On Digital Signatures and Public-Key Cryptosystems.

Abstract : It is shown that the single operation of raising a number to a fixed power modulo a composite modulus is sufficient to implement digital signatures: a way of creating for a (digitized) document a recognizable, unforgeable, document-dependent digitized signature whose authenticity the signer can not later deny. An electronic funds transfer system or electronic mail system clearly could use such a scheme, since the messages must be digitized in order to be transmitted.