mcs/class/System.Security/System.Security.Cryptography.Xml/SignedXml.cs

   1 //
   2 // SignedXml.cs - SignedXml implementation for XML Signature
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //      Atsushi Enomoto <atsushi@ximian.com>
   7 //      Tim Coleman <tim@timcoleman.com>
   8 //
   9 // (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
  10 // Copyright (C) Tim Coleman, 2004
  11 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System.Collections;
  34 using System.IO;
  35 using System.Runtime.InteropServices;
  36 using System.Security.Cryptography;
  37 using System.Security.Policy;
  38 using System.Net;
  39 using System.Text;
  40 using System.Xml;
  41
  42 #if NET_2_0
  43 using System.Security.Cryptography.X509Certificates;
  44 #endif
  45
  46 namespace System.Security.Cryptography.Xml {
  47
  48         public class SignedXml {
  49
  50                 public const string XmlDsigCanonicalizationUrl                  = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315";
  51                 public const string XmlDsigCanonicalizationWithCommentsUrl      = XmlDsigCanonicalizationUrl + "#WithComments";
  52                 public const string XmlDsigDSAUrl                               = XmlDsigNamespaceUrl + "dsa-sha1";
  53                 public const string XmlDsigHMACSHA1Url                          = XmlDsigNamespaceUrl + "hmac-sha1";
  54                 public const string XmlDsigMinimalCanonicalizationUrl           = XmlDsigNamespaceUrl + "minimal";
  55                 public const string XmlDsigNamespaceUrl                         = "http://www.w3.org/2000/09/xmldsig#";
  56                 public const string XmlDsigRSASHA1Url                           = XmlDsigNamespaceUrl + "rsa-sha1";
  57                 public const string XmlDsigSHA1Url                              = XmlDsigNamespaceUrl + "sha1";
  58
  59 #if NET_2_0
  60                 public const string XmlDecryptionTransformUrl                   = "http://www.w3.org/2002/07/decrypt#XML";
  61                 public const string XmlDsigBase64TransformUrl                   = XmlDsigNamespaceUrl + "base64";
  62                 public const string XmlDsigC14NTransformUrl                     = XmlDsigCanonicalizationUrl;
  63                 public const string XmlDsigC14NWithCommentsTransformUrl         = XmlDsigCanonicalizationWithCommentsUrl;
  64                 public const string XmlDsigEnvelopedSignatureTransformUrl       = XmlDsigNamespaceUrl + "enveloped-signature";
  65                 public const string XmlDsigExcC14NTransformUrl                  = "http://www.w3.org/2001/10/xml-exc-c14n#";
  66                 public const string XmlDsigExcC14NWithCommentsTransformUrl      = XmlDsigExcC14NTransformUrl + "WithComments";
  67                 public const string XmlDsigXPathTransformUrl                    = "http://www.w3.org/TR/1999/REC-xpath-19991116";
  68                 public const string XmlDsigXsltTransformUrl                     = "http://www.w3.org/TR/1999/REC-xslt-19991116";
  69                 public const string XmlLicenseTransformUrl                      = "urn:mpeg:mpeg21:2003:01-REL-R-NS:licenseTransform";
  70
  71                 private EncryptedXml encryptedXml;
  72 #endif
  73
  74                 protected Signature m_signature;
  75                 private AsymmetricAlgorithm key;
  76                 protected string m_strSigningKeyName;
  77                 private XmlDocument envdoc;
  78                 private IEnumerator pkEnumerator;
  79                 private XmlElement signatureElement;
  80                 private Hashtable hashes;
  81                 // FIXME: enable it after CAS implementation
  82 #if false //NET_1_1
  83                 private XmlResolver xmlResolver = new XmlSecureResolver (new XmlUrlResolver (), new Evidence ());
  84 #else
  85                 private XmlResolver xmlResolver = new XmlUrlResolver ();
  86 #endif
  87                 private ArrayList manifests;
