digital certificate (DC)

Definition

Attachment to an email, or encoded data embedded in a webpage, which serves as a guaranty that the parties to a transaction are who they claim to be. It consists of a long string of binary code (which performs the function of a photograph on a passport) issued by a certification authority (CA)—an entity distinct from the sender and the receiver or the buyer and the seller. The CA authenticates the parties' identities and creates a public-key for message coding (encryption), and a private-key for message decoding (decryption). A DC does not imply anything about the transaction itself and, like a passport, expires after a specified period (usually one year). It also contains a certificate number, dates during which it is valid, and CA's name and digital signature.