digital certificate

An encrypted and digitally signed attachment that authenticates a user on the Internet or an intranet.A digital certificate is issued by a certificate authority (CA), and attests to the legitimacy of an online transfer of information, funds, or other sensitive materials through the use of encryption. A digital certificate includes the sender's name, a serial number, expiration dates, a copy of the certificate holder's public key, and the digital signature of the issuing CA. A digital certificate holder has both a private key and a public key. The private key is held only by the user and is for signing outgoing messages and decrypting incoming messages. The public key is available to anyone for encrypting data to send to the holder of that public key, who then uses the private key to decrypt the message. Many digital certificates conform to the X.509 standard. See also authentication, CA, encryption, Internet, intranet, PKI, private key encryption, public key encryption, and X.509.