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mcrypt_get_key_size

(PHP 4, PHP 5)

mcrypt_get_key_sizeGets the key size of the specified cipher

Description

int mcrypt_get_key_size ( int $cipher )
int mcrypt_get_key_size ( string $cipher , string $mode )

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().

Parameters

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".

Return Values

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

Examples

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:

24

See Also

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User Contributed Notes 1 note

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Robin
4 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.
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