What is passphrase? - Definition from Whatis.com

A passphrase is a string of characters longer than the usual password (which is typically from four to 16 characters long) that is used in creating a digital signature (an encoded signature that proves to someone that it was really you who sent a message) or in an encryption or a decryption of a message. For example, Phil Zimmermann's popular encryption program, Pretty Good Privacy, requires a passphrase when you sign or decrypt a message. Passphrases are often up to 100 characters in length.

Contributor(s): Arnold Reinhold
This was last updated in September 1999

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