<?php
namespace Kant\Secure\Crypt;

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * Pure-PHP implementations of keyed-hash message authentication codes (HMACs) and various cryptographic hashing functions.
 *
 * Uses hash() or mhash() if available and an internal implementation, otherwise. Currently supports the following:
 *
 * md2, md5, md5-96, sha1, sha1-96, sha256, sha384, and sha512
 *
 * If {@link Crypt_Hash::setKey() setKey()} is called, {@link Crypt_Hash::hash() hash()} will return the HMAC as opposed to
 * the hash. If no valid algorithm is provided, sha1 will be used.
 *
 * PHP versions 4 and 5
 *
 * {@internal The variable names are the same as those in
 * {@link http://tools.ietf.org/html/rfc2104#section-2 RFC2104}.}}
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 * include('Crypt/Hash.php');
 *
 * $hash = new Crypt_Hash('sha1');
 *
 * $hash->setKey('abcdefg');
 *
 * echo base64_encode($hash->hash('abcdefg'));
 * ?>
 * </code>
 *
 * LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @category Crypt
 * @package Crypt_Hash
 * @author Jim Wigginton <terrafrost@php.net>
 * @copyright MMVII Jim Wigginton
 * @license http://www.opensource.org/licenses/mit-license.html MIT License
 * @version $Id: Hash.php,v 1.6 2009/11/23 23:37:07 terrafrost Exp $
 * @link http://phpseclib.sourceforge.net
 */
/*
 * #@+
 * @access private
 * @see Crypt_Hash::Crypt_Hash()
 */
/**
 * Toggles the internal implementation
 */
define('CRYPT_HASH_MODE_INTERNAL', 1);
/**
 * Toggles the mhash() implementation, which has been deprecated on PHP 5.3.0+.
 */
define('CRYPT_HASH_MODE_MHASH', 2);
/**
 * Toggles the hash() implementation, which works on PHP 5.1.2+.
 */
define('CRYPT_HASH_MODE_HASH', 3);

/* * #@- */

/**
 * Pure-PHP implementations of keyed-hash message authentication codes (HMACs) and various cryptographic hashing functions.
 *
 * @author Jim Wigginton <terrafrost@php.net>
 * @version 0.1.0
 * @access public
 * @package Crypt_Hash
 */
class Crypt_Hash
{

    /**
     * Byte-length of compression blocks / key (Internal HMAC)
     *
     * @see Crypt_Hash::setAlgorithm()
     * @var Integer
     * @access private
     */
    var $b;

    /**
     * Byte-length of hash output (Internal HMAC)
     *
     * @see Crypt_Hash::setHash()
     * @var Integer
     * @access private
     */
    var $l = false;

    /**
     * Hash Algorithm
     *
     * @see Crypt_Hash::setHash()
     * @var String
     * @access private
     */
    var $hash;

    /**
     * Key
     *
     * @see Crypt_Hash::setKey()
     * @var String
     * @access private
     */
    var $key = false;

    /**
     * Outer XOR (Internal HMAC)
     *
     * @see Crypt_Hash::setKey()
     * @var String
     * @access private
     */
    var $opad;

    /**
     * Inner XOR (Internal HMAC)
     *
     * @see Crypt_Hash::setKey()
     * @var String
     * @access private
     */
    var $ipad;

    /**
     * Default Constructor.
     *
     * @param
     *            optional String $hash
     * @return Crypt_Hash
     * @access public
     */
    function __construct($hash = 'sha1')
    {
        if (!defined('CRYPT_HASH_MODE')) {
            switch (true) {
                case extension_loaded('hash'):
                    define('CRYPT_HASH_MODE', CRYPT_HASH_MODE_HASH);
                    break;
                case extension_loaded('mhash'):
                    define('CRYPT_HASH_MODE', CRYPT_HASH_MODE_MHASH);
                    break;
                default:
                    define('CRYPT_HASH_MODE', CRYPT_HASH_MODE_INTERNAL);
            }
        }
        