  88
  89                 private static readonly char [] whitespaceChars = new char [] {' ', '\r', '\n', '\t'};
  90
  91                 public SignedXml ()
  92                 {
  93                         m_signature = new Signature ();
  94                         m_signature.SignedInfo = new SignedInfo ();
  95                         hashes = new Hashtable (2); // 98% SHA1 for now
  96                 }
  97
  98                 public SignedXml (XmlDocument document) : this ()
  99                 {
 100                         if (document == null)
 101                                 throw new ArgumentNullException ("document");
 102                         envdoc = document;
 103                 }
 104
 105                 public SignedXml (XmlElement elem) : this ()
 106                 {
 107                         if (elem == null)
 108                                 throw new ArgumentNullException ("elem");
 109                         envdoc = new XmlDocument ();
 110                         envdoc.LoadXml (elem.OuterXml);
 111                 }
 112
 113 #if NET_2_0
 114                 [ComVisible (false)]
 115                 public EncryptedXml EncryptedXml {
 116                         get { return encryptedXml; }
 117                         set { encryptedXml = value; }
 118                 }
 119 #endif
 120
 121                 public KeyInfo KeyInfo {
 122                         get { return m_signature.KeyInfo; }
 123                         set { m_signature.KeyInfo = value; }
 124                 }
 125
 126                 public Signature Signature {
 127                         get { return m_signature; }
 128                 }
 129
 130                 public string SignatureLength {
 131                         get { return m_signature.SignedInfo.SignatureLength; }
 132                 }
 133
 134                 public string SignatureMethod {
 135                         get { return m_signature.SignedInfo.SignatureMethod; }
 136                 }
 137
 138                 public byte[] SignatureValue {
 139                         get { return m_signature.SignatureValue; }
 140                 }
 141
 142                 public SignedInfo SignedInfo {
 143                         get { return m_signature.SignedInfo; }
 144                 }
 145
 146                 public AsymmetricAlgorithm SigningKey {
 147                         get { return key; }
 148                         set { key = value; }
 149                 }
 150
 151                 // NOTE: CryptoAPI related ? documented as fx internal
 152                 public string SigningKeyName {
 153                         get { return m_strSigningKeyName; }
 154                         set { m_strSigningKeyName = value; }
 155                 }
 156
 157                 public void AddObject (DataObject dataObject)
 158                 {
 159                         m_signature.AddObject (dataObject);
 160                 }
 161
 162                 public void AddReference (Reference reference)
 163                 {
 164                         m_signature.SignedInfo.AddReference (reference);
 165                 }
 166
 167                 private Stream ApplyTransform (Transform t, XmlDocument input)
 168                 {
 169                         // These transformer modify input document, which should
 170                         // not affect to the input itself.
 171                         if (t is XmlDsigXPathTransform
 172                                 || t is XmlDsigEnvelopedSignatureTransform
 173 #if NET_2_0
 174                                 || t is XmlDecryptionTransform
 175 #endif
 176                         )
 177                                 input = (XmlDocument) input.Clone ();
 178
 179                         t.LoadInput (input);
 180
 181                         if (t is XmlDsigEnvelopedSignatureTransform)
 182                                 // It returns XmlDocument for XmlDocument input.
