SignedXml.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / whidbey / NetFXspW7 / ndp / clr / src / ManagedLibraries / Security / System / Security / Cryptography / Xml / SignedXml.cs / 1 / SignedXml.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 

// 
// SignedXml.cs 
//
// 21 [....] 2000 
//

namespace System.Security.Cryptography.Xml
{ 
    using System;
    using System.Collections; 
    using System.Globalization; 
    using System.IO;
    using System.Runtime.InteropServices; 
    using System.Security.Cryptography;
    using System.Security.Cryptography.X509Certificates;
    using System.Security.Permissions;
    using System.Xml; 

    [System.Security.Permissions.HostProtection(MayLeakOnAbort = true)] 
    public class SignedXml { 
        /// 
        protected Signature m_signature; 
        /// 
        protected string m_strSigningKeyName;

        private AsymmetricAlgorithm m_signingKey; 
        private XmlDocument m_containingDocument = null;
        private IEnumerator m_keyInfoEnum = null; 
        private X509Certificate2Collection m_x509Collection = null; 
        private IEnumerator m_x509Enum = null;
 
        private bool[] m_refProcessed = null;
        private int[] m_refLevelCache = null;

        internal XmlResolver m_xmlResolver = null; 
        internal XmlElement m_context = null;
        private bool m_bResolverSet = false; 
 
        // additional HMAC Url identifiers
        private const string XmlDsigMoreHMACMD5Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-md5"; 
        private const string XmlDsigMoreHMACSHA256Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256";
        private const string XmlDsigMoreHMACSHA384Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha384";
        private const string XmlDsigMoreHMACSHA512Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha512";
        private const string XmlDsigMoreHMACRIPEMD160Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-ripemd160"; 

        // defines the XML encryption processing rules 
        private EncryptedXml m_exml = null; 

        // 
        // public constant Url identifiers most frequently used within the XML Signature classes
        //

        public const string XmlDsigNamespaceUrl = "http://www.w3.org/2000/09/xmldsig#"; 
        public const string XmlDsigMinimalCanonicalizationUrl = "http://www.w3.org/2000/09/xmldsig#minimal";
        public const string XmlDsigCanonicalizationUrl = XmlDsigC14NTransformUrl; 
        public const string XmlDsigCanonicalizationWithCommentsUrl = XmlDsigC14NWithCommentsTransformUrl; 

        public const string XmlDsigSHA1Url = "http://www.w3.org/2000/09/xmldsig#sha1"; 
        public const string XmlDsigDSAUrl = "http://www.w3.org/2000/09/xmldsig#dsa-sha1";
        public const string XmlDsigRSASHA1Url = "http://www.w3.org/2000/09/xmldsig#rsa-sha1";
        public const string XmlDsigHMACSHA1Url = "http://www.w3.org/2000/09/xmldsig#hmac-sha1";
 
        public const string XmlDsigC14NTransformUrl = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315";
        public const string XmlDsigC14NWithCommentsTransformUrl = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"; 
        public const string XmlDsigExcC14NTransformUrl = "http://www.w3.org/2001/10/xml-exc-c14n#"; 
        public const string XmlDsigExcC14NWithCommentsTransformUrl = "http://www.w3.org/2001/10/xml-exc-c14n#WithComments";
        public const string XmlDsigBase64TransformUrl = "http://www.w3.org/2000/09/xmldsig#base64"; 
        public const string XmlDsigXPathTransformUrl = "http://www.w3.org/TR/1999/REC-xpath-19991116";
        public const string XmlDsigXsltTransformUrl = "http://www.w3.org/TR/1999/REC-xslt-19991116";
        public const string XmlDsigEnvelopedSignatureTransformUrl = "http://www.w3.org/2000/09/xmldsig#enveloped-signature";
        public const string XmlDecryptionTransformUrl = "http://www.w3.org/2002/07/decrypt#XML"; 
        public const string XmlLicenseTransformUrl = "urn:mpeg:mpeg21:2003:01-REL-R-NS:licenseTransform";
 
        // 
        // public constructors
        // 

        public SignedXml() {
            Initialize(null);
        } 

        public SignedXml(XmlDocument document) { 
            if (document == null) 
                throw new ArgumentNullException("document");
            Initialize(document.DocumentElement); 
        }

        public SignedXml(XmlElement elem) {
            if (elem == null) 
                throw new ArgumentNullException("elem");
            Initialize(elem); 
        } 

        private void Initialize (XmlElement element) { 
            m_containingDocument = (element == null ? null : element.OwnerDocument);
            m_context = element;
            m_signature = new Signature();
            m_signature.SignedXml = this; 
            m_signature.SignedInfo = new SignedInfo();
            m_signingKey = null; 
        } 

