ABSTRACT
Note that as there are an infinite number of possible messages, and only a finite number of hash values, then theoretically there will be an infinite number of messages that hash to the same value. The point is that any collision should
One of the most powerful uses of hash functions is for message authentication. Suppose Alice sends a message to Bob, and Bob wants to make sure that the message he receives is really the message that Alice sent. Here’s a protocol using a symmetric cryptosystem, with a key k known to both Alice and Bob:
1. Alice hashes her message m to produce y = H(m), and encrypts y using the key k to obtain e = E(y, k).
