securemail/php-gpg/libs/GPG.php

   1 <?php\r
   2 /** @package    php-gpg */\r
   3 \r
   4 /** require supporting files */\r
   5 require_once("GPG/Expanded_Key.php");\r
   6 require_once("GPG/Public_Key.php");\r
   7 require_once("GPG/AES.php");\r
   8 require_once("GPG/globals.php");\r
   9 \r
  10 /**\r
  11  * Pure PHP implementation of PHP/GPG encryption.  \r
  12  * Supports RSA, DSA public key length of 2,4,8,16,512,1024,2048 or 4096\r
  13  * Currently supports only encrypt\r
  14  *\r
  15  * @package php-gpg::Encryption\r
  16  * @link http://www.verysimple.com/\r
  17  * @copyright 1997-2012 VerySimple, Inc.\r
  18  * @license http://www.gnu.org/licenses/gpl.html  GPL\r
  19  * @todo implement decryption\r
  20  * @version 1.1\r
  21  * \r
  22  * @example \r
  23  *              require_once 'libs/GPG.php';\r
  24  *              $gpg = new GPG();\r
  25  *              $pub_key = new GPG_Public_Key($public_key_ascii);\r
  26  *              $encrypted = $gpg->encrypt($pub_key,$plain_text_string);\r
  27  */\r
  28 class GPG \r
  29 {\r
  30 \r
  31         private $width = 16;\r
  32         private $el = array(3, 5, 9, 17, 513, 1025, 2049, 4097);\r
  33         private $version = "1.4.7";\r
  34 \r
  35         private function gpg_encrypt($key, $text) {\r
  36 \r
  37                 $i = 0;\r
  38                 $len = strlen($text);\r
  39                 $iblock = array_fill(0, $this->width, 0);\r
  40                 $rblock = array_fill(0, $this->width, 0);\r
  41                 $ct = array_fill(0, $this->width + 2, 0);\r
  42          \r
  43                 $cipher = "";\r
  44 \r
  45                 if($len % $this->width) {\r
  46                         for($i = ($len % $this->width); $i < $this->width; $i++) $text .= "\0";\r
  47                 }\r
  48          \r
  49                 $ekey = new Expanded_Key($key);\r
  50 \r
  51                 for($i = 0; $i < $this->width; $i++) {\r
  52                         $iblock[$i] = 0;\r
  53                         $rblock[$i] = GPG_Utility::c_random();\r
  54                 }\r
  55 \r
  56 \r
  57                 $iblock = GPG_AES::encrypt($iblock, $ekey);\r
  58                 for($i = 0; $i < $this->width; $i++) {\r
  59                         $ct[$i] = ($iblock[$i] ^= $rblock[$i]);\r
  60                 }\r
  61 \r
  62                 $iblock = GPG_AES::encrypt($iblock, $ekey);\r
  63                 $ct[$this->width]   = ($iblock[0] ^ $rblock[$this->width - 2]);\r
  64                 $ct[$this->width + 1] = ($iblock[1] ^ $rblock[$this->width - 1]);\r
  65          \r
  66                 for($i = 0; $i < $this->width + 2; $i++) $cipher .= chr($ct[$i]);\r
  67 \r
  68                 $iblock = array_slice($ct, 2, $this->width + 2);\r
  69 \r
  70                 for($n = 0; $n < strlen($text); $n += $this->width) {\r
  71                         $iblock = GPG_AES::encrypt($iblock, $ekey);\r
  72                         for($i = 0; $i < $this->width; $i++) {\r
  73                                 $iblock[$i] ^= ord($text[$n + $i]);\r
  74                                 $cipher .= chr($iblock[$i]);\r
  75                         }\r
  76                 }\r
  77          \r
  78                 return substr($cipher, 0, $len + $this->width + 2);\r
  79         }\r
  80 \r
  81         private function gpg_header($tag, $len)\r
  82         {\r
  83                 $h = "";\r
  84                 if ($len < 0x100) {\r
  85                   $h .= chr($tag);\r
  86                   $h .= chr($len);\r
  87                 } else if ($len < 0x10000) {\r
  88                   $tag+=1;\r
  89                   $h .= chr($tag);\r
  90                   $h .= $this->writeNumber($len, 2);\r
  91                 } else {\r
  92                   $tag+=2;\r
  93                   $h .= chr($tag);\r
  94                   $h .= $this->writeNumber($len, 4);\r
  95                 }\r
  96                 return $h;\r
  97         }\r
  98 \r
  99         private function writeNumber($n, $bytes)\r
 100         {\r
 101                 // credits for this function go to OpenPGP.js\r
 102                 $b = '';\r
 103                 for ($i = 0; $i < $bytes; $i++) {\r
 104                   $b .= chr(($n >> (8 * ($bytes - $i - 1))) & 0xff);\r
 105                 }\r
 106                 return $b;\r
 107         }\r