 183                                 return CanonicalizeOutput (t.GetOutput ());
 184
 185                         object obj = t.GetOutput ();
 186                         if (obj is Stream)
 187                                 return (Stream) obj;
 188                         else if (obj is XmlDocument) {
 189                                 MemoryStream ms = new MemoryStream ();
 190                                 XmlTextWriter xtw = new XmlTextWriter (ms, Encoding.UTF8);
 191                                 ((XmlDocument) obj).WriteTo (xtw);
 192
 193                                 xtw.Flush ();
 194
 195                                 // Rewind to the start of the stream
 196                                 ms.Position = 0;
 197                                 return ms;
 198                         }
 199                         else if (obj == null) {
 200                                 throw new NotImplementedException ("This should not occur. Transform is " + t + ".");
 201                         }
 202                         else {
 203                                 // e.g. XmlDsigXPathTransform returns XmlNodeList
 204                                 return CanonicalizeOutput (obj);
 205                         }
 206                 }
 207
 208                 private Stream CanonicalizeOutput (object obj)
 209                 {
 210                         Transform c14n = GetC14NMethod ();
 211                         c14n.LoadInput (obj);
 212                         return (Stream) c14n.GetOutput ();
 213                 }
 214
 215                 private XmlDocument GetManifest (Reference r)
 216                 {
 217                         XmlDocument doc = new XmlDocument ();
 218                         doc.PreserveWhitespace = true;
 219
 220                         if (r.Uri [0] == '#') {
 221                                 // local manifest
 222                                 if (signatureElement != null) {
 223                                         XmlElement xel = GetIdElement (signatureElement.OwnerDocument, r.Uri.Substring (1));
 224                                         if (xel == null)
 225                                                 throw new CryptographicException ("Manifest targeted by Reference was not found: " + r.Uri.Substring (1));
 226                                         doc.LoadXml (xel.OuterXml);
 227                                         FixupNamespaceNodes (xel, doc.DocumentElement);
 228                                 }
 229                         }
 230                         else if (xmlResolver != null) {
 231                                 // TODO: need testing
 232                                 Stream s = (Stream) xmlResolver.GetEntity (new Uri (r.Uri), null, typeof (Stream));
 233                                 doc.Load (s);
 234                         }
 235
 236                         if (doc.FirstChild != null) {
 237                                 // keep a copy of the manifests to check their references later
 238                                 if (manifests == null)
 239                                         manifests = new ArrayList ();
 240                                 manifests.Add (doc);
 241
 242                                 return doc;
 243                         }
 244                         return null;
 245                 }
 246
 247                 private void FixupNamespaceNodes (XmlElement src, XmlElement dst)
 248                 {
 249                         // add namespace nodes
 250                         foreach (XmlAttribute attr in src.SelectNodes ("namespace::*")) {
 251                                 if (attr.LocalName == "xml")
 252                                         continue;
 253                                 if (attr.OwnerElement == src)
 254                                         continue;
 255                                 dst.SetAttributeNode (dst.OwnerDocument.ImportNode (attr, true) as XmlAttribute);
 256                         }
 257                 }
 258
 259                 [MonoTODO ("Need testing")]
 260                 private byte[] GetReferenceHash (Reference r)
 261                 {
 262                         Stream s = null;
 263                         XmlDocument doc = null;
 264                         if (r.Uri == String.Empty) {
 265                                 doc = envdoc;
 266                         }
 267                         else if (r.Type == XmlSignature.Uri.Manifest) {
 268                                 doc = GetManifest (r);
 269                         }
 270                         else {
 271                                 doc = new XmlDocument ();
 272                                 doc.PreserveWhitespace = true;
 273                                 string objectName = null;
 274
 275                                 if (r.Uri.StartsWith ("#xpointer")) {
 276                                         string uri = string.Join ("", r.Uri.Substring (9).Split (whitespaceChars));
 277                                         if (uri.Length < 2 || uri [0] != '(' || uri [uri.Length - 1] != ')')
 278                                                 // FIXME: how to handle invalid xpointer?