        // 
        // public properties
        //

        ///  
        public string SigningKeyName {
            get { return m_strSigningKeyName; } 
            set { m_strSigningKeyName = value; } 
        }
 
        [ComVisible(false)]
        public XmlResolver Resolver {
            // This property only has a setter. The rationale for this is that we don't have a good value
            // to return when it has not been explicitely set, as we are using XmlSecureResolver by default 
            set {
                m_xmlResolver = value; 
                m_bResolverSet = true; 
            }
        } 

        internal bool ResolverSet {
            get { return m_bResolverSet; }
        } 

        public AsymmetricAlgorithm SigningKey { 
            get { return m_signingKey; } 
            set { m_signingKey = value; }
        } 

        [ComVisible(false)]
        public EncryptedXml EncryptedXml {
            get { 
                if (m_exml == null)
                    m_exml = new EncryptedXml(m_containingDocument); // default processing rules 
                return m_exml; 
            }
            set { m_exml = value; } 
        }

        public Signature Signature {
            get { return m_signature; } 
        }
 
        public SignedInfo SignedInfo { 
            get { return m_signature.SignedInfo; }
        } 

        public string SignatureMethod  {
            get { return m_signature.SignedInfo.SignatureMethod; }
        } 

        public string SignatureLength { 
            get { return m_signature.SignedInfo.SignatureLength; } 
        }
 
        public byte[] SignatureValue {
            get { return m_signature.SignatureValue; }
        }
 
        public KeyInfo KeyInfo {
            get { return m_signature.KeyInfo; } 
            set { m_signature.KeyInfo = value; } 
        }
 
        public XmlElement GetXml() {
            // If we have a document context, then return a signature element in this context
            if (m_containingDocument != null)
                return m_signature.GetXml(m_containingDocument); 
            else
                return m_signature.GetXml(); 
        } 

        public void LoadXml(XmlElement value) { 
            if (value == null)
                throw new ArgumentNullException("value");

            m_signature.LoadXml(value); 
            m_context = value;
            bCacheValid = false; 
        } 

        // 
        // public methods
        //

        public void AddReference(Reference reference) { 
            m_signature.SignedInfo.AddReference(reference);
        } 
 
        public void AddObject(DataObject dataObject) {
            m_signature.AddObject(dataObject); 
        }

        public bool CheckSignature() {
            bool bRet = false; 
            AsymmetricAlgorithm key;
 
            do { 
                key = GetPublicKey();
                if (key != null) 
                    bRet = CheckSignature(key);
            } while (key != null && bRet == false);

            return bRet; 
        }
 
        public bool CheckSignatureReturningKey(out AsymmetricAlgorithm signingKey) { 
            bool bRet = false;
            AsymmetricAlgorithm key = null; 

            do {
                key = GetPublicKey();
                if (key != null) 
                    bRet = CheckSignature(key);
            } while (key != null && bRet == false); 
 
            signingKey = key;
            return bRet; 
        }

        public bool CheckSignature(AsymmetricAlgorithm key) {
            if (!CheckSignedInfo(key)) 
                return false;
 
            // Now is the time to go through all the references and see if their DigestValues are good 
            return CheckDigestedReferences();
        } 

        public bool CheckSignature(KeyedHashAlgorithm macAlg) {
            if (!CheckSignedInfo(macAlg))
                return false; 

            return CheckDigestedReferences(); 
        } 

        [ComVisible(false)] 
        public bool CheckSignature(X509Certificate2 certificate, bool verifySignatureOnly) {
            if (!CheckSignedInfo(certificate.PublicKey.Key))
                return false;
 
            // Now is the time to go through all the references and see if their DigestValues are good
            if (!CheckDigestedReferences()) 
                return false; 

            if (verifySignatureOnly) 
                return true;

            // Check key usages to make sure it is good for signing.
            foreach (X509Extension extension in certificate.Extensions) { 
                if (String.Compare(extension.Oid.Value, CAPI.szOID_KEY_USAGE, StringComparison.OrdinalIgnoreCase) == 0) {
                    X509KeyUsageExtension keyUsage = new X509KeyUsageExtension(); 
                    keyUsage.CopyFrom(extension); 
                    if ((keyUsage.KeyUsages & X509KeyUsageFlags.DigitalSignature) == 0 &&
                        (keyUsage.KeyUsages & X509KeyUsageFlags.NonRepudiation) == 0) { 
                        return false;
                    }
                    break;
                } 
            }
 
