コード例 #1
0
        // 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
            _hashAlgorithm = CryptoHelpers.CreateFromName <HashAlgorithm>(_digestMethod);
            if (_hashAlgorithm == null)
            {
                throw new CryptographicException(SR.Cryptography_Xml_CreateHashAlgorithmFailed);
            }

            // 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;

            byte[] 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 CryptographicException(SR.Format(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 CryptographicException(SR.Format(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 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 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 CryptographicException(SR.Cryptography_Xml_UriNotResolved, _uri);
                }

                // Compute the new hash value
                hashInputStream = SignedXmlDebugLog.LogReferenceData(this, hashInputStream);
                hashval         = _hashAlgorithm.ComputeHash(hashInputStream);
            }
            finally
            {
                if (hashInputStream != null)
                {
                    hashInputStream.Close();
                }
                if (response != null)
                {
                    response.Close();
                }
                if (inputStream != null)
                {
                    inputStream.Close();
                }
            }

            return(hashval);
        }