        $this->setHash($hash);
    }

    /**
     * Sets the key for HMACs
     *
     * Keys can be of any length.
     *
     * @access public
     * @param
     *            optional String $key
     */
    function setKey($key = false)
    {
        $this->key = $key;
    }

    /**
     * Sets the hash function.
     *
     * @access public
     * @param String $hash            
     */
    function setHash($hash)
    {
        $hash = strtolower($hash);
        switch ($hash) {
            case 'md5-96':
            case 'sha1-96':
                $this->l = 12; // 96 / 8 = 12
                break;
            case 'md2':
            case 'md5':
                $this->l = 16;
                break;
            case 'sha1':
                $this->l = 20;
                break;
            case 'sha256':
                $this->l = 32;
                break;
            case 'sha384':
                $this->l = 48;
                break;
            case 'sha512':
                $this->l = 64;
        }
        
        switch ($hash) {
            case 'md2':
                $mode = CRYPT_HASH_MODE == CRYPT_HASH_MODE_HASH && in_array('md2', hash_algos()) ? CRYPT_HASH_MODE_HASH : CRYPT_HASH_MODE_INTERNAL;
                break;
            case 'sha384':
            case 'sha512':
                $mode = CRYPT_HASH_MODE == CRYPT_HASH_MODE_MHASH ? CRYPT_HASH_MODE_INTERNAL : CRYPT_HASH_MODE;
                break;
            default:
                $mode = CRYPT_HASH_MODE;
        }
        
        switch ($mode) {
            case CRYPT_HASH_MODE_MHASH:
                switch ($hash) {
                    case 'md5':
                    case 'md5-96':
                        $this->hash = MHASH_MD5;
                        break;
                    case 'sha256':
                        $this->hash = MHASH_SHA256;
                        break;
                    case 'sha1':
                    case 'sha1-96':
                    default:
                        $this->hash = MHASH_SHA1;
                }
                return;
            case CRYPT_HASH_MODE_HASH:
                switch ($hash) {
                    case 'md5':
                    case 'md5-96':
                        $this->hash = 'md5';
                        return;
                    case 'md2':
                    case 'sha256':
                    case 'sha384':
                    case 'sha512':
                        $this->hash = $hash;
                        return;
                    case 'sha1':
                    case 'sha1-96':
                    default:
                        $this->hash = 'sha1';
                }
                return;
        }
        
        switch ($hash) {
            case 'md2':
                $this->b = 16;
                $this->hash = array(
                    $this,
                    '_md2'
                );
                break;
            case 'md5':
            case 'md5-96':
                $this->b = 64;
                $this->hash = array(
                    $this,
                    '_md5'
                );
                break;
            case 'sha256':
                $this->b = 64;
                $this->hash = array(
                    $this,
                    '_sha256'
                );
                break;
            case 'sha384':
            case 'sha512':
                $this->b = 128;
                $this->hash = array(
                    $this,
                    '_sha512'
                );
                break;
            case 'sha1':
            case 'sha1-96':
            default:
                $this->b = 64;
                $this->hash = array(
                    $this,
                    '_sha1'
                );
        }
        
        $this->ipad = str_repeat(chr(0x36), $this->b);
        $this->opad = str_repeat(chr(0x5C), $this->b);
    }

    /**
     * Compute the HMAC.
     *
     * @access public
     * @param String $text            
     * @return String
     */
    function hash($text)
    {
        $mode = is_array($this->hash) ? CRYPT_HASH_MODE_INTERNAL : CRYPT_HASH_MODE;
        
        if (!empty($this->key) || is_string($this->key)) {
            switch ($mode) {
                case CRYPT_HASH_MODE_MHASH:
                    $output = mhash($this->hash, $text, $this->key);
                    break;
                case CRYPT_HASH_MODE_HASH:
                    $output = hash_hmac($this->hash, $text, $this->key, true);
                    break;
                case CRYPT_HASH_MODE_INTERNAL:
                    /* "Applications that use keys longer than B bytes will first hash the key using H and then use the
                      resultant L byte string as the actual key to HMAC."

