I'm trying to sign a contract with another party, without using handwritten signatures. I've just read through Applied Cryptography, but there doesn't seem to be a protocol that can solve this ...
Bob wants to send a message to Alice, such that Alice can be sure that the message came from Bob, but can't prove it to anyone else. If I understand right, this means that the same message could have ...
A message may be accompanied with a digital signature, a MAC or a message hash, as a proof of some kind. Which assurances does each primitive provide to the recipient? What kind of keys are needed?