Encryption and Decryption provide secrecy, or confidentially, but not Integrity. One way to preserve the Integrity of a document is Through the use of Fingerprint. The electronic equivalent of the Document and Fingerprint pair is the message and message digest pair. To preserve the integrity of a message, the message is passed through an Algorithm called a hash function. The hash function creates a compressed image of the message that can be used as a Fingerprint. The two pairs document/fingerprint and message/message digest and similar, with some difference. The document and fingerprint are physically linked together; also, neither needs to be kept secret. The message and message digest can be unlinked (or sent) separately and, most importantly, the message digests needs to be kept secret.