                      -- http://tools.ietf.org/html/rfc2104#section-2 */
                    $key = strlen($this->key) > $this->b ? call_user_func($this->hash, $this->key) : $this->key;
                    
                    $key = str_pad($key, $this->b, chr(0)); // step 1
                    $temp = $this->ipad ^ $key; // step 2
                    $temp .= $text; // step 3
                    $temp = call_user_func($this->hash, $temp); // step 4
                    $output = $this->opad ^ $key; // step 5
                    $output .= $temp; // step 6
                    $output = call_user_func($this->hash, $output); // step 7
            }
        } else {
            switch ($mode) {
                case CRYPT_HASH_MODE_MHASH:
                    $output = mhash($this->hash, $text);
                    break;
                case CRYPT_HASH_MODE_HASH:
                    $output = hash($this->hash, $text, true);
                    break;
                case CRYPT_HASH_MODE_INTERNAL:
                    $output = call_user_func($this->hash, $text);
            }
        }
        
        return substr($output, 0, $this->l);
    }

    /**
     * Returns the hash length (in bytes)
     *
     * @access public
     * @return Integer
     */
    function getLength()
    {
        return $this->l;
    }

    /**
     * Wrapper for MD5
     *
     * @access private
     * @param String $m            
     */
    function _md5($m)
    {
        return pack('H*', md5($m));
    }

    /**
     * Wrapper for SHA1
     *
     * @access private
     * @param String $m            
     */
    function _sha1($m)
    {
        return pack('H*', sha1($m));
    }

    /**
     * Pure-PHP implementation of MD2
     *
     * See {@link http://tools.ietf.org/html/rfc1319 RFC1319}.
     *
     * @access private
     * @param String $m            
     */
    function _md2($m)
    {
        static $s = array(
            41,
            46,
            67,
            201,
            162,
            216,
            124,
            1,
            61,
            54,
            84,
            161,
            236,
            240,
            6,
            19,
            98,
            167,
            5,
            243,
            192,
            199,
            115,
            140,
            152,
            147,
            43,
            217,
            188,
            76,
            130,
            202,
            30,
            155,
            87,
            60,
            253,
            212,
            224,
            22,
            103,
            66,
            111,
            24,
            138,
            23,
            229,
            18,
            190,
            78,
            196,
            214,
            218,
            158,
            222,
            73,
            160,
            251,
            245,
            142,
            187,
            47,
            238,
            122,
            169,
            104,
            121,
            145,
            21,
            178,
            7,
            63,
            148,
            194,
            16,
            137,
            11,
            34,
            95,
            33,
            128,
            127,
            93,
            154,
            90,
            144,
            50,
            39,
            53,
            62,
            204,
            231,
            191,
            247,
            151,
            3,
            255,
            25,
            48,
            179,
            72,
            165,
            181,
            209,
            215,
            94,
            146,
            42,
            172,
            86,
            170,
            198,
            79,
            184,
            56,
            210,
            150,
            164,
            125,
            182,
            118,
            252,
            107,
            226,
            156,
            116,
            4,
            241,
            69,
            157,
            112,
            89,
            100,
            113,
            135,
            32,
            134,
            91,
            207,
            101,
            230,
            45,
            168,
            2,
            27,
            96,
            37,
            173,
            174,
            176,
            185,
            246,
            28,
            70,
            97,
            105,
            52,
            64,
            126,
            15,
            85,
            71,
            163,
            35,
            221,
            81,
            175,
            58,
            195,
            92,
            249,
            206,
            186,
            197,
            234,
            38,
            44,
            83,
            13,
            110,
            133,
            40,
            132,
            9,
            211,
            223,
            205,
            244,
            65,
            129,
            77,
            82,
            106,
            220,
            55,
            200,
            108,
            193,
            171,
            250,
            36,
            225,
            123,
            8,
            12,
            189,
            177,
            74,
            120,
            136,
            149,
            139,
            227,
            99,
            232,
            109,
            233,
            203,
            213,
            254,
            59,
            0,
            29,
            57,
            242,
            239,
            183,
            14,
            102,
            88,
            208,
            228,
            166,
            119,
            114,
            248,
            235,
            117,
            75,
            10,
            49,
            68,
            80,
            180,
            143,
            237,
            31,
            26,
            219,
            153,
            141,
            51,
            159,
            17,
            131,
            20
        );
        