 108 \r
 109         private function gpg_session($key_id, $key_type, $session_key, $public_key)\r
 110         { \r
 111 \r
 112                 $mod = array();\r
 113                 $exp = array();\r
 114                 $enc = "";\r
 115          \r
 116                 $s = base64_decode($public_key);\r
 117                 $l = floor((ord($s[0]) * 256 + ord($s[1]) + 7) / 8);\r
 118                 $mod = mpi2b(substr($s, 0, $l + 2));\r
 119                 if($key_type) {\r
 120                         $grp = array();\r
 121                         $y = array();\r
 122                         $B = array();\r
 123                         $C = array();\r
 124 \r
 125                         $l2 = floor((ord($s[$l + 2]) * 256 + ord($s[$l + 3]) + 7) / 8) + 2;\r
 126                         $grp = mpi2b(substr($s, $l + 2, $l2));\r
 127                         $y = mpi2b(substr($s, $l + 2 + $l2));\r
 128                         $exp[0] = $this->el[GPG_Utility::c_random() & 7];\r
 129                         $B = bmodexp($grp, $exp, $mod);\r
 130                         $C = bmodexp($y, $exp, $mod);\r
 131                 } else {\r
 132                         $exp = mpi2b(substr($s, $l + 2));\r
 133                 }\r
 134 \r
 135                 $c = 0;\r
 136                 $lsk = strlen($session_key);\r
 137                 for($i = 0; $i < $lsk; $i++) $c += ord($session_key[$i]);\r
 138                 $c &= 0xffff;\r
 139 \r
 140                 $lm = ($l - 2) * 8 + 2;\r
 141                 $m = chr($lm / 256) . chr($lm % 256) .\r
 142                         chr(2) . GPG_Utility::s_random($l - $lsk - 6, 1) . "\0" .\r
 143                         chr(7) . $session_key .\r
 144                         chr($c / 256) . chr($c & 0xff);\r
 145 \r
 146                 if($key_type) {\r
 147                         $enc = b2mpi($B) . b2mpi(bmod(bmul(mpi2b($m), $C), $mod));\r
 148                         return $this->gpg_header(0x84,strlen($enc) + 10) .\r
 149                                 chr(3) . $key_id . chr(16) . $enc;\r
 150                 } else {\r
 151                         $enc = b2mpi(bmodexp(mpi2b($m), $exp, $mod));\r
 152                         return $this->gpg_header(0x84, strlen($enc) + 10) .\r
 153                                 chr(3) . $key_id . chr(1) . $enc;\r
 154                 }\r
 155         }\r
 156 \r
 157         private function gpg_literal($text)\r
 158         {\r
 159                 if (strpos($text, "\r\n") === false)\r
 160                         $text = str_replace("\n", "\r\n", $text);\r
 161 \r
 162                 return\r
 163                 $this->gpg_header(0xac, strlen($text) + 10) . "t" .\r
 164                         chr(4) . "file\0\0\0\0" . $text;\r
 165         }\r
 166 \r
 167         private function gpg_data($key, $text)\r
 168         {\r
 169                 $enc = $this->gpg_encrypt($key, $this->gpg_literal($text));\r
 170                 return $this->gpg_header(0xa4, strlen($enc)) . $enc;\r
 171         }\r
 172 \r
 173         /**\r
 174          * GPG Encypts a message to the provided public key\r
 175          *\r
 176          * @param GPG_Public_Key $pk\r
 177          * @param string $plaintext\r
 178          * @return string encrypted text\r
 179          */\r
 180         function encrypt($pk, $plaintext)\r
 181         {\r
 182                 // normalize the public key\r
 183                 $key_id = $pk->GetKeyId();\r
 184                 $key_type = $pk->GetKeyType();\r
 185                 $public_key = $pk->GetPublicKey();\r
 186 \r
 187                 $session_key = GPG_Utility::s_random($this->width, 0);\r
 188                 $key_id = GPG_Utility::hex2bin($key_id);\r
 189                 $cp = $this->gpg_session($key_id, $key_type, $session_key, $public_key) .\r
 190                         $this->gpg_data($session_key, $plaintext);\r
 191 \r
 192                 $code = base64_encode($cp);\r
 193                 $code = wordwrap($code, 64, "\n", 1);\r
 194 \r
 195                 return\r
 196                         "-----BEGIN PGP MESSAGE-----\nVersion: VerySimple PHP-GPG v".$this->version."\n\n" .\r
 197                         $code . "\n=" . base64_encode(GPG_Utility::crc24($cp)) .\r
 198                         "\n-----END PGP MESSAGE-----\n";\r
 199         }\r
 200 }\r
 201 \r
 202 ?>\r