 279                                                 uri = String.Empty;
 280                                         else
 281                                                 uri = uri.Substring (1, uri.Length - 2);
 282                                         if (uri == "/")
 283                                                 doc = envdoc;
 284                                         else if (uri.Length > 6 && uri.StartsWith ("id(") && uri [uri.Length - 1] == ')')
 285                                                 // id('foo'), id("foo")
 286                                                 objectName = uri.Substring (4, uri.Length - 6);
 287                                 }
 288                                 else if (r.Uri [0] == '#') {
 289                                         objectName = r.Uri.Substring (1);
 290                                 }
 291                                 else if (xmlResolver != null) {
 292                                         // TODO: test but doc says that Resolver = null -> no access
 293                                         try {
 294                                                 // no way to know if valid without throwing an exception
 295                                                 Uri uri = new Uri (r.Uri);
 296                                                 s = (Stream) xmlResolver.GetEntity (uri, null, typeof (Stream));
 297                                         }
 298                                         catch {
 299                                                 // may still be a local file (and maybe not xml)
 300                                                 s = File.OpenRead (r.Uri);
 301                                         }
 302                                 }
 303                                 if (objectName != null) {
 304                                         foreach (DataObject obj in m_signature.ObjectList) {
 305                                                 if (obj.Id == objectName) {
 306                                                         XmlElement xel = obj.GetXml ();
 307                                                         doc.LoadXml (xel.OuterXml);
 308                                                         FixupNamespaceNodes (xel, doc.DocumentElement);
 309                                                         break;
 310                                                 }
 311                                         }
 312                                 }
 313                         }
 314
 315                         if (r.TransformChain.Count > 0) {
 316                                 foreach (Transform t in r.TransformChain) {
 317                                         if (s == null) {
 318                                                 s = ApplyTransform (t, doc);
 319                                         }
 320                                         else {
 321                                                 t.LoadInput (s);
 322                                                 object o = t.GetOutput ();
 323                                                 if (o is Stream)
 324                                                         s = (Stream) o;
 325                                                 else
 326                                                         s = CanonicalizeOutput (o);
 327                                         }
 328                                 }
 329                         }
 330                         else if (s == null) {
 331                                 // we must not C14N references from outside the document
 332                                 // e.g. non-xml documents
 333                                 if (r.Uri [0] != '#') {
 334                                         s = new MemoryStream ();
 335                                         doc.Save (s);
 336                                 }
 337                                 else {
 338                                         // apply default C14N transformation
 339                                         s = ApplyTransform (new XmlDsigC14NTransform (), doc);
 340                                 }
 341                         }
 342                         HashAlgorithm digest = GetHash (r.DigestMethod);
 343                         return digest.ComputeHash (s);
 344                 }
 345
 346                 private void DigestReferences ()
 347                 {
 348                         // we must tell each reference which hash algorithm to use
 349                         // before asking for the SignedInfo XML !
 350                         foreach (Reference r in m_signature.SignedInfo.References) {
 351                                 // assume SHA-1 if nothing is specified
 352                                 if (r.DigestMethod == null)
 353                                         r.DigestMethod = XmlDsigSHA1Url;
 354                                 r.DigestValue = GetReferenceHash (r);
 355                         }
 356                 }
 357
 358                 private Transform GetC14NMethod ()
 359                 {
 360                         Transform t = (Transform) CryptoConfig.CreateFromName (m_signature.SignedInfo.CanonicalizationMethod);
 361                         if (t == null)
 362                                 throw new CryptographicException ("Unknown Canonicalization Method {0}", m_signature.SignedInfo.CanonicalizationMethod);
 363                         return t;
 364                 }
 365
 366                 private Stream SignedInfoTransformed ()
 367                 {
 368                         Transform t = GetC14NMethod ();
 369
 370                         if (signatureElement == null) {
 371                                 // when creating signatures
 372                                 XmlDocument doc = new XmlDocument ();
 373                                 doc.PreserveWhitespace = true;
 374                                 doc.LoadXml (m_signature.SignedInfo.GetXml ().OuterXml);
 375                                 if (envdoc != null)
 376                                 foreach (XmlAttribute attr in envdoc.DocumentElement.SelectNodes ("namespace::*")) {
 377                                         if (attr.LocalName == "xml")
 378                                                 continue;
 379                                         if (attr.Prefix == doc.DocumentElement.Prefix)
 380                                                 continue;
 381                                         doc.DocumentElement.SetAttributeNode (doc.ImportNode (attr, true) as XmlAttribute);
 382                                 }
 383                                 t.LoadInput (doc);
 384                         }
