Hot answers tagged cipher
That sort of thing is known as multi-party computation, and you should use a Socialist Millionaire Protocol for your particular instance.
One time pad is definitely both easy to do and has perfect secrecy, but key management is a pain and can compromise security. Basically a Vigenère cipher with a key as long as the the message should be secure, because different keys can create ALL possible messages with equal probabilities. Again, it's a one time pad, so no KPA, CPA, or CCA security. ...
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