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   1  <?php
   2  
   3  /**
   4   * secp192r1
   5   *
   6   * This is the NIST P-192 curve
   7   *
   8   * PHP version 5 and 7
   9   *
  10   * @category  Crypt
  11   * @package   EC
  12   * @author    Jim Wigginton <[email protected]>
  13   * @copyright 2017 Jim Wigginton
  14   * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
  15   * @link      http://pear.php.net/package/Math_BigInteger
  16   */
  17  
  18  namespace phpseclib3\Crypt\EC\Curves;
  19  
  20  use phpseclib3\Crypt\EC\BaseCurves\Prime;
  21  use phpseclib3\Math\BigInteger;
  22  
  23  class secp192r1 extends Prime
  24  {
  25      public function __construct()
  26      {
  27          $modulo = new BigInteger('FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFFFFFFFFFFFF', 16);
  28          $this->setModulo($modulo);
  29  
  30          // algorithm 2.27 from http://diamond.boisestate.edu/~liljanab/MATH308/GuideToECC.pdf#page=66
  31          /* in theory this should be faster than regular modular reductions save for one small issue.
  32             to convert to / from base-2**8 with BCMath you have to call bcmul() and bcdiv() a lot.
  33             to convert to / from base-2**8 with PHP64 you have to call base256_rshift() a lot.
  34             in short, converting to / from base-2**8 is pretty expensive and that expense is
  35             enough to offset whatever else might be gained by a simplified reduction algorithm.
  36             now, if PHP supported unsigned integers things might be different. no bit-shifting
  37             would be required for the PHP engine and it'd be a lot faster. but as is, BigInteger
  38             uses base-2**31 or base-2**26 depending on whether or not the system is has a 32-bit
  39             or a 64-bit OS.
  40          */
  41          /*
  42          $m_length = $this->getLengthInBytes();
  43          $this->setReduction(function($c) use ($m_length) {
  44              $cBytes = $c->toBytes();
  45              $className = $this->className;
  46  
  47              if (strlen($cBytes) > 2 * $m_length) {
  48                  list(, $r) = $c->divide($className::$modulo);
  49                  return $r;
  50              }
  51  
  52              $c = str_pad($cBytes, 48, "\0", STR_PAD_LEFT);
  53              $c = array_reverse(str_split($c, 8));
  54  
  55              $null = "\0\0\0\0\0\0\0\0";
  56              $s1 = new BigInteger($c[2] . $c[1] . $c[0], 256);
  57              $s2 = new BigInteger($null . $c[3] . $c[3], 256);
  58              $s3 = new BigInteger($c[4] . $c[4] . $null, 256);
  59              $s4 = new BigInteger($c[5] . $c[5] . $c[5], 256);
  60  
  61              $r = $s1->add($s2)->add($s3)->add($s4);
  62              while ($r->compare($className::$modulo) >= 0) {
  63                  $r = $r->subtract($className::$modulo);
  64              }
  65  
  66              return $r;
  67          });
  68          */
  69  
  70          $this->setCoefficients(
  71              new BigInteger('FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFFFFFFFFFFFC', 16),
  72              new BigInteger('64210519E59C80E70FA7E9AB72243049FEB8DEECC146B9B1', 16)
  73          );
  74          $this->setBasePoint(
  75              new BigInteger('188DA80EB03090F67CBF20EB43A18800F4FF0AFD82FF1012', 16),
  76              new BigInteger('07192B95FFC8DA78631011ED6B24CDD573F977A11E794811', 16)
  77          );
  78          $this->setOrder(new BigInteger('FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831', 16));
  79      }
  80  }