Microsoft® Windows® 2000 Security Handbook

Digital Signatures

One topic I should discuss briefly, just because it is one of the hot topics surrounding public-key cryptography and PKI, is digital signatures. A digital signature combines a user's private key with the data to be signed so that the following occur:

• Only someone possessing the private key could have created the digital signature.

• Anyone can verify the digital signature by accessing the user's corresponding public key.

• Any modification of the signed data invalidates the digital signature, ensuring data (and digital signature) integrity.

Essentially, digital signatures have the potential of becoming as much a way to sign an agreement as your handwritten signature is today. In fact, some states consider digital signatures legally ...