<?php
/**
 * Transparent SHA-256 Implementation for PHP 4 and PHP 5
 *
 * Author: Perry McGee (pmcgee@nanolink.ca)
 * Website: http://www.nanolink.ca/pub/sha256
 *
 * Copyright (C) 2006,2007,2008,2009 Nanolink Solutions
 *
 * Created: Feb 11, 2006
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation; either
 *    version 2.1 of the License, or (at your option) any later version.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 *    You should have received a copy of the GNU Lesser General Public
 *    License along with this library; if not, write to the Free Software
 *    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *    or see <http://www.gnu.org/licenses/>.
 *
 *  Include:
 *
 *   require_once("[path/]sha256.inc.php");
 *
 *  Usage Options:
 *
 *   1) $shaStr = hash('sha256', $string_to_hash);
 *
 *   2) $shaStr = sha256($string_to_hash[, bool ignore_php5_hash = false]);
 *
 *   3) $obj = new nanoSha2([bool $upper_case_output = false]);
 *      $shaStr = $obj->hash($string_to_hash[, bool $ignore_php5_hash = false]);
 *
 * Reference: http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html
 *
 * 2007-12-13: Cleaned up for initial public release
 * 2008-05-10: Moved all helper functions into a class.  API access unchanged.
 * 2009-06-23: Created abstraction of hash() routine
 * 2009-07-23: Added detection of 32 vs 64bit platform, and patches.
 *             Ability to define "_NANO_SHA2_UPPER" to yeild upper case hashes.
 * 2009-08-01: Added ability to attempt to use mhash() prior to running pure
 *             php code.
 *
 * 2010-06-10: Added support for 16bytes char and utf8 in string
 *
 * NOTE: Some sporadic versions of PHP do not handle integer overflows the
 *       same as the majority of builds.  If you get hash results of:
 *        7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff
 *
 *       If you do not have permissions to change PHP versions (if you did
 *       you'd probably upgrade to PHP 5 anyway) it is advised you install a
 *       module that will allow you to use their hashing routines, examples are:
 *       - mhash module : http://ca3.php.net/mhash
 *       - Suhosin : http://www.hardened-php.net/suhosin/
 *
 *       If you install the Suhosin module, this script will transparently
 *       use their routine and define the PHP routine as _nano_sha256().
 *
 *       If the mhash module is present, and $ignore_php5_hash = false the
 *       script will attempt to use the output from mhash prior to running
 *       the PHP code.
 *
 * @package SPIP\Core\Authentification\Sha256
 */
if (!class_exists('nanoSha2')) {
	/**
	 * Classe de calcul d'un SHA
	 */
	class nanoSha2 {
		// php 4 - 5 compatable class properties
		/** Le résultat doit être passé en majuscule ?
		 *
		 * @var bool
		 */
		var $toUpper;
		/** 32 ou 64 bits ?
		 *
		 * @var int
		 */
		var $platform;
		/** bytes par caractères */
		var $bytesString = 16;

		/**
		 * Constructor
		 *
		 * @param bool $toUpper
		 */
		function __construct($toUpper = false) {
			// Determine if the caller wants upper case or not.
			$this->toUpper = is_bool($toUpper)
				? $toUpper
				: ((defined('_NANO_SHA2_UPPER')) ? true : false);

			// Deteremine if the system is 32 or 64 bit.
			$tmpInt = (int)4294967295;
			$this->platform = ($tmpInt > 0) ? 64 : 32;
		}

		/**
		 * Here are the bitwise and functions as defined in FIPS180-2 Standard
		 *
		 * @param int $x
		 * @param int $y
		 * @param int $n
		 * @return int
		 */
		function addmod2n($x, $y, $n = 4294967296)      // Z = (X + Y) mod 2^32
		{
			$mask = 0x80000000;

			if ($x < 0) {
				$x &= 0x7FFFFFFF;
				$x = (float)$x+$mask;
			}

			if ($y < 0) {
				$y &= 0x7FFFFFFF;
				$y = (float)$y+$mask;
			}

			$r = $x+$y;

			if ($r >= $n) {
				while ($r >= $n) {
					$r -= $n;
				}
			}

			return (int)$r;
		}

		/**
		 * Logical bitwise right shift (PHP default is arithmetic shift)
		 *
		 * @param int $x
		 * @param int $n
		 * return int
		 */
		function SHR($x, $n)        // x >> n
		{
			if ($n >= 32) {      // impose some limits to keep it 32-bit
				return (int)0;
			}

			if ($n <= 0) {
				return (int)$x;
			}

			$mask = 0x40000000;

			if ($x < 0) {
				$x &= 0x7FFFFFFF;
				$mask = $mask >> ($n-1);

				return ($x >> $n) | $mask;
			}

			return (int)$x >> (int)$n;
		}

		/** ROTR
		 *
		 * @param int $x
		 * @param int $n
		 * @return int
		 */
		function ROTR($x, $n) { return (int)(($this->SHR($x, $n) | ($x << (32-$n)) & 0xFFFFFFFF)); }

