I didn't understand how the blind signature implementations work. But I devised my own way of doing it:Alice would compose the messageAlice would calculate the hash of the messageAlice would hand the hash to BobBob would sign it with his private keyAlice would hand the message and the signed hash to CarolCarol would calculate the actual hash using the messageCarol would decode the signed hash with Bob's public keyCarol would compare the actual hash with the decoded hashWouldn't this algorithm replace the blind signature implementation as described in Wikipedia in every case?
Is signing a message hash a valid replacement for blind signature?
cr.crypto security
Wouldn't this algorithm replace the blind signature implementation as described in Wikipedia in every case?No, because hashing is a deterministic algorithm. Let M be Alice's message, and $H(\cdot)$ be the hash function.In your algorithm, Alice passes H(M) to Bob, who can store H(M) for later reference. This way, Bob effectively creates a database of message hashes signed by him, as well as the ID of the user who asked for Bob's signature. Let $D = \{\langle H(M_1), ID_1 \rangle, \langle H(M_2), ID_2 \rangle, \ldots \}$ be this database.On seeing a message-signature pair $(M, \sigma)$, Bob hashes M to H(M), and searches D for H(M). If H(m) is found, Bob can easily recover the ID of the user. Hence, this method does not blind the identity of the user.