mcrypt_get_key_size

(PHP 4, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

mcrypt_get_key_size — Gets the key size of the specified cipher

Warning

This function has been DEPRECATED as of PHP 7.1.0 and REMOVED as of PHP 7.2.0. Relying on this function is highly discouraged.

mcrypt_get_key_size(int $cipher): int|false

mcrypt_get_key_size(string $cipher, string $mode): int|false

The first prototype is when linked against libmcrypt 2.2.x, the second when linked against libmcrypt 2.4.x or 2.5.x.

mcrypt_get_key_size() is used to get the size of a key of the specified cipher (in combination with an encryption mode).

It is more useful to use the mcrypt_enc_get_key_size() function as this uses the resource returned by mcrypt_module_open().

cipher: One of the MCRYPT_ciphername constants, or the name of the algorithm as string.
mode: One of the MCRYPT_MODE_modename constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".

Returns the maximum supported key size of the algorithm in bytes or false on failure.

Example #1 mcrypt_get_key_size() Example

<?php
    echo mcrypt_get_key_size('tripledes', 'ecb');
?>

The example above shows how to use this function when linked against libmcrypt 2.4.x or 2.5.x.

The above example will output:

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Robin ¶

14 years ago


While not specified in the description, this function, just like mcrypt_enc_get_key_size(), returns the cipher's largest key size in BYTES.