passphrase definition operating system
A string of words and characters that you type in to authenticate yourself. Passphrases differ from passwords only in length. Passwords are usually short - six to ten characters. Passphrases are usually much longer - up to 100 characters or more. Their greater length makes passphrases more secure. Modern passphrases were invented by Sigmund N. Porter in 1982.
Phil Zimmermann's popular encryption program PGP
, for example, requires you to make up a passphrase that you then must enter whenever you sign or decrypt messages.