Passphrase¶
A passphrase is a longer and more critical password. It may be build by combining several words, hence building a phrase.
Because a passphrase is typically longer than a conventional password, often four or more randomly chosen words following the Diceware method, it carries substantially more entropy while remaining easier for a human to memorize and type than an equivalent-strength string of random characters and symbols.
Passphrases used as passwords are hashed and verified like any other password with password_hash()/password_verify(), using the bcrypt or Argon2 algorithms. They are also common as input to key-derivation functions: sodium_crypto_pwhash() in the sodium extension derives a fixed-length encryption or signing key from a passphrase and a salt, and OpenSSL private keys are frequently protected with a passphrase supplied to openssl_pkey_export() or the openssl command-line tool.
See also Generate Secure, Memorable Passphrases in PHP with PHP Passphrase.
Related : Password API, Password, Secure Sockets Layer (SSL), Word Combination