// 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);
}
