The most effective method for uniquely identifying the originator of electronic transactions is a digital signature. A digital signature is a cryptographic technique that uses a pair of keys, one public and one private, to authenticate the identity and integrity of the sender and the message. A digital signature is created by applying the sender’s private key to a hash of the message, and is verified by applying the sender’s public key to the signature and comparing it with the hash ofthe message. A digital signature ensures that the sender cannot deny sending the message (non-repudiation), and that the message has not been altered or tampered with during transmission (data integrity). References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 3, Section 3.2.3, page 1301