New abstract class that makes some of the DES key

processing logic shareable across implementations

Author: Rican7

src/Robin/Ntlm/Crypt/Des/AbstractDesEncrypter.php

@@ -0,0 +1,126 @@
+<?php
+/**
+ * Robin NTLM
+ *
+ * @copyright 2015 Robin Powered, Inc.
+ * @link https://robinpowered.com/
+ */
+
+namespace Robin\Ntlm\Crypt\Des;
+
+use SplFixedArray;
+
+/**
+ * {@inheritDoc}
+ *
+ * Provides an abstraction for common NTLM required operations, such as key
+ * expansion and normalization.
+ */
+abstract class AbstractDesEncrypter implements DesEncrypterInterface
+{
+
+    /**
+     * Properties
+     */
+
+    /**
+     * Whether or not to expand and normalize the key before encrypting.
+     *
+     * @type bool
+     */
+    private $expand_and_normalize_keys;
+
+
+    /**
+     * Methods
+     */
+
+    /**
+     * Constructor
+     *
+     * @param bool $expand_and_normalize_keys Whether or not to expand and
+     *   normalize the key before encrypting.
+     */
+    public function __construct($expand_and_normalize_keys = true)
+    {
+        $this->expand_and_normalize_keys = $expand_and_normalize_keys;
+    }
+
+    /**
+     * Process a key for DES encryption.
+     *
+     * Optionally performs an expansion and normalization process to the key.
+     *
+     * @param string $raw_key The raw key.
+     * @return string The processed key.
+     */
+    protected function processKey($raw_key)
+    {
+        $key = $raw_key;
+
+        if ($this->expand_and_normalize_keys) {
+            $key = self::expand56BitKeyTo64BitKey($key, true);
+        }
+
+        return $key;
+    }
+
+    /**
+     * Expands a 56-bit key to a full 64-bit key for DES encryption.
+     *
+     * @link http://php.net/manual/en/ref.hash.php#84587 Implementation basis.
+     * @link https://github.com/jclulow/node-smbhash/blob/edc48e2b/lib/common.js
+     *   Inspired by Joshua Clulow's work.
+     * @param string $string_key The 56-bit key to expand.
+     * @param bool $set_parity Whether or not to set parity for each byte.
+     * @return string The expanded key.
+     */
+    private static function expand56BitKeyTo64BitKey($string_key, $set_parity = true)
+    {
+        $byte_array_56 = new SplFixedArray(7);
+        $byte_array_64 = new SplFixedArray(8);
+        $key_64bit = '';
+
+        // Get the byte value of each ASCII character in the string
+        for ($i = 0; $i < $byte_array_56->getSize(); $i++) {
+            $byte_array_56[$i] = isset($string_key[$i]) ? ord($string_key[$i]) : 0;
+        }
+
+        $byte_array_64[0] = $byte_array_56[0] & 254;
+        $byte_array_64[1] = ($byte_array_56[0] << 7) | ($byte_array_56[1] >> 1);
+        $byte_array_64[2] = ($byte_array_56[1] << 6) | ($byte_array_56[2] >> 2);
+        $byte_array_64[3] = ($byte_array_56[2] << 5) | ($byte_array_56[3] >> 3);
+        $byte_array_64[4] = ($byte_array_56[3] << 4) | ($byte_array_56[4] >> 4);
+        $byte_array_64[5] = ($byte_array_56[4] << 3) | ($byte_array_56[5] >> 5);
+        $byte_array_64[6] = ($byte_array_56[5] << 2) | ($byte_array_56[6] >> 6);
+        $byte_array_64[7] = $byte_array_56[6] << 1;
+
+        foreach ($byte_array_64 as $byte_val) {
+            // Optionally set parity for each byte
+            $byte_val = $set_parity ? self::setParityBit($byte_val) : $byte_val;
+
+            $key_64bit .= chr($byte_val);
+        }
+
+        return $key_64bit;
+    }
+
+    /**
+     * Set an odd parity bit for a given byte, in least-significant position.
+     *
+     * @param int $byte An 8-bit byte value.
+     * @return int An 8-bit byte value.
+     */
+    private static function setParityBit($byte)
+    {
+        $parity = 1;
+
+        for ($i = 1; $i < 8; $i++) {
+            $parity = ($parity + (($byte >> $i) & 1)) %2;
+        }
+
+        $byte = $byte | ($parity & 1);
+
+        return $byte;
+    }
+}