 385                         else {
 386                                 // when verifying signatures
 387                                 // TODO - check m_signature.SignedInfo.Id
 388                                 XmlElement el = signatureElement.GetElementsByTagName (XmlSignature.ElementNames.SignedInfo, XmlSignature.NamespaceURI) [0] as XmlElement;
 389                                 StringWriter sw = new StringWriter ();
 390                                 XmlTextWriter xtw = new XmlTextWriter (sw);
 391                                 xtw.WriteStartElement (el.Prefix, el.LocalName, el.NamespaceURI);
 392
 393                                 // context namespace nodes (except for "xmlns:xml")
 394                                 XmlNodeList nl = el.SelectNodes ("namespace::*");
 395                                 foreach (XmlAttribute attr in nl) {
 396                                         if (attr.ParentNode == el)
 397                                                 continue;
 398                                         if (attr.LocalName == "xml")
 399                                                 continue;
 400                                         if (attr.Prefix == el.Prefix)
 401                                                 continue;
 402                                         attr.WriteTo (xtw);
 403                                 }
 404                                 foreach (XmlNode attr in el.Attributes)
 405                                         attr.WriteTo (xtw);
 406                                 foreach (XmlNode n in el.ChildNodes)
 407                                         n.WriteTo (xtw);
 408
 409                                 xtw.WriteEndElement ();
 410                                 byte [] si = Encoding.UTF8.GetBytes (sw.ToString ());
 411
 412                                 MemoryStream ms = new MemoryStream ();
 413                                 ms.Write (si, 0, si.Length);
 414                                 ms.Position = 0;
 415
 416                                 t.LoadInput (ms);
 417                         }
 418                         // C14N and C14NWithComments always return a Stream in GetOutput
 419                         return (Stream) t.GetOutput ();
 420                 }
 421
 422                 // reuse hash - most document will always use the same hash
 423                 private HashAlgorithm GetHash (string algorithm)
 424                 {
 425                         HashAlgorithm hash = (HashAlgorithm) hashes [algorithm];
 426                         if (hash == null) {
 427                                 hash = HashAlgorithm.Create (algorithm);
 428                                 if (hash == null)
 429                                         throw new CryptographicException ("Unknown hash algorithm: {0}", algorithm);
 430                                 hashes.Add (algorithm, hash);
 431                                 // now ready to be used
 432                         }
 433                         else {
 434                                 // important before reusing an hash object
 435                                 hash.Initialize ();
 436                         }
 437                         return hash;
 438                 }
 439
 440                 public bool CheckSignature ()
 441                 {
 442                         return (CheckSignatureInternal (null) != null);
 443                 }
 444
 445                 private bool CheckReferenceIntegrity (ArrayList referenceList)
 446                 {
 447                         if (referenceList == null)
 448                                 return false;
 449
 450                         // check digest (hash) for every reference
 451                         foreach (Reference r in referenceList) {
 452                                 // stop at first broken reference
 453                                 byte[] hash = GetReferenceHash (r);
 454                                 if (! Compare (r.DigestValue, hash))
 455                                         return false;
 456                         }
 457                         return true;
 458                 }
 459
 460                 public bool CheckSignature (AsymmetricAlgorithm key)
 461                 {
 462                         if (key == null)
 463                                 throw new ArgumentNullException ("key");
 464                         return (CheckSignatureInternal (key) != null);
 465                 }
 466
 467                 private AsymmetricAlgorithm CheckSignatureInternal (AsymmetricAlgorithm key)
 468                 {
 469                         pkEnumerator = null;
 470
 471                         if (key != null) {
 472                                 // check with supplied key
 473                                 if (!CheckSignatureWithKey (key))
 474                                         return null;
 475                         }
 476                         else {
 477                                 if (Signature.KeyInfo == null)
 478                                         throw new CryptographicException ("At least one KeyInfo is required.");
 479                                 // no supplied key, iterates all KeyInfo
 480                                 while ((key = GetPublicKey ()) != null) {
 481                                         if (CheckSignatureWithKey (key)) {
 482                                                 break;
 483                                         }
 484                                 }
 485                                 pkEnumerator = null;
 486                                 if (key == null)
 487                                         return null;
 488                         }
 489
 490                         // some parts may need to be downloaded
 491                         // so where doing it last
 492                         if (!CheckReferenceIntegrity (m_signature.SignedInfo.References))
 493                                 return null;
 494
 495                         if (manifests != null) {
 496                                 // do not use foreach as a manifest could contain manifests...
 497                                 for (int i=0; i < manifests.Count; i++) {
 498                                         Manifest manifest = new Manifest ((manifests [i] as XmlDocument).DocumentElement);
 499                                         if (! CheckReferenceIntegrity (manifest.References))
 500                                                 return null;
 501                                 }
 502                         }
 503                         return key;
 504                 }
 505
 506                 // Is the signature (over SignedInfo) valid ?