		/** Ch
		 *
		 * @param int $x
		 * @param int $y
		 * @param int $z
		 * @return int
		 */
		function Ch($x, $y, $z) { return ($x & $y) ^ ((~$x) & $z); }

		/** Maj
		 *
		 * @param int $x
		 * @param int $y
		 * @param int $z
		 * @return int
		 */
		function Maj($x, $y, $z) { return ($x & $y) ^ ($x & $z) ^ ($y & $z); }

		/** Sigma0
		 *
		 * @param int $x
		 * @return int
		 */
		function Sigma0($x) { return (int)($this->ROTR($x, 2) ^ $this->ROTR($x, 13) ^ $this->ROTR($x, 22)); }

		/** Sigma1
		 *
		 * @param int $x
		 * @return int
		 */
		function Sigma1($x) { return (int)($this->ROTR($x, 6) ^ $this->ROTR($x, 11) ^ $this->ROTR($x, 25)); }

		/** Sigma_0
		 *
		 * @param int $x
		 * @return int
		 */
		function sigma_0($x) { return (int)($this->ROTR($x, 7) ^ $this->ROTR($x, 18) ^ $this->SHR($x, 3)); }

		/** Sigma_1
		 *
		 * @param int $x
		 * @return int
		 */
		function sigma_1($x) { return (int)($this->ROTR($x, 17) ^ $this->ROTR($x, 19) ^ $this->SHR($x, 10)); }

		/** String 2 ord UTF8
		 *
		 * @param string $s
		 * @param int $byteSize
		 * @return array
		 **/
		function string2ordUTF8($s, &$byteSize) {
			$chars = array();
			// par defaut sur 8bits
			$byteSize = 8;
			$i = 0;
			while ($i < strlen($s)) {
				$chars[] = $this->ordUTF8($s, $i, $bytes);
				$i += $bytes;
				// mais si un char necessite 16bits, on passe tout sur 16
				// sinon on ne concorde pas avec le lecture de la chaine en js
				// et le sha256 js
				if ($bytes > 1) {
					$byteSize = 16;
				}
			}

			return $chars;
		}

		/** Ord UTF8
		 *
		 * @param string $c
		 * @param int $index
		 * @param int $bytes
		 * @return unknown
		 **/
		function ordUTF8($c, $index = 0, &$bytes) {
			$len = strlen($c);
			$bytes = 0;

			if ($index >= $len) {
				return false;
			}

			$h = ord($c[$index]);

			if ($h <= 0x7F) {
				$bytes = 1;

				return $h;
			} else {
				if ($h < 0xC2) {
					// pas utf mais renvoyer quand meme ce qu'on a
					$bytes = 1;

					return $h;
				} else {
					if ($h <= 0xDF && $index < $len-1) {
						$bytes = 2;

						return ($h & 0x1F) << 6 | (ord($c[$index+1]) & 0x3F);
					} else {
						if ($h <= 0xEF && $index < $len-2) {
							$bytes = 3;

							return ($h & 0x0F) << 12 | (ord($c[$index+1]) & 0x3F) << 6
							| (ord($c[$index+2]) & 0x3F);
						} else {
							if ($h <= 0xF4 && $index < $len-3) {
								$bytes = 4;

								return ($h & 0x0F) << 18 | (ord($c[$index+1]) & 0x3F) << 12
								| (ord($c[$index+2]) & 0x3F) << 6
								| (ord($c[$index+3]) & 0x3F);
							} else {
								// pas utf mais renvoyer quand meme ce qu'on a
								$bytes = 1;

								return $h;
							}
						}
					}
				}
			}
		}

		/** String 2 bin int
		 *
		 * @param string $str
		 * @param int $npad
		 * @return int[]
		 **/
		function string2binint($str, $npad = 512) {
			$bin = array();
			$ords = $this->string2ordUTF8($str, $this->bytesString);
			$npad = $npad/$this->bytesString;
			$length = count($ords);
			$ords[] = 0x80; // append the "1" bit followed by 7 0's
			$pad = ceil(($length+1+32/$this->bytesString)/$npad)*$npad-32/$this->bytesString;
			$ords = array_pad($ords, $pad, 0);
			$mask = (1 << $this->bytesString)-1;
			for ($i = 0; $i < count($ords)*$this->bytesString; $i += $this->bytesString) {
				if (!isset($bin[$i >> 5])) {
					$bin[$i >> 5] = 0;
				} // pour eviter des notices.
				$bin[$i >> 5] |= ($ords[$i/$this->bytesString] & $mask) << (24-$i%32);
			}
			$bin[] = $length*$this->bytesString;

