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   1  <?php
   2  
   3  /**
   4   * Montgomery Private Key Handler
   5   *
   6   * "Naked" Curve25519 private keys can pretty much be any sequence of random 32x bytes so unless
   7   * we have a "hidden" key handler pretty much every 32 byte string will be loaded as a curve25519
   8   * private key even if it probably isn't one by PublicKeyLoader.
   9   *
  10   * "Naked" Curve25519 public keys also a string of 32 bytes so distinguishing between a "naked"
  11   * curve25519 private key and a public key is nigh impossible, hence separate plugins for each
  12   *
  13   * PHP version 5
  14   *
  15   * @category  Crypt
  16   * @package   EC
  17   * @author    Jim Wigginton <[email protected]>
  18   * @copyright 2015 Jim Wigginton
  19   * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
  20   * @link      http://phpseclib.sourceforge.net
  21   */
  22  
  23  namespace phpseclib3\Crypt\EC\Formats\Keys;
  24  
  25  use phpseclib3\Crypt\EC\BaseCurves\Montgomery as MontgomeryCurve;
  26  use phpseclib3\Crypt\EC\Curves\Curve25519;
  27  use phpseclib3\Crypt\EC\Curves\Curve448;
  28  use phpseclib3\Exception\UnsupportedFormatException;
  29  use phpseclib3\Math\BigInteger;
  30  
  31  /**
  32   * Montgomery Curve Private Key Handler
  33   *
  34   * @package EC
  35   * @author  Jim Wigginton <[email protected]>
  36   * @access  public
  37   */
  38  abstract class MontgomeryPrivate
  39  {
  40      /**
  41       * Is invisible flag
  42       *
  43       * @access private
  44       */
  45      const IS_INVISIBLE = true;
  46  
  47      /**
  48       * Break a public or private key down into its constituent components
  49       *
  50       * @access public
  51       * @param string $key
  52       * @param string $password optional
  53       * @return array
  54       */
  55      public static function load($key, $password = '')
  56      {
  57          switch (strlen($key)) {
  58              case 32:
  59                  $curve = new Curve25519();
  60                  break;
  61              case 56:
  62                  $curve = new Curve448();
  63                  break;
  64              default:
  65                  throw new \LengthException('The only supported lengths are 32 and 56');
  66          }
  67  
  68          $components = ['curve' => $curve];
  69          $components['dA'] = new BigInteger($key, 256);
  70          $curve->rangeCheck($components['dA']);
  71          // note that EC::getEncodedCoordinates does some additional "magic" (it does strrev on the result)
  72          $components['QA'] = $components['curve']->multiplyPoint($components['curve']->getBasePoint(), $components['dA']);
  73  
  74          return $components;
  75      }
  76  
  77      /**
  78       * Convert an EC public key to the appropriate format
  79       *
  80       * @access public
  81       * @param \phpseclib3\Crypt\EC\BaseCurves\Montgomery $curve
  82       * @param \phpseclib3\Math\Common\FiniteField\Integer[] $publicKey
  83       * @return string
  84       */
  85      public static function savePublicKey(MontgomeryCurve $curve, array $publicKey)
  86      {
  87          return strrev($publicKey[0]->toBytes());
  88      }
  89  
  90      /**
  91       * Convert a private key to the appropriate format.
  92       *
  93       * @access public
  94       * @param \phpseclib3\Math\BigInteger $privateKey
  95       * @param \phpseclib3\Crypt\EC\BaseCurves\Montgomery $curve
  96       * @param \phpseclib3\Math\Common\FiniteField\Integer[] $publicKey
  97       * @param string $password optional
  98       * @return string
  99       */
 100      public static function savePrivateKey(BigInteger $privateKey, MontgomeryCurve $curve, array $publicKey, $password = '')
 101      {
 102          if (!empty($password) && is_string($password)) {
 103              throw new UnsupportedFormatException('MontgomeryPrivate private keys do not support encryption');
 104          }
 105  
 106          return $privateKey->toBytes();
 107      }
 108  }