        // Step 1. Append Padding Bytes
        $pad = 16 - (strlen($m) & 0xF);
        $m .= str_repeat(chr($pad), $pad);
        
        $length = strlen($m);
        
        // Step 2. Append Checksum
        $c = str_repeat(chr(0), 16);
        $l = chr(0);
        for ($i = 0; $i < $length; $i += 16) {
            for ($j = 0; $j < 16; $j ++) {
                // RFC1319 incorrectly states that C[j] should be set to S[c xor L]
                // $c[$j] = chr($s[ord($m[$i + $j] ^ $l)]);
                // per <http://www.rfc-editor.org/errata_search.php?rfc=1319>, however, C[j] should be set to S[c xor L] xor C[j]
                $c[$j] = chr($s[ord($m[$i + $j] ^ $l)] ^ ord($c[$j]));
                $l = $c[$j];
            }
        }
        $m .= $c;
        
        $length += 16;
        
        // Step 3. Initialize MD Buffer
        $x = str_repeat(chr(0), 48);
        
        // Step 4. Process Message in 16-Byte Blocks
        for ($i = 0; $i < $length; $i += 16) {
            for ($j = 0; $j < 16; $j ++) {
                $x[$j + 16] = $m[$i + $j];
                $x[$j + 32] = $x[$j + 16] ^ $x[$j];
            }
            $t = chr(0);
            for ($j = 0; $j < 18; $j ++) {
                for ($k = 0; $k < 48; $k ++) {
                    $x[$k] = $t = $x[$k] ^ chr($s[ord($t)]);
                    // $t = $x[$k] = $x[$k] ^ chr($s[ord($t)]);
                }
                $t = chr(ord($t) + $j);
            }
        }
        
        // Step 5. Output
        return substr($x, 0, 16);
    }

    /**
     * Pure-PHP implementation of SHA256
     *
     * See {@link http://en.wikipedia.org/wiki/SHA_hash_functions#SHA-256_.28a_SHA-2_variant.29_pseudocode SHA-256 (a SHA-2 variant) pseudocode - Wikipedia}.
     *
     * @access private
     * @param String $m            
     */
    function _sha256($m)
    {
        if (extension_loaded('suhosin')) {
            return pack('H*', sha256($m));
        }
        
