php man page for openssl_cipher_iv_length

OPENSSL_CIPHER_IV_LENGTH(3)						 1					       OPENSSL_CIPHER_IV_LENGTH(3)

openssl_cipher_iv_length - Gets the cipher iv length

SYNOPSIS
       int openssl_cipher_iv_length (string  $method)

DESCRIPTION
	Gets the cipher initialization vector (iv) length.

PARAMETERS
	      o $method
		- The cipher method, see openssl_get_cipher_methods(3) for a list of potential values.

RETURN VALUES
	Returns the cipher length on success, or FALSE on failure.

ERRORS
/EXCEPTIONS
	Emits an E_WARNING level error when the cipher algorithm is unknown.

EXAMPLES
       Example #1

	      openssl_cipher_iv_length(3) example

	      <?php
	      $method = 'AES-128-CBC';
	      $ivlen = openssl_cipher_iv_length($method);

	      echo $ivlen;
	      ?>

	      The above example will output something similar to:

	      16

PHP Documentation Group 											       OPENSSL_CIPHER_IV_LENGTH(3)