 507                 private bool CheckSignatureWithKey (AsymmetricAlgorithm key)
 508                 {
 509                         if (key == null)
 510                                 return false;
 511
 512                         SignatureDescription sd = (SignatureDescription) CryptoConfig.CreateFromName (m_signature.SignedInfo.SignatureMethod);
 513                         if (sd == null)
 514                                 return false;
 515
 516                         AsymmetricSignatureDeformatter verifier = (AsymmetricSignatureDeformatter) CryptoConfig.CreateFromName (sd.DeformatterAlgorithm);
 517                         if (verifier == null)
 518                                 return false;
 519
 520                         try {
 521                                 verifier.SetKey (key);
 522                                 verifier.SetHashAlgorithm (sd.DigestAlgorithm);
 523
 524                                 HashAlgorithm hash = GetHash (sd.DigestAlgorithm);
 525                                 // get the hash of the C14N SignedInfo element
 526                                 MemoryStream ms = (MemoryStream) SignedInfoTransformed ();
 527
 528                                 byte[] digest = hash.ComputeHash (ms);
 529                                 return verifier.VerifySignature (digest, m_signature.SignatureValue);
 530                         }
 531                         catch {
 532                                 // e.g. SignatureMethod != AsymmetricAlgorithm type
 533                                 return false;
 534                         }
 535                 }
 536
 537                 private bool Compare (byte[] expected, byte[] actual)
 538                 {
 539                         bool result = ((expected != null) && (actual != null));
 540                         if (result) {
 541                                 int l = expected.Length;
 542                                 result = (l == actual.Length);
 543                                 if (result) {
 544                                         for (int i=0; i < l; i++) {
 545                                                 if (expected[i] != actual[i])
 546                                                         return false;
 547                                         }
 548                                 }
 549                         }
 550                         return result;
 551                 }
 552
 553                 public bool CheckSignature (KeyedHashAlgorithm macAlg)
 554                 {
 555                         if (macAlg == null)
 556                                 throw new ArgumentNullException ("macAlg");
 557
 558                         pkEnumerator = null;
 559
 560                         // Is the signature (over SignedInfo) valid ?
 561                         Stream s = SignedInfoTransformed ();
 562                         if (s == null)
 563                                 return false;
 564
 565                         byte[] actual = macAlg.ComputeHash (s);
 566                         // HMAC signature may be partial
 567                         if (m_signature.SignedInfo.SignatureLength != null) {
 568                                 int length = actual.Length;
 569                                 try {
 570                                         // SignatureLength is in bits
 571                                         length = (Int32.Parse (m_signature.SignedInfo.SignatureLength) >> 3);
 572                                 }
 573                                 catch {
 574                                 }
 575
 576                                 if (length != actual.Length) {
 577                                         byte[] trunked = new byte [length];
 578                                         Buffer.BlockCopy (actual, 0, trunked, 0, length);
 579                                         actual = trunked;
 580                                 }
 581                         }
 582
 583                         if (Compare (m_signature.SignatureValue, actual)) {
 584                                 // some parts may need to be downloaded
 585                                 // so where doing it last
 586                                 return CheckReferenceIntegrity (m_signature.SignedInfo.References);
 587                         }
 588                         return false;
 589                 }
 590
 591 #if NET_2_0
 592                 [MonoTODO]
 593                 [ComVisible (false)]
 594                 public bool CheckSignature (X509Certificate2 certificate, bool verifySignatureOnly)
 595                 {
 596                         throw new NotImplementedException ();
 597                 }
 598 #endif
 599
 600                 public bool CheckSignatureReturningKey (out AsymmetricAlgorithm signingKey)
 601                 {
 602                         signingKey = CheckSignatureInternal (null);
 603                         return (signingKey != null);
 604                 }
 605
 606                 public void ComputeSignature ()
 607                 {
 608                         if (key != null) {
 609                                 // required before hashing
 610                                 m_signature.SignedInfo.SignatureMethod = key.SignatureAlgorithm;
 611                                 DigestReferences ();
 612