        // Initialize variables
        $hash = array(
            0x6a09e667,
            0xbb67ae85,
            0x3c6ef372,
            0xa54ff53a,
            0x510e527f,
            0x9b05688c,
            0x1f83d9ab,
            0x5be0cd19
        );
        // Initialize table of round constants
        // (first 32 bits of the fractional parts of the cube roots of the first 64 primes 2..311)
        static $k = array(
            0x428a2f98,
            0x71374491,
            0xb5c0fbcf,
            0xe9b5dba5,
            0x3956c25b,
            0x59f111f1,
            0x923f82a4,
            0xab1c5ed5,
            0xd807aa98,
            0x12835b01,
            0x243185be,
            0x550c7dc3,
            0x72be5d74,
            0x80deb1fe,
            0x9bdc06a7,
            0xc19bf174,
            0xe49b69c1,
            0xefbe4786,
            0x0fc19dc6,
            0x240ca1cc,
            0x2de92c6f,
            0x4a7484aa,
            0x5cb0a9dc,
            0x76f988da,
            0x983e5152,
            0xa831c66d,
            0xb00327c8,
            0xbf597fc7,
            0xc6e00bf3,
            0xd5a79147,
            0x06ca6351,
            0x14292967,
            0x27b70a85,
            0x2e1b2138,
            0x4d2c6dfc,
            0x53380d13,
            0x650a7354,
            0x766a0abb,
            0x81c2c92e,
            0x92722c85,
            0xa2bfe8a1,
            0xa81a664b,
            0xc24b8b70,
            0xc76c51a3,
            0xd192e819,
            0xd6990624,
            0xf40e3585,
            0x106aa070,
            0x19a4c116,
            0x1e376c08,
            0x2748774c,
            0x34b0bcb5,
            0x391c0cb3,
            0x4ed8aa4a,
            0x5b9cca4f,
            0x682e6ff3,
            0x748f82ee,
            0x78a5636f,
            0x84c87814,
            0x8cc70208,
            0x90befffa,
            0xa4506ceb,
            0xbef9a3f7,
            0xc67178f2
        );
        
        // Pre-processing
        $length = strlen($m);
        // to round to nearest 56 mod 64, we'll add 64 - (length + (64 - 56)) % 64
        $m .= str_repeat(chr(0), 64 - (($length + 8) & 0x3F));
        $m[$length] = chr(0x80);
        // we don't support hashing strings 512MB long
        $m .= pack('N2', 0, $length << 3);
        
        // Process the message in successive 512-bit chunks
        $chunks = str_split($m, 64);
        foreach ($chunks as $chunk) {
            $w = array();
            for ($i = 0; $i < 16; $i ++) {
                extract(unpack('Ntemp', $this->_string_shift($chunk, 4)));
                $w[] = $temp;
            }
            
            // Extend the sixteen 32-bit words into sixty-four 32-bit words
            for ($i = 16; $i < 64; $i ++) {
                $s0 = $this->_rightRotate($w[$i - 15], 7) ^ $this->_rightRotate($w[$i - 15], 18) ^ $this->_rightShift($w[$i - 15], 3);
                $s1 = $this->_rightRotate($w[$i - 2], 17) ^ $this->_rightRotate($w[$i - 2], 19) ^ $this->_rightShift($w[$i - 2], 10);
                $w[$i] = $this->_add($w[$i - 16], $s0, $w[$i - 7], $s1);
            }
            
            // Initialize hash value for this chunk
            list ($a, $b, $c, $d, $e, $f, $g, $h) = $hash;
            
            // Main loop
            for ($i = 0; $i < 64; $i ++) {
                $s0 = $this->_rightRotate($a, 2) ^ $this->_rightRotate($a, 13) ^ $this->_rightRotate($a, 22);
                $maj = ($a & $b) ^ ($a & $c) ^ ($b & $c);
                $t2 = $this->_add($s0, $maj);
                
                $s1 = $this->_rightRotate($e, 6) ^ $this->_rightRotate($e, 11) ^ $this->_rightRotate($e, 25);
                $ch = ($e & $f) ^ ($this->_not($e) & $g);
                $t1 = $this->_add($h, $s1, $ch, $k[$i], $w[$i]);
                
                $h = $g;
                $g = $f;
                $f = $e;
                $e = $this->_add($d, $t1);
                $d = $c;
                $c = $b;
                $b = $a;
                $a = $this->_add($t1, $t2);
            }
            
            // Add this chunk's hash to result so far
            $hash = array(
                $this->_add($hash[0], $a),
                $this->_add($hash[1], $b),
                $this->_add($hash[2], $c),
                $this->_add($hash[3], $d),
                $this->_add($hash[4], $e),
                $this->_add($hash[5], $f),
                $this->_add($hash[6], $g),
                $this->_add($hash[7], $h)
            );
        }
        