            // Do the chain verification to make sure the certificate is valid. 
            X509Chain chain = new X509Chain();
            chain.ChainPolicy.ExtraStore.AddRange(BuildBagOfCerts()); 
            return chain.Build(certificate);
        }

        public void ComputeSignature() { 
            BuildDigestedReferences();
            // Load the key 
            AsymmetricAlgorithm key = SigningKey; 

            if (key == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_LoadKeyFailed"));

            // Check the signature algorithm associated with the key so that we can accordingly set the signature method
            if (SignedInfo.SignatureMethod == null) { 
                if (key is DSA) {
                    SignedInfo.SignatureMethod = XmlDsigDSAUrl; 
                } else if (key is RSA) { 
                    // Default to RSA-SHA1
                    if (SignedInfo.SignatureMethod == null) 
                        SignedInfo.SignatureMethod = XmlDsigRSASHA1Url;
                } else {
                    throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreatedKeyFailed"));
                } 
            }
 
            // See if there is a signature description class defined in the Config file 
            SignatureDescription signatureDescription = CryptoConfig.CreateFromName(SignedInfo.SignatureMethod) as SignatureDescription;
            if (signatureDescription == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureDescriptionNotCreated"));
            HashAlgorithm hashAlg = signatureDescription.CreateDigest();
            if (hashAlg == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreateHashAlgorithmFailed")); 
            byte[] hashvalue = GetC14NDigest(hashAlg);
            AsymmetricSignatureFormatter asymmetricSignatureFormatter = signatureDescription.CreateFormatter(key); 
            m_signature.SignatureValue = asymmetricSignatureFormatter.CreateSignature(hashAlg); 
        }
 
        public void ComputeSignature(KeyedHashAlgorithm macAlg) {
            if (macAlg == null)
                throw new ArgumentNullException("macAlg");
 
            HMAC hash = macAlg as HMAC;
            if(hash == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureMethodKeyMismatch")); 

            int signatureLength; 
            if (m_signature.SignedInfo.SignatureLength == null)
                signatureLength = hash.HashSize;
            else
                signatureLength = Convert.ToInt32(m_signature.SignedInfo.SignatureLength, null); 
            // signatureLength should be less than hash size
            if (signatureLength < 0 || signatureLength > hash.HashSize) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength")); 
            if (signatureLength % 8 != 0)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength2")); 

            BuildDigestedReferences();
            switch (hash.HashName) {
            case "SHA1": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigHMACSHA1Url;
                break; 
            case "SHA256": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA256Url;
                break; 
            case "SHA384":
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA384Url;
                break;
            case "SHA512": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA512Url;
                break; 
            case "MD5": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACMD5Url;
                break; 
            case "RIPEMD160":
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACRIPEMD160Url;
                break;
            default: 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureMethodKeyMismatch"));
            } 
 
            byte[] hashValue = GetC14NDigest(hash);
            m_signature.SignatureValue = new byte[signatureLength / 8]; 
            Buffer.BlockCopy(hashValue, 0, m_signature.SignatureValue, 0, signatureLength / 8);
        }

        // 
        // virtual methods
        // 
 
        protected virtual AsymmetricAlgorithm GetPublicKey() {
            if (KeyInfo == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_KeyInfoRequired"));

            if (m_x509Enum != null) {
                AsymmetricAlgorithm key = GetNextCertificatePublicKey(); 
                if (key != null)
                    return key; 
            } 

            if (m_keyInfoEnum == null) 
                m_keyInfoEnum = KeyInfo.GetEnumerator();

            // In our implementation, we move to the next KeyInfo clause which is an RSAKeyValue, DSAKeyValue or KeyInfoX509Data
            while (m_keyInfoEnum.MoveNext()) { 
                RSAKeyValue rsaKeyValue = m_keyInfoEnum.Current as RSAKeyValue;
                if (rsaKeyValue != null) 
                    return rsaKeyValue.Key; 

                DSAKeyValue dsaKeyValue = m_keyInfoEnum.Current as DSAKeyValue; 
                if (dsaKeyValue != null)
                    return dsaKeyValue.Key;