			return $bin;
		}

		/** Array split
		 *
		 * @param array $a
		 * @param int $n
		 * @return array
		 **/
		function array_split($a, $n) {
			$split = array();
			while (count($a) > $n) {
				$s = array();
				for ($i = 0; $i < $n; $i++) {
					$s[] = array_shift($a);
				}
				$split[] = $s;
			}
			if (count($a)) {
				$a = array_pad($a, $n, 0);
				$split[] = $a;
			}

			return $split;
		}

		/**
		 * Process and return the hash.
		 *
		 * @param $str Input string to hash
		 * @param $ig_func Option param to ignore checking for php > 5.1.2
		 * @return string Hexadecimal representation of the message digest
		 */
		function hash($str, $ig_func = true) {
			unset($binStr);     // binary representation of input string
			unset($hexStr);     // 256-bit message digest in readable hex format

			// check for php's internal sha256 function, ignore if ig_func==true
			if ($ig_func == false) {
				if (version_compare(PHP_VERSION, '5.1.2', '>=') AND !defined('_NO_HASH_DEFINED')) {
					return hash("sha256", $str, false);
				} else {
					if (function_exists('mhash') && defined('MHASH_SHA256')) {
						return base64_encode(bin2hex(mhash(MHASH_SHA256, $str)));
					}
				}
			}

			/*
			 * SHA-256 Constants
			 *  Sequence of sixty-four constant 32-bit words representing the
			 *  first thirty-two bits of the fractional parts of the cube roots
			 *  of the first sixtyfour prime numbers.
			 */
			$K = array(
				(int)0x428a2f98,
				(int)0x71374491,
				(int)0xb5c0fbcf,
				(int)0xe9b5dba5,
				(int)0x3956c25b,
				(int)0x59f111f1,
				(int)0x923f82a4,
				(int)0xab1c5ed5,
				(int)0xd807aa98,
				(int)0x12835b01,
				(int)0x243185be,
				(int)0x550c7dc3,
				(int)0x72be5d74,
				(int)0x80deb1fe,
				(int)0x9bdc06a7,
				(int)0xc19bf174,
				(int)0xe49b69c1,
				(int)0xefbe4786,
				(int)0x0fc19dc6,
				(int)0x240ca1cc,
				(int)0x2de92c6f,
				(int)0x4a7484aa,
				(int)0x5cb0a9dc,
				(int)0x76f988da,
				(int)0x983e5152,
				(int)0xa831c66d,
				(int)0xb00327c8,
				(int)0xbf597fc7,
				(int)0xc6e00bf3,
				(int)0xd5a79147,
				(int)0x06ca6351,
				(int)0x14292967,
				(int)0x27b70a85,
				(int)0x2e1b2138,
				(int)0x4d2c6dfc,
				(int)0x53380d13,
				(int)0x650a7354,
				(int)0x766a0abb,
				(int)0x81c2c92e,
				(int)0x92722c85,
				(int)0xa2bfe8a1,
				(int)0xa81a664b,
				(int)0xc24b8b70,
				(int)0xc76c51a3,
				(int)0xd192e819,
				(int)0xd6990624,
				(int)0xf40e3585,
				(int)0x106aa070,
				(int)0x19a4c116,
				(int)0x1e376c08,
				(int)0x2748774c,
				(int)0x34b0bcb5,
				(int)0x391c0cb3,
				(int)0x4ed8aa4a,
				(int)0x5b9cca4f,
				(int)0x682e6ff3,
				(int)0x748f82ee,
				(int)0x78a5636f,
				(int)0x84c87814,
				(int)0x8cc70208,
				(int)0x90befffa,
				(int)0xa4506ceb,
				(int)0xbef9a3f7,
				(int)0xc67178f2
			);

			// Pre-processing: Padding the string
			$binStr = $this->string2binint($str, 512);

			// Parsing the Padded Message (Break into N 512-bit blocks)
			$M = $this->array_split($binStr, 16);

			// Set the initial hash values
			$h[0] = (int)0x6a09e667;
			$h[1] = (int)0xbb67ae85;
			$h[2] = (int)0x3c6ef372;
			$h[3] = (int)0xa54ff53a;
			$h[4] = (int)0x510e527f;
			$h[5] = (int)0x9b05688c;
			$h[6] = (int)0x1f83d9ab;
			$h[7] = (int)0x5be0cd19;