 613                                 AsymmetricSignatureFormatter signer = null;
 614                                 // in need for a CryptoConfig factory
 615                                 if (key is DSA)
 616                                         signer = new DSASignatureFormatter (key);
 617                                 else if (key is RSA)
 618                                         signer = new RSAPKCS1SignatureFormatter (key);
 619
 620                                 if (signer != null) {
 621                                         SignatureDescription sd = (SignatureDescription) CryptoConfig.CreateFromName (m_signature.SignedInfo.SignatureMethod);
 622
 623                                         HashAlgorithm hash = GetHash (sd.DigestAlgorithm);
 624                                         // get the hash of the C14N SignedInfo element
 625                                         byte[] digest = hash.ComputeHash (SignedInfoTransformed ());
 626
 627                                         signer.SetHashAlgorithm ("SHA1");
 628                                         m_signature.SignatureValue = signer.CreateSignature (digest);
 629                                 }
 630                         }
 631                 }
 632
 633                 public void ComputeSignature (KeyedHashAlgorithm macAlg)
 634                 {
 635                         if (macAlg == null)
 636                                 throw new ArgumentNullException ("macAlg");
 637
 638                         if (macAlg is HMACSHA1) {
 639                                 DigestReferences ();
 640
 641                                 m_signature.SignedInfo.SignatureMethod = XmlDsigHMACSHA1Url;
 642                                 m_signature.SignatureValue = macAlg.ComputeHash (SignedInfoTransformed ());
 643                         }
 644                         else
 645                                 throw new CryptographicException ("unsupported algorithm");
 646                 }
 647
 648                 public virtual XmlElement GetIdElement (XmlDocument document, string idValue)
 649                 {
 650                         // this works only if there's a DTD or XSD available to define the ID
 651                         XmlElement xel = document.GetElementById (idValue);
 652                         if (xel == null) {
 653                                 // search an "undefined" ID
 654                                 xel = (XmlElement) document.SelectSingleNode ("//*[@Id='" + idValue + "']");
 655                         }
 656                         return xel;
 657                 }
 658
 659                 // According to book ".NET Framework Security" this method
 660                 // iterates all possible keys then return null
 661                 protected virtual AsymmetricAlgorithm GetPublicKey ()
 662                 {
 663                         if (m_signature.KeyInfo == null)
 664                                 return null;
 665
 666                         if (pkEnumerator == null) {
 667                                 pkEnumerator = m_signature.KeyInfo.GetEnumerator ();
 668                         }
 669
 670                         if (pkEnumerator.MoveNext ()) {
 671                                 AsymmetricAlgorithm key = null;
 672                                 KeyInfoClause kic = (KeyInfoClause) pkEnumerator.Current;
 673
 674                                 if (kic is DSAKeyValue)
 675                                         key = DSA.Create ();
 676                                 else if (kic is RSAKeyValue)
 677                                         key = RSA.Create ();
 678
 679                                 if (key != null) {
 680                                         key.FromXmlString (kic.GetXml ().InnerXml);
 681                                         return key;
 682                                 }
 683                         }
 684                         return null;
 685                 }
 686
 687                 public XmlElement GetXml ()
 688                 {
 689                         return m_signature.GetXml (envdoc);
 690                 }
 691
 692                 public void LoadXml (XmlElement value)
 693                 {
 694                         if (value == null)
 695                                 throw new ArgumentNullException ("value");
 696
 697                         signatureElement = value;
 698                         m_signature.LoadXml (value);
 699 #if NET_2_0
 700                         // Need to give the EncryptedXml object to the
 701                         // XmlDecryptionTransform to give it a fighting
 702                         // chance at decrypting the document.
 703                         foreach (Reference r in m_signature.SignedInfo.References) {
 704                                 foreach (Transform t in r.TransformChain) {
 705                                         if (t is XmlDecryptionTransform)
 706                                                 ((XmlDecryptionTransform) t).EncryptedXml = EncryptedXml;
 707                                 }
 708                         }
 709 #endif
 710                 }
 711
 712 #if NET_1_1
 713                 [ComVisible (false)]
 714                 public XmlResolver Resolver {
 715                         set { xmlResolver = value; }
 716                 }
 717 #endif
 718         }
 719 }