--- /dev/null
+<?php
+/**
+ * A packing mode implementation for ASNIx923 padding
+ *
+ * PHP version 5.3
+ *
+ * @category PHPCryptLib
+ * @package Encryption
+ * @subpackage PackingMode
+ * @author Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @copyright 2011 The Authors
+ * @license http://www.opensource.org/licenses/mit-license.html MIT License
+ * @version Build @@version@@
+ */
+
+namespace CryptLib\Encryption\PackingMode;
+
+/**
+ * A packing mode implementation for ASNIx923 padding
+ *
+ * @category PHPCryptLib
+ * @package Encryption
+ * @subpackage PackingMode
+ * @author Anthony Ferrara <ircmaxell@ircmaxell.com>
+ */
+class ANSIx923 implements \CryptLib\Encryption\PackingMode {
+
+ /**
+ * Pad the string to the specified size
+ *
+ * @param string $string The string to pad
+ * @param int $blockSize The size to pad to
+ *
+ * @return string The padded string
+ */
+ public function pad($string, $blockSize = 32) {
+ $pad = $blockSize - (strlen($string) % $blockSize);
+ return $string . str_repeat(chr(0), $pad - 1) . chr($pad);
+ }
+
+ /**
+ * Strip the padding from the supplied string
+ *
+ * @param string $string The string to trim
+ *
+ * @return string The unpadded string
+ */
+ public function strip($string) {
+ $end = ord(substr($string, -1));
+ $len = strlen($string) - $end;
+ $tmp = str_repeat(chr(0), $end - 1) . chr($end);
+ if (substr($string, $len) == $tmp) {
+ return substr($string, 0, $len);
+ }
+ return false;
+ }
+
+}