			// loop through message blocks and compute hash. ( For i=1 to N : )
			$N = count($M);
			for ($i = 0; $i < $N; $i++) {
				// Break input block into 16 32bit words (message schedule prep)
				$MI = $M[$i];

				// Initialize working variables
				$_a = (int)$h[0];
				$_b = (int)$h[1];
				$_c = (int)$h[2];
				$_d = (int)$h[3];
				$_e = (int)$h[4];
				$_f = (int)$h[5];
				$_g = (int)$h[6];
				$_h = (int)$h[7];
				unset($_s0);
				unset($_s1);
				unset($_T1);
				unset($_T2);
				$W = array();

				// Compute the hash and update
				for ($t = 0; $t < 16; $t++) {
					// Prepare the first 16 message schedule values as we loop
					$W[$t] = $MI[$t];

					// Compute hash
					$_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)),
						$this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t]);
					$_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));

					// Update working variables
					$_h = $_g;
					$_g = $_f;
					$_f = $_e;
					$_e = $this->addmod2n($_d, $_T1);
					$_d = $_c;
					$_c = $_b;
					$_b = $_a;
					$_a = $this->addmod2n($_T1, $_T2);
				}

				for (; $t < 64; $t++) {
					// Continue building the message schedule as we loop
					$_s0 = $W[($t+1) & 0x0F];
					$_s0 = $this->sigma_0($_s0);
					$_s1 = $W[($t+14) & 0x0F];
					$_s1 = $this->sigma_1($_s1);

					$W[$t & 0xF] = $this->addmod2n($this->addmod2n($this->addmod2n($W[$t & 0xF], $_s0), $_s1), $W[($t+9) & 0x0F]);

					// Compute hash
					$_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)),
						$this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t & 0xF]);
					$_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));

					// Update working variables
					$_h = $_g;
					$_g = $_f;
					$_f = $_e;
					$_e = $this->addmod2n($_d, $_T1);
					$_d = $_c;
					$_c = $_b;
					$_b = $_a;
					$_a = $this->addmod2n($_T1, $_T2);
				}

				$h[0] = $this->addmod2n($h[0], $_a);
				$h[1] = $this->addmod2n($h[1], $_b);
				$h[2] = $this->addmod2n($h[2], $_c);
				$h[3] = $this->addmod2n($h[3], $_d);
				$h[4] = $this->addmod2n($h[4], $_e);
				$h[5] = $this->addmod2n($h[5], $_f);
				$h[6] = $this->addmod2n($h[6], $_g);
				$h[7] = $this->addmod2n($h[7], $_h);
			}

			// Convert the 32-bit words into human readable hexadecimal format.
			$hexStr = sprintf("%08x%08x%08x%08x%08x%08x%08x%08x", $h[0], $h[1], $h[2], $h[3], $h[4], $h[5], $h[6], $h[7]);

			return ($this->toUpper) ? strtoupper($hexStr) : $hexStr;
		}

	}
}

/**
 * Main routine called from an application using this include.
 *
 * General usage:
 *   require_once('sha256.inc.php');
 *   $hashstr = sha256('abc');
 *
 * @Note
 * PHP Strings are limitd to (2^31)-1, so it is not worth it to
 * check for input strings > 2^64 as the FIPS180-2 defines.
 *
 * @param string $str Chaîne dont on veut calculer le SHA
 * @param bool $ig_func
 * @return string Le SHA de la chaîne
 */
function _nano_sha256($str, $ig_func = true) {
	$obj = new nanoSha2((defined('_NANO_SHA2_UPPER')) ? true : false);

	return $obj->hash($str, $ig_func);
}

// 2009-07-23: Added check for function as the Suhosin plugin adds this routine.
if (!function_exists('sha256')) {
	/**
	 * Calcul du SHA256
	 *
	 * @param string $str Chaîne dont on veut calculer le SHA
	 * @param bool $ig_func
	 * @return string Le SHA de la chaîne
	 */
	function sha256($str, $ig_func = true) { return _nano_sha256($str, $ig_func); }
}

// support to give php4 the hash() routine which abstracts this code.
if (!function_exists('hash')) {
	define('_NO_HASH_DEFINED', true);
	/**
	 * Retourne le calcul d'un hachage d'une chaîne (pour PHP4)
	 *
	 * @param string $algo Nom de l'algorythme de hachage
	 * @param string $data Chaîne à hacher
	 * @return string|bool
	 *     Hash de la chaîne
	 *     False si pas d'algo trouvé
	 */
	function hash($algo, $data) {
		if (empty($algo) || !is_string($algo) || !is_string($data)) {
			return false;
		}

		if (function_exists($algo)) {
			return $algo($data);
		}
	}
}