private void GetC14NDigest(IHash hash) { bool isKeyedHashAlgorithm = hash is MacHashWrapper; if (isKeyedHashAlgorithm || !_bCacheValid || !SignedInfo.CacheValid) { string baseUri = (_containingDocument == null ? null : _containingDocument.BaseURI); XmlResolver resolver = (_bResolverSet ? _xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); XmlDocument doc = Utils.PreProcessElementInput(SignedInfo.GetXml(), resolver, baseUri); // Add non default namespaces in scope CanonicalXmlNodeList namespaces = (_context == null ? null : Utils.GetPropagatedAttributes(_context)); SignedXmlDebugLog.LogNamespacePropagation(this, namespaces); Utils.AddNamespaces(doc.DocumentElement, namespaces); Transform c14nMethodTransform = SignedInfo.CanonicalizationMethodObject; c14nMethodTransform.Resolver = resolver; c14nMethodTransform.BaseURI = baseUri; SignedXmlDebugLog.LogBeginCanonicalization(this, c14nMethodTransform); c14nMethodTransform.LoadInput(doc); SignedXmlDebugLog.LogCanonicalizedOutput(this, c14nMethodTransform); c14nMethodTransform.GetDigestedOutput(hash); _bCacheValid = !isKeyedHashAlgorithm; } }
// What we want to do is pump the input throug the TransformChain and then // hash the output of the chain document is the document context for resolving relative references internal byte[] CalculateHashValue(XmlDocument document, CanonicalXmlNodeList refList) { // refList is a list of elements that might be targets of references // Now's the time to create our hashing algorithm IDigest digest = CryptoHelpers.CreateFromName <IDigest>(_digestMethod); if (digest == null) { IMac mac = CryptoHelpers.CreateFromName <IMac>(_digestMethod); if (mac == null) { throw new System.Security.Cryptography.CryptographicException(SR.Cryptography_Xml_CreateHashAlgorithmFailed); } // For compatibility to corefx' HMAC implementation byte[] randomKey = Utils.GenerateRandomBlock(mac.GetMacSize()); mac.Init(new KeyParameter(randomKey)); _hashAlgorithm = new MacHashWrapper(mac); } else { _hashAlgorithm = new DigestHashWrapper(digest); } // Let's go get the target. string baseUri = (document == null ? System.Environment.CurrentDirectory + "\\" : document.BaseURI); Stream hashInputStream = null; WebResponse response = null; Stream inputStream = null; XmlResolver resolver = null; _hashval = null; try { switch (_refTargetType) { case ReferenceTargetType.Stream: // This is the easiest case. We already have a stream, so just pump it through the TransformChain resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); hashInputStream = TransformChain.TransformToOctetStream((Stream)_refTarget, resolver, baseUri); break; case ReferenceTargetType.UriReference: // Second-easiest case -- dereference the URI & pump through the TransformChain // handle the special cases where the URI is null (meaning whole doc) // or the URI is just a fragment (meaning a reference to an embedded Object) if (_uri == null) { // We need to create a DocumentNavigator out of the XmlElement resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); // In the case of a Uri-less reference, we will simply pass null to the transform chain. // The first transform in the chain is expected to know how to retrieve the data to hash. hashInputStream = TransformChain.TransformToOctetStream((Stream)null, resolver, baseUri); } else if (_uri.Length == 0) { // This is the self-referential case. First, check that we have a document context. // The Enveloped Signature does not discard comments as per spec; those will be omitted during the transform chain process if (document == null) { throw new System.Security.Cryptography.CryptographicException(string.Format(CultureInfo.CurrentCulture, SR.Cryptography_Xml_SelfReferenceRequiresContext, _uri)); } // Normalize the containing document resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); XmlDocument docWithNoComments = Utils.DiscardComments(Utils.PreProcessDocumentInput(document, resolver, baseUri)); hashInputStream = TransformChain.TransformToOctetStream(docWithNoComments, resolver, baseUri); } else if (_uri[0] == '#') { // If we get here, then we are constructing a Reference to an embedded DataObject // referenced by an Id = attribute. Go find the relevant object bool discardComments = true; string idref = Utils.GetIdFromLocalUri(_uri, out discardComments); if (idref == "xpointer(/)") { // This is a self referencial case if (document == null) { throw new System.Security.Cryptography.CryptographicException(string.Format(CultureInfo.CurrentCulture, SR.Cryptography_Xml_SelfReferenceRequiresContext, _uri)); } // We should not discard comments here!!! resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); hashInputStream = TransformChain.TransformToOctetStream(Utils.PreProcessDocumentInput(document, resolver, baseUri), resolver, baseUri); break; } XmlElement elem = SignedXml.GetIdElement(document, idref); if (elem != null) { _namespaces = Utils.GetPropagatedAttributes(elem.ParentNode as XmlElement); } if (elem == null) { // Go throw the referenced items passed in if (refList != null) { foreach (XmlNode node in refList) { XmlElement tempElem = node as XmlElement; if ((tempElem != null) && (Utils.HasAttribute(tempElem, "Id", SignedXml.XmlDsigNamespaceUrl)) && (Utils.GetAttribute(tempElem, "Id", SignedXml.XmlDsigNamespaceUrl).Equals(idref))) { elem = tempElem; if (_signedXml._context != null) { _namespaces = Utils.GetPropagatedAttributes(_signedXml._context); } break; } } } } if (elem == null) { throw new System.Security.Cryptography.CryptographicException(SR.Cryptography_Xml_InvalidReference); } XmlDocument normDocument = Utils.PreProcessElementInput(elem, resolver, baseUri); // Add the propagated attributes Utils.AddNamespaces(normDocument.DocumentElement, _namespaces); resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); if (discardComments) { // We should discard comments before going into the transform chain XmlDocument docWithNoComments = Utils.DiscardComments(normDocument); hashInputStream = TransformChain.TransformToOctetStream(docWithNoComments, resolver, baseUri); } else { // This is an XPointer reference, do not discard comments!!! hashInputStream = TransformChain.TransformToOctetStream(normDocument, resolver, baseUri); } } else { throw new System.Security.Cryptography.CryptographicException(SR.Cryptography_Xml_UriNotResolved, _uri); } break; case ReferenceTargetType.XmlElement: // We need to create a DocumentNavigator out of the XmlElement resolver = (SignedXml.ResolverSet ? SignedXml._xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri)); hashInputStream = TransformChain.TransformToOctetStream(Utils.PreProcessElementInput((XmlElement)_refTarget, resolver, baseUri), resolver, baseUri); break; default: throw new System.Security.Cryptography.CryptographicException(SR.Cryptography_Xml_UriNotResolved, _uri); } // Compute the new hash value hashInputStream = SignedXmlDebugLog.LogReferenceData(this, hashInputStream); // Default the buffer size to 4K. byte[] buffer = new byte[4096]; int bytesRead; _hashAlgorithm.Reset(); while ((bytesRead = hashInputStream.Read(buffer, 0, buffer.Length)) > 0) { _hashAlgorithm.BlockUpdate(buffer, 0, bytesRead); } _hashval = new byte[_hashAlgorithm.GetHashSize()]; _hashAlgorithm.DoFinal(_hashval, 0); } finally { if (hashInputStream != null) { hashInputStream.Close(); } if (response != null) { response.Close(); } if (inputStream != null) { inputStream.Close(); } } return(_hashval); }