function). CAST5 is also known as CAST-128, defined in RFC 2144 (1997), and endorsed by ISO/IEC 18033-3:2010 (current). It is a 16-round ...
The general answer is "no, you can't authenticate someone over a wire unless they know some secret information." The only way to authenticate someone is to have them do something that no one else can do. If you're trying do to it by just sending messages between the parties, the only way I can do something that someone else can't is if I know something they ...
There are libraries allowing to do that: PBC: C library JPBC : Java library Hope it helps.
Vigenere matches the description, though its security problems when the key is shorter than the message are well known.
I call an algorithm meeting this spec "rolling xor". It's only strong at the one-time-pad level though.
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