(PHP 5 >= 5.5.0, PHP 7)
openssl_pbkdf2 — Generates a PKCS5 v2 PBKDF2 string
$password
, string $salt
, int $key_length
, int $iterations
[, string $digest_algorithm = "sha1"
] )openssl_pbkdf2() computes PBKDF2 (Password-Based Key Derivation Function 2), a key derivation function defined in PKCS5 v2.
passwordPassword from which the derived key is generated.
saltPBKDF2 recommends a crytographic salt of at least 64 bits (8 bytes).
key_lengthLength of desired output key.
iterationsThe number of iterations desired. » NIST recommends at least 10,000.
digest_algorithmOptional hash or digest algorithm from openssl_get_md_methods(). Defaults to SHA-1.
Returns raw binary string 或者在失败时返回 FALSE.
Example #1 openssl_pbkdf2() example
<?php
$password = 'yOuR-pAs5w0rd-hERe';
$salt = openssl_random_pseudo_bytes(12);
$keyLength = 40;
$iterations = 10000;
$generated_key = openssl_pbkdf2($password, $salt, $keyLength, $iterations, 'sha256');
echo bin2hex($generated_key)."\n";
echo base64_encode($generated_key)."\n";
?>
Despite the manual claiming that this is available in PHP 5.5 and above, this function wasn't made available in my local install.
I expect that having a prehistoric OpenSSL library version installed is the likely culprit.
If you're using PHP 5.5 and don't have this function available in your OpenSSL extension, look at the functionally equivalent hash_pbkdf2 function instead.