openssl_pbkdf2

    (PHP 5 >= 5.5.0, PHP 7, PHP 8)

    openssl_pbkdf2 — Generates a PKCS5 v2 PBKDF2 string

    Description

    openssl_pbkdf2(
        string$password,
        string$salt,
        int$key_length,
        int$iterations,
        string$digest_algo = "sha1"
    ): string|false

    openssl_pbkdf2() computes PBKDF2 (Password-Based Key Derivation Function 2), a key derivation function defined in PKCS5 v2.

    Parameters

    password

    Password from which the derived key is generated.

    salt

    PBKDF2 recommends a crytographic salt of at least 64 bits (8 bytes).

    key_length

    Length of desired output key.

    iterations

    The number of iterations desired. » NIST recommends at least 10,000.

    digest_algo

    Optional hash or digest algorithm from openssl_get_md_methods(). Defaults to SHA-1.

    Return Values

    Returns raw binary string or false on failure.

    Examples

    Example #1 openssl_pbkdf2() example

    <?php
    $password     = 'password';
    $salt = openssl_random_pseudo_bytes(16);
    $keyLength = 20;
    $iterations = 600000;
    $generated_key = openssl_pbkdf2($password, $salt, $keyLength, $iterations, 'sha256');
    echo     bin2hex($generated_key)."\n";
    echo     base64_encode($generated_key)."\n";
    ?>

    See Also

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