Abstract: A method and system for verifying the identity of a computer network node is provided. As part of the session initiation process between two partner nodes planning to exchange sensitive encrypted data, the node receiving data generates and encrypts a session key which is transmitted to the node sending data. At the sending node, the low order four bytes of the encrypted session key are saved for authentication of the receiving node. The encrypted session key is returned to the receiving node as session set-up continues. The receiving node concatenates the low order four bytes of the encrypted session key with four bytes of pseudorandom data to form an initial chaining value which is then encrypted and transmitted to the sending node. The sending node recovers the initial chaining value and compares the low order four bytes of this value with the low order four bytes of the encrypted session key previously saved. If the values are the same, authentication of the receiving node is established.