        // Produce the final hash value (big-endian)
        return pack('N8', $hash[0], $hash[1], $hash[2], $hash[3], $hash[4], $hash[5], $hash[6], $hash[7]);
    }

    /**
     * Pure-PHP implementation of SHA384 and SHA512
     *
     * @access private
     * @param String $m            
     */
    function _sha512($m)
    {
        if (!class_exists('Math_BigInteger')) {
            require_once ('Math/BigInteger.php');
        }
        
        static $init384, $init512, $k;
        
        if (!isset($k)) {
            // Initialize variables
            $init384 = array( // initial values for SHA384
                'cbbb9d5dc1059ed8',
                '629a292a367cd507',
                '9159015a3070dd17',
                '152fecd8f70e5939',
                '67332667ffc00b31',
                '8eb44a8768581511',
                'db0c2e0d64f98fa7',
                '47b5481dbefa4fa4'
            );
            $init512 = array( // initial values for SHA512
                '6a09e667f3bcc908',
                'bb67ae8584caa73b',
                '3c6ef372fe94f82b',
                'a54ff53a5f1d36f1',
                '510e527fade682d1',
                '9b05688c2b3e6c1f',
                '1f83d9abfb41bd6b',
                '5be0cd19137e2179'
            );
            
            for ($i = 0; $i < 8; $i ++) {
                $init384[$i] = new Math_BigInteger($init384[$i], 16);
                $init384[$i]->setPrecision(64);
                $init512[$i] = new Math_BigInteger($init512[$i], 16);
                $init512[$i]->setPrecision(64);
            }
            
            // Initialize table of round constants
            // (first 64 bits of the fractional parts of the cube roots of the first 80 primes 2..409)
            $k = array(
                '428a2f98d728ae22',
                '7137449123ef65cd',
                'b5c0fbcfec4d3b2f',
                'e9b5dba58189dbbc',
                '3956c25bf348b538',
                '59f111f1b605d019',
                '923f82a4af194f9b',
                'ab1c5ed5da6d8118',
                'd807aa98a3030242',
                '12835b0145706fbe',
                '243185be4ee4b28c',
                '550c7dc3d5ffb4e2',
                '72be5d74f27b896f',
                '80deb1fe3b1696b1',
                '9bdc06a725c71235',
                'c19bf174cf692694',
                'e49b69c19ef14ad2',
                'efbe4786384f25e3',
                '0fc19dc68b8cd5b5',
                '240ca1cc77ac9c65',
                '2de92c6f592b0275',
                '4a7484aa6ea6e483',
                '5cb0a9dcbd41fbd4',
                '76f988da831153b5',
                '983e5152ee66dfab',
                'a831c66d2db43210',
                'b00327c898fb213f',
                'bf597fc7beef0ee4',
                'c6e00bf33da88fc2',
                'd5a79147930aa725',
                '06ca6351e003826f',
                '142929670a0e6e70',
                '27b70a8546d22ffc',
                '2e1b21385c26c926',
                '4d2c6dfc5ac42aed',
                '53380d139d95b3df',
                '650a73548baf63de',
                '766a0abb3c77b2a8',
                '81c2c92e47edaee6',
                '92722c851482353b',
                'a2bfe8a14cf10364',
                'a81a664bbc423001',
                'c24b8b70d0f89791',
                'c76c51a30654be30',
                'd192e819d6ef5218',
                'd69906245565a910',
                'f40e35855771202a',
                '106aa07032bbd1b8',
                '19a4c116b8d2d0c8',
                '1e376c085141ab53',
                '2748774cdf8eeb99',
                '34b0bcb5e19b48a8',
                '391c0cb3c5c95a63',
                '4ed8aa4ae3418acb',
                '5b9cca4f7763e373',
                '682e6ff3d6b2b8a3',
                '748f82ee5defb2fc',
                '78a5636f43172f60',
                '84c87814a1f0ab72',
                '8cc702081a6439ec',
                '90befffa23631e28',
                'a4506cebde82bde9',
                'bef9a3f7b2c67915',
                'c67178f2e372532b',
                'ca273eceea26619c',
                'd186b8c721c0c207',
                'eada7dd6cde0eb1e',
                'f57d4f7fee6ed178',
                '06f067aa72176fba',
                '0a637dc5a2c898a6',
                '113f9804bef90dae',
                '1b710b35131c471b',
                '28db77f523047d84',
                '32caab7b40c72493',
                '3c9ebe0a15c9bebc',
                '431d67c49c100d4c',
                '4cc5d4becb3e42b6',
                '597f299cfc657e2a',
                '5fcb6fab3ad6faec',
                '6c44198c4a475817'
            );
            
