1<?php 2 3/** 4 * XML Formatted DSA Key Handler 5 * 6 * While XKMS defines a private key format for RSA it does not do so for DSA. Quoting that standard: 7 * 8 * "[XKMS] does not specify private key parameters for the DSA signature algorithm since the algorithm only 9 * supports signature modes and so the application of server generated keys and key recovery is of limited 10 * value" 11 * 12 * PHP version 5 13 * 14 * @category Crypt 15 * @package DSA 16 * @author Jim Wigginton <terrafrost@php.net> 17 * @copyright 2015 Jim Wigginton 18 * @license http://www.opensource.org/licenses/mit-license.html MIT License 19 * @link http://phpseclib.sourceforge.net 20 */ 21 22namespace phpseclib3\Crypt\DSA\Formats\Keys; 23 24use ParagonIE\ConstantTime\Base64; 25use phpseclib3\Math\BigInteger; 26use phpseclib3\Common\Functions\Strings; 27 28/** 29 * XML Formatted DSA Key Handler 30 * 31 * @package DSA 32 * @author Jim Wigginton <terrafrost@php.net> 33 * @access public 34 */ 35abstract class XML 36{ 37 /** 38 * Break a public or private key down into its constituent components 39 * 40 * @access public 41 * @param string $key 42 * @param string $password optional 43 * @return array 44 */ 45 public static function load($key, $password = '') 46 { 47 if (!Strings::is_stringable($key)) { 48 throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key)); 49 } 50 51 $use_errors = libxml_use_internal_errors(true); 52 53 $dom = new \DOMDocument(); 54 if (substr($key, 0, 5) != '<?xml') { 55 $key = '<xml>' . $key . '</xml>'; 56 } 57 if (!$dom->loadXML($key)) { 58 throw new \UnexpectedValueException('Key does not appear to contain XML'); 59 } 60 $xpath = new \DOMXPath($dom); 61 $keys = ['p', 'q', 'g', 'y', 'j', 'seed', 'pgencounter']; 62 foreach ($keys as $key) { 63 // $dom->getElementsByTagName($key) is case-sensitive 64 $temp = $xpath->query("//*[translate(local-name(), 'ABCDEFGHIJKLMNOPQRSTUVWXYZ','abcdefghijklmnopqrstuvwxyz')='$key']"); 65 if (!$temp->length) { 66 continue; 67 } 68 $value = new BigInteger(Base64::decode($temp->item(0)->nodeValue), 256); 69 switch ($key) { 70 case 'p': // a prime modulus meeting the [DSS] requirements 71 // Parameters P, Q, and G can be public and common to a group of users. They might be known 72 // from application context. As such, they are optional but P and Q must either both appear 73 // or both be absent 74 $components['p'] = $value; 75 break; 76 case 'q': // an integer in the range 2**159 < Q < 2**160 which is a prime divisor of P-1 77 $components['q'] = $value; 78 break; 79 case 'g': // an integer with certain properties with respect to P and Q 80 $components['g'] = $value; 81 break; 82 case 'y': // G**X mod P (where X is part of the private key and not made public) 83 $components['y'] = $value; 84 // the remaining options do not do anything 85 case 'j': // (P - 1) / Q 86 // Parameter J is available for inclusion solely for efficiency as it is calculatable from 87 // P and Q 88 case 'seed': // a DSA prime generation seed 89 // Parameters seed and pgenCounter are used in the DSA prime number generation algorithm 90 // specified in [DSS]. As such, they are optional but must either both be present or both 91 // be absent 92 case 'pgencounter': // a DSA prime generation counter 93 } 94 } 95 96 libxml_use_internal_errors($use_errors); 97 98 if (!isset($components['y'])) { 99 throw new \UnexpectedValueException('Key is missing y component'); 100 } 101 102 switch (true) { 103 case !isset($components['p']): 104 case !isset($components['q']): 105 case !isset($components['g']): 106 return ['y' => $components['y']]; 107 } 108 109 return $components; 110 } 111 112 /** 113 * Convert a public key to the appropriate format 114 * 115 * See https://www.w3.org/TR/xmldsig-core/#sec-DSAKeyValue 116 * 117 * @access public 118 * @param \phpseclib3\Math\BigInteger $p 119 * @param \phpseclib3\Math\BigInteger $q 120 * @param \phpseclib3\Math\BigInteger $g 121 * @param \phpseclib3\Math\BigInteger $y 122 * @return string 123 */ 124 public static function savePublicKey(BigInteger $p, BigInteger $q, BigInteger $g, BigInteger $y) 125 { 126 return "<DSAKeyValue>\r\n" . 127 ' <P>' . Base64::encode($p->toBytes()) . "</P>\r\n" . 128 ' <Q>' . Base64::encode($q->toBytes()) . "</Q>\r\n" . 129 ' <G>' . Base64::encode($g->toBytes()) . "</G>\r\n" . 130 ' <Y>' . Base64::encode($y->toBytes()) . "</Y>\r\n" . 131 '</DSAKeyValue>'; 132 } 133} 134