Publication Information
S. R. Tate and R. R. Panko. Digital Signatures and Electronic Signatures, in The Handbook of Technology Management, Hossein Bidgoli, ed., John Wiley & Sons, 2009. Security&CryptographyBook Chapter
Abstract
When we send letters, we sign them to indicate that they are from us. When we sign contracts, we are expressing our willingness to abide by the terms of the contract. We cannot later repudiate the contract because our signature binds us. Signing is also possible in the electronic world, and it generally serves the same purposes.
There are three related terms we use in this article. An electronic signature (e-signature) is any signing method that is used with computers and networks. It is the broadest concept. It includes such things as clicking a button to indicate that we accept the terms of a program’s end-user licensing agreement.
The other two terms refer to methods for making electronic signatures—specifically, for adding signature blocks to outgoing messages. Digital signatures are signature blocks created with techniques from public key cryptography. Message authentication codes (MACs) also are per-message signature blocks, but they are created using symmetric key cryptographic techniques. MACs are also called keyed hash functions.
In our discussion, we begin with the most familiar technology, digital signatures. We then discuss MACs and, finally, electronic signatures broadly.