mcrypt_get_iv_size(3) [php man page]

MCRYPT_GET_IV_SIZE(3)							 1						     MCRYPT_GET_IV_SIZE(3)

mcrypt_get_iv_size - Returns the size of the IV belonging to a specific cipher/mode combination

SYNOPSIS

       int mcrypt_get_iv_size (string  $cipher, string	$mode)

DESCRIPTION

	Gets the size of the IV belonging to a specific $cipher/$mode combination.

	It is more useful to use the mcrypt_enc_get_iv_size(3) function as this uses the resource returned by mcrypt_module_open(3).

PARAMETERS

	      o $cipher
		-One of the MCRYPT_ciphername constants, or the name of the algorithm as string.

	      o $mode
		-One  of  the MCRYPT_MODE_modename constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream". The
		IV is ignored in ECB mode as this mode does not require it. You will need to have the same IV  (think:	starting  point)  both	at
		encryption and decryption stages, otherwise your encryption will fail.

RETURN VALUES

	Returns  the  size  of the Initialization Vector (IV) in bytes. On error the function returns FALSE. If the IV is ignored in the specified
       cipher/mode combination zero is returned.

EXAMPLES

       Example #1

	      mcrypt_get_iv_size(3) Example

	      <?php
		  echo mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB) . "
";

		  echo mcrypt_get_iv_size('des', 'ecb') . "
";
	      ?>

SEE ALSO

       mcrypt_get_block_size(3), mcrypt_enc_get_iv_size(3), mcrypt_create_iv(3).

PHP Documentation Group 												     MCRYPT_GET_IV_SIZE(3)

MCRYPT_DECRYPT(3)							 1							 MCRYPT_DECRYPT(3)

mcrypt_decrypt - Decrypts crypttext with given parameters

SYNOPSIS

       string mcrypt_decrypt (string  $cipher, string  $key, string  $data, string  $mode, [string  $iv])

DESCRIPTION

	Decrypts the $data and returns the unencrypted data.

PARAMETERS

	      o $cipher
		-One of the MCRYPT_ciphername constants, or the name of the algorithm as string.

	      o $key
		-  The	key  with  which the data was encrypted. If the provided key size is not supported by the cipher, the function will emit a
		warning and return FALSE

	      o $data
		- The data that will be decrypted with the given $cipher and $mode. If the size of the data is not n * blocksize, the data will be
		padded with ' '.

	      o $mode
		-One of the MCRYPT_MODE_modename constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".

	      o $iv
		-Used  for  the  initialization in CBC, CFB, OFB modes, and in some algorithms in STREAM mode. If the provided IV size is not sup-
		ported by the chaining mode or no IV was provided, but the chaining mode requires one, the function will emit a warning and return
		FALSE.

RETURN VALUES

	Returns the decrypted data as a string or FALSE on failure.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.6.0	|						    |
       |	|						    |
       |	|  Invalid   $key  and	$iv  sizes  are  no  longer |
       |	| accepted.  mcrypt_decrypt(3)	will  now  throw  a |
       |	| warning  and	return	FALSE  if  the	inputs	are |
       |	| invalid. Previously keys and IVs were padded with |
       |	| ' ' bytes to the next valid size.		    |
       |	|						    |
       +--------+---------------------------------------------------+
SEE ALSO

       mcrypt_encrypt(3).

PHP Documentation Group 													 MCRYPT_DECRYPT(3)