HTTP: The Definitive Guide

Digital Certificates

In this section, we talk about digital certificates, the “ID cards” of the Internet. Digital certificates (often called “certs,” like the breath mints) contain information about a user or firm that has been vouched for by a trusted organization.

We all carry many forms of identification. Some IDs, such as passports and drivers’ licenses, are trusted enough to prove one’s identity in many situations. For example, a U.S. driver’s license is sufficient proof of identity to let you board an airplane to New York for New Year’s Eve, and it’s sufficient proof of your age to let you drink intoxicating beverages with your friends when you get there.

More trusted forms of identification, such as passports, are signed and stamped by a government on special paper. They are harder to forge, so they inherently carry a higher level of trust. Some corporate badges and smart cards include electronics to help strengthen the identity of the carrier. Some top-secret government organizations even need to match up your fingerprints or retinal capillary patterns with your ID before trusting it!

Other forms of ID, such as business cards, are relatively easy to forge, so people trust this information less. They may be fine for professional interactions but probably are not enough proof of employment when you apply for a home loan.

The Guts of a Certificate

Digital certificates also contain a set of information, all of which is digitally signed by an official “certificate authority.” ...