digital signatures

APPLICATIONS SUCH AS banking, stock trading, and the sale and purchase of merchandise are increasingly emphasizing electronic transactions to minimize operational costs and provide enhanced services. This has led to phenomenal increas-

ments. Validation refers to the process of certifying the contents of the document, while authentication refers to the process of certifying the sender of the document.
In this article, the terms document and message are used interchangeably.

Digital signatures
S.R. SUBRAMANYA AND BYUNG K. YI

use some information that is unique to the sender to prevent both forgery and denial; it must be relatively easy to produce; it must be relatively easy to recognize and verify the authenticity of digital signature; it must be computationally infeasible to forge a digital signature either by constructing a new message for an existing digital signature or constructing a fraudulent digital signature for a given message; and it must be practical to retcopies of the digital signatures in storage for arbitrating possible disputes later.
To verify that the received document is indeed from the claimed sender and that the contents have not been altered, several procedures, called authentication techniques, have been developed.
However, message authentication techniques cannot be directly used as digital signatures due to inadequacies of authentication techniques. For example, although message authentication protects the two parties exchanging messages from a third party, it does not protect the two parties against each other. In addition, elementary authentication schemes produce signatures that are as long as the message themselves.

Basic notions and terminology
© DIGITALVISION, STOCKBYTE, COMSTOCK

es in the amounts of electronic documents that are generated, processed, and stored in computers and transmitted over networks. This electronic information handled in these applications is valuable and
sensitive