                KeyInfoX509Data x509Data = m_keyInfoEnum.Current as KeyInfoX509Data; 
                if (x509Data != null) {
                    m_x509Collection = Utils.BuildBagOfCerts (x509Data, CertUsageType.Verification); 
                    if (m_x509Collection.Count > 0) { 
                        m_x509Enum = m_x509Collection.GetEnumerator();
                        AsymmetricAlgorithm key = GetNextCertificatePublicKey(); 
                        if (key != null)
                            return key;
                    }
                } 
            }
 
            return null; 
        }
 
        private X509Certificate2Collection BuildBagOfCerts () {
            X509Certificate2Collection collection = new X509Certificate2Collection();
            if (this.KeyInfo != null) {
                foreach (KeyInfoClause clause in this.KeyInfo) { 
                    KeyInfoX509Data x509Data = clause as KeyInfoX509Data;
                    if (x509Data != null) 
                        collection.AddRange(Utils.BuildBagOfCerts(x509Data, CertUsageType.Verification)); 
                }
            } 

            return collection;
        }
 
        private AsymmetricAlgorithm GetNextCertificatePublicKey () {
            while (m_x509Enum.MoveNext()) { 
                X509Certificate2 certificate = (X509Certificate2) m_x509Enum.Current; 
                if (certificate != null)
                    return certificate.PublicKey.Key; 
            }

            return null;
        } 

        public virtual XmlElement GetIdElement (XmlDocument document, string idValue) { 
            if (document == null) 
                return null;
 
            // Get the element with idValue
            XmlElement elem = document.GetElementById(idValue);
            if (elem != null)
                return elem; 
            elem = document.SelectSingleNode("//*[@Id=\"" + idValue + "\"]") as XmlElement;
            if (elem != null) 
                return elem; 
            elem = document.SelectSingleNode("//*[@id=\"" + idValue + "\"]") as XmlElement;
            if (elem != null) 
                return elem;
            elem = document.SelectSingleNode("//*[@ID=\"" + idValue + "\"]") as XmlElement;

            return elem; 
        }
 
        // 
        // private methods
        // 

        private bool bCacheValid = false;
        private byte[] _digestedSignedInfo = null;
 
        private byte[] GetC14NDigest (HashAlgorithm hash) {
            if (!bCacheValid || !this.SignedInfo.CacheValid) { 
                string baseUri = (m_containingDocument == null ? null : m_containingDocument.BaseURI); 
                XmlResolver resolver = (m_bResolverSet ? m_xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri));
                XmlDocument doc = Utils.PreProcessElementInput(SignedInfo.GetXml(), resolver, baseUri); 
                // Add non default namespaces in scope
                CanonicalXmlNodeList namespaces = (m_context == null ? null : Utils.GetPropagatedAttributes(m_context));
                Utils.AddNamespaces(doc.DocumentElement, namespaces);
                Transform c14nMethodTransform = SignedInfo.CanonicalizationMethodObject; 
                c14nMethodTransform.Resolver = resolver;
                c14nMethodTransform.BaseURI = baseUri; 
                c14nMethodTransform.LoadInput(doc); 
                _digestedSignedInfo = c14nMethodTransform.GetDigestedOutput(hash);
                bCacheValid = true; 
            }
            return _digestedSignedInfo;
        }
 
        private int GetReferenceLevel (int index, ArrayList references) {
            if (m_refProcessed[index]) return m_refLevelCache[index]; 
            m_refProcessed[index] = true; 
            Reference reference = (Reference) references[index];
            if (reference.Uri == null || reference.Uri.Length == 0 || (reference.Uri.Length > 0 && reference.Uri[0] != '#')) { 
                m_refLevelCache[index] = 0;
                return 0;
            }
            if (reference.Uri.Length > 0 && reference.Uri[0] == '#') { 
                String idref = Utils.ExtractIdFromLocalUri(reference.Uri);
                if (idref == "xpointer(/)") { 
                    m_refLevelCache[index] = 0; 
                    return 0;
                } 
                // If this is pointing to another reference
                for (int j=0; j < references.Count; ++j) {
                    if (((Reference)references[j]).Id == idref) {
                        m_refLevelCache[index] = GetReferenceLevel(j, references) + 1; 
                        return (m_refLevelCache[index]);
                    } 
                } 
                // Then the reference points to an object tag
                m_refLevelCache[index] = 0; 
                return 0;
            }
            // Malformed reference
            throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidReference")); 
        }
 
        private class ReferenceLevelSortOrder : IComparer { 
            private ArrayList m_references = null;
            public ReferenceLevelSortOrder() {} 

            public ArrayList References {
                get { return m_references; }
                set { m_references = value; } 
            }
 
            public int Compare(Object a, Object b) { 
                Reference referenceA = a as Reference;
                Reference referenceB = b as Reference; 