            for ($i = 0; $i < 80; $i ++) {
                $k[$i] = new Math_BigInteger($k[$i], 16);
            }
        }
        
        $hash = $this->l == 48 ? $init384 : $init512;
        
        // Pre-processing
        $length = strlen($m);
        // to round to nearest 112 mod 128, we'll add 128 - (length + (128 - 112)) % 128
        $m .= str_repeat(chr(0), 128 - (($length + 16) & 0x7F));
        $m[$length] = chr(0x80);
        // we don't support hashing strings 512MB long
        $m .= pack('N4', 0, 0, 0, $length << 3);
        
        // Process the message in successive 1024-bit chunks
        $chunks = str_split($m, 128);
        foreach ($chunks as $chunk) {
            $w = array();
            for ($i = 0; $i < 16; $i ++) {
                $temp = new Math_BigInteger($this->_string_shift($chunk, 8), 256);
                $temp->setPrecision(64);
                $w[] = $temp;
            }
            
            // Extend the sixteen 32-bit words into eighty 32-bit words
            for ($i = 16; $i < 80; $i ++) {
                $temp = array(
                    $w[$i - 15]->bitwise_rightRotate(1),
                    $w[$i - 15]->bitwise_rightRotate(8),
                    $w[$i - 15]->bitwise_rightShift(7)
                );
                $s0 = $temp[0]->bitwise_xor($temp[1]);
                $s0 = $s0->bitwise_xor($temp[2]);
                $temp = array(
                    $w[$i - 2]->bitwise_rightRotate(19),
                    $w[$i - 2]->bitwise_rightRotate(61),
                    $w[$i - 2]->bitwise_rightShift(6)
                );
                $s1 = $temp[0]->bitwise_xor($temp[1]);
                $s1 = $s1->bitwise_xor($temp[2]);
                $w[$i] = $w[$i - 16]->copy();
                $w[$i] = $w[$i]->add($s0);
                $w[$i] = $w[$i]->add($w[$i - 7]);
                $w[$i] = $w[$i]->add($s1);
            }
            
            // Initialize hash value for this chunk
            $a = $hash[0]->copy();
            $b = $hash[1]->copy();
            $c = $hash[2]->copy();
            $d = $hash[3]->copy();
            $e = $hash[4]->copy();
            $f = $hash[5]->copy();
            $g = $hash[6]->copy();
            $h = $hash[7]->copy();
            
            // Main loop
            for ($i = 0; $i < 80; $i ++) {
                $temp = array(
                    $a->bitwise_rightRotate(28),
                    $a->bitwise_rightRotate(34),
                    $a->bitwise_rightRotate(39)
                );
                $s0 = $temp[0]->bitwise_xor($temp[1]);
                $s0 = $s0->bitwise_xor($temp[2]);
                $temp = array(
                    $a->bitwise_and($b),
                    $a->bitwise_and($c),
                    $b->bitwise_and($c)
                );
                $maj = $temp[0]->bitwise_xor($temp[1]);
                $maj = $maj->bitwise_xor($temp[2]);
                $t2 = $s0->add($maj);
                
