PHP: mcrypt_generic_init - Manual

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mcrypt_generic mcrypt_generic_end

Last updated: Fri, 26 Jan 2007

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# mcrypt_generic_init

(PHP 4 >= 4.0.2, PHP 5)

mcrypt_generic_init -- This function initializes all buffers needed for encryption

## Description

int mcrypt_generic_init ( resource td, string key, string iv )

The maximum length of the key should be the one obtained by calling mcrypt_enc_get_key_size() and every value smaller than this is legal. The IV should normally have the size of the algorithms block size, but you must obtain the size by calling mcrypt_enc_get_iv_size(). IV is ignored in ECB. IV MUST exist in CFB, CBC, STREAM, nOFB and OFB modes. It needs to be random and unique (but not secret). The same IV must be used for encryption/decryption. If you do not want to use it you should set it to zeros, but this is not recommended.

The function returns a negative value on error, -3 when the key length was incorrect, -4 when there was a memory allocation problem and any other return value is an unknown error. If an error occurs a warning will be displayed accordingly. `FALSE` is returned if incorrect parameters were passed.

You need to call this function before every call to mcrypt_generic() or mdecrypt_generic().

See for an example mcrypt_module_open().

add a note User Contributed Notes
mcrypt_generic_init
cnww
25-Aug-2006 02:14
`If you write error-checking into your code, be warned that this function returns FALSE on some errors, and 0 on success, hence
mcrypt_generic_init( $a, $b, $c ) or die( "Oops");
ALWAYS exits with the error message "Oops", and
(mcrypt_generic_init( $a, $b, $c ) >= 0 ) or die( "Oops");
Sometimes continues when mcrypt_generic_init() actually failed.
To check for successful init use something like:
$s = mcrypt_generic_init( $a, $b, $c );
if( ($s < 0) || ($s === false))
die( "Really an error" );`
add a note
mcrypt_generic mcrypt_generic_end

Last updated: Fri, 26 Jan 2007
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