Digitally Signing For Something, And Checking Without Revealing The Message … Meet AAI Encryption
Normally when we digitally sign something, we have to create a hash of the data, and then use the public key of the recipient to encrypt it. With signcryption we sign something at the same time as encrypting it. Ahmad-Afzal-Iqbal (AAI) [1] encryption implements signcryption using elliptic curves and is designed for Alice to send a signature to a firewall in order for it to check the signature. If valid, the firewall validates the signencryption cipher to Bob. Overall the firewall never has to see the ciphertext (C) and only works on the signature element (R,S). The paper can be viewed here.
Within a signature, such as with ECDSA and EdDSA, we take a hash of the message (m), and generate to part of a signature: R and S. These values can then be checked against the message (m). With the AAI method, a firewall can check the validity of the signature using the R and S values, but not requiring the ciphertext to check against the message. Within this, we just need some form of identity for Bob and Alice. Initially, Bob and Alice have something the defines their identity (ID_B and ID_A), and then generate their own…