                $temp = array(
                    $e->bitwise_rightRotate(14),
                    $e->bitwise_rightRotate(18),
                    $e->bitwise_rightRotate(41)
                );
                $s1 = $temp[0]->bitwise_xor($temp[1]);
                $s1 = $s1->bitwise_xor($temp[2]);
                $temp = array(
                    $e->bitwise_and($f),
                    $g->bitwise_and($e->bitwise_not())
                );
                $ch = $temp[0]->bitwise_xor($temp[1]);
                $t1 = $h->add($s1);
                $t1 = $t1->add($ch);
                $t1 = $t1->add($k[$i]);
                $t1 = $t1->add($w[$i]);
                
                $h = $g->copy();
                $g = $f->copy();
                $f = $e->copy();
                $e = $d->add($t1);
                $d = $c->copy();
                $c = $b->copy();
                $b = $a->copy();
                $a = $t1->add($t2);
            }
            
            // Add this chunk's hash to result so far
            $hash = array(
                $hash[0]->add($a),
                $hash[1]->add($b),
                $hash[2]->add($c),
                $hash[3]->add($d),
                $hash[4]->add($e),
                $hash[5]->add($f),
                $hash[6]->add($g),
                $hash[7]->add($h)
            );
        }
        
        // Produce the final hash value (big-endian)
        // (Crypt_Hash::hash() trims the output for hashes but not for HMACs. as such, we trim the output here)
        $temp = $hash[0]->toBytes() . $hash[1]->toBytes() . $hash[2]->toBytes() . $hash[3]->toBytes() . $hash[4]->toBytes() . $hash[5]->toBytes();
        if ($this->l != 48) {
            $temp .= $hash[6]->toBytes() . $hash[7]->toBytes();
        }
        
        return $temp;
    }

    /**
     * Right Rotate
     *
     * @access private
     * @param Integer $int            
     * @param Integer $amt            
     * @see _sha256()
     * @return Integer
     */
    function _rightRotate($int, $amt)
    {
        $invamt = 32 - $amt;
        $mask = (1 << $invamt) - 1;
        return (($int << $invamt) & 0xFFFFFFFF) | (($int >> $amt) & $mask);
    }

    /**
     * Right Shift
     *
     * @access private
     * @param Integer $int            
     * @param Integer $amt            
     * @see _sha256()
     * @return Integer
     */
    function _rightShift($int, $amt)
    {
        $mask = (1 << (32 - $amt)) - 1;
        return ($int >> $amt) & $mask;
    }

    /**
     * Not
     *
     * @access private
     * @param Integer $int            
     * @see _sha256()
     * @return Integer
     */
    function _not($int)
    {
        return ~ $int & 0xFFFFFFFF;
    }

    /**
     * Add
     *
     * _sha256() adds multiple unsigned 32-bit integers. Since PHP doesn't support unsigned integers and since the
     * possibility of overflow exists, care has to be taken. Math_BigInteger() could be used but this should be faster.
     *
     * @param Integer $...            
     * @return Integer
     * @see _sha256()
     * @access private
     */
    function _add()
    {
        static $mod;
        if (!isset($mod)) {
            $mod = pow(2, 32);
        }
        
        $result = 0;
        $arguments = func_get_args();
        foreach ($arguments as $argument) {
            $result += $argument < 0 ? ($argument & 0x7FFFFFFF) + 0x80000000 : $argument;
        }
        
        return fmod($result, $mod);
    }

    /**
     * String Shift
     *
     * Inspired by array_shift
     *
     * @param String $string            
     * @param
     *            optional Integer $index
     * @return String
     * @access private
     */
    function _string_shift(&$string, $index = 1)
    {
        $substr = substr($string, 0, $index);
        $string = substr($string, $index);
        return $substr;
    }
}
