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Digital Signatures: A Tutorial Survey Disclosure Number: IPCOM000131589D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Nov-11
Document File: 13 page(s) / 45K

Publishing Venue

Software Patent Institute

Related People

Selim G. Akl: AUTHOR [+3]


Queen's University, Ontario, Canada

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Digital Signatures: A Tutorial Survey

Selim G. Akl,

Queen's University, Ontario, Canada

As paper gives way to electronic mail, a secure means for validating and authenticating messages is required. The answer could be one of several digital signature schemes.

Recent advances in telecommunications and computer networking have brought us into the era of electronic mail. By providing rapid and economic channels for the dissemination of data, electronic mail systems are certain to significantly reduce our reliance on paper as the major medium for transactions. It is also clear that with the widespread implementation and use of such systems, senders and receivers of sensitive or valuable information will require secure means for validating and authenticating the electronic messages they exchange. Validation and authentication refer to the methods of certifying the contents of a message and its originator, respectively. Both functions can usually be achieved through the use of a digital signature, which is appended to (or an integral part of) every message. Because a digital signature is just a string of 0's and 1's, it differs from an analog signature (a line drawn with pen on paper) in two important ways:

(1) No matter how complicated an analog signature is, a forger intent on committing fraud will eventually be able to duplicate it. A digital signature, on the other hand, should by definition be inimitable.

(2) A person's analog signature is constant; it is the same on all documents signed by that person. By contrast, digital signatures must be different for every message.

From this it follows that a digital signature is a message-dependent quantity that can be computed only by the sender of the message on the basis of some private information. It allows authentication of messages by guaranteeing that no one can forge the sender's signature and the sender cannot deny a message he sent. In addition, validation is also possible because the receiver can verify that no one tampered with the message while it was on its way to him and because the sender is sure that the receiver will not be able to change even one bit of the message without altering the signature. It is therefore clear that for parties with conflicting interests, a digital signature should offer more protection against fraud than today's analog signature.

Digital signature schemes are usually classified into one of two categories: truesignaturesor arbitrated signatures. In a true signature scheme, signed messages produced by the sender S are transmitted...