                // Get the indexes
                int iIndexA = 0;
                int iIndexB = 0; 
                int i = 0;
                foreach (Reference reference in References) { 
                    if (reference == referenceA) iIndexA = i; 
                    if (reference == referenceB) iIndexB = i;
                    i++; 
                }

                int iLevelA = referenceA.SignedXml.GetReferenceLevel(iIndexA, References);
                int iLevelB = referenceB.SignedXml.GetReferenceLevel(iIndexB, References); 
                return iLevelA.CompareTo(iLevelB);
            } 
        } 

        private void BuildDigestedReferences() { 
            // Default the DigestMethod and Canonicalization
            ArrayList references = SignedInfo.References;
            // Reset the cache
            m_refProcessed = new bool[references.Count]; 
            m_refLevelCache = new int[references.Count];
 
            ReferenceLevelSortOrder sortOrder = new ReferenceLevelSortOrder(); 
            sortOrder.References = references;
            // Don't alter the order of the references array list 
            ArrayList sortedReferences = new ArrayList();
            foreach (Reference reference in references) {
                sortedReferences.Add(reference);
            } 
            sortedReferences.Sort(sortOrder);
 
            CanonicalXmlNodeList nodeList = new CanonicalXmlNodeList(); 
            foreach (DataObject obj in m_signature.ObjectList) {
                nodeList.Add(obj.GetXml()); 
            }
            foreach (Reference reference in sortedReferences) {
                // If no DigestMethod has yet been set, default it to sha1
                if (reference.DigestMethod == null) 
                    reference.DigestMethod = XmlDsigSHA1Url;
                reference.UpdateHashValue(m_containingDocument, nodeList); 
                // If this reference has an Id attribute, add it 
                if (reference.Id != null)
                    nodeList.Add(reference.GetXml()); 
            }
        }

        private bool CheckDigestedReferences () { 
            ArrayList references = m_signature.SignedInfo.References;
            for (int i = 0; i < references.Count; ++i) { 
                Reference digestedReference = (Reference) references[i]; 
                byte[] calculatedHash = digestedReference.CalculateHashValue(m_containingDocument, m_signature.ReferencedItems);
 
                // Compare both hashes
                if (calculatedHash.Length != digestedReference.DigestValue.Length)
                    return false;
 
                byte[] rgb1 = calculatedHash;
                byte[] rgb2 = digestedReference.DigestValue; 
                for (int j = 0; j < rgb1.Length; ++j) { 
                    if (rgb1[j] != rgb2[j]) return false;
                } 
            }
            return true;
        }
 
        private bool CheckSignedInfo (AsymmetricAlgorithm key) {
            if (key == null) 
                throw new ArgumentNullException("key"); 

            SignatureDescription signatureDescription = CryptoConfig.CreateFromName(SignatureMethod) as SignatureDescription; 
            if (signatureDescription == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureDescriptionNotCreated"));

            // Let's see if the key corresponds with the SignatureMethod 
            Type ta = Type.GetType(signatureDescription.KeyAlgorithm);
            Type tb = key.GetType(); 
            if ((ta != tb) && !ta.IsSubclassOf(tb) && !tb.IsSubclassOf(ta)) 
                // Signature method key mismatch
                return false; 

            HashAlgorithm hashAlgorithm = signatureDescription.CreateDigest();
            if (hashAlgorithm == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreateHashAlgorithmFailed")); 
            byte[] hashval = GetC14NDigest(hashAlgorithm);
 
            AsymmetricSignatureDeformatter asymmetricSignatureDeformatter = signatureDescription.CreateDeformatter(key); 
            return asymmetricSignatureDeformatter.VerifySignature(hashval, m_signature.SignatureValue);
        } 

        private bool CheckSignedInfo (KeyedHashAlgorithm macAlg) {
            if (macAlg == null)
                throw new ArgumentNullException("macAlg"); 

            int signatureLength; 
            if (m_signature.SignedInfo.SignatureLength == null) 
                signatureLength = macAlg.HashSize;
            else 
                signatureLength = Convert.ToInt32(m_signature.SignedInfo.SignatureLength, null);

            // signatureLength should be less than hash size
            if (signatureLength < 0 || signatureLength > macAlg.HashSize) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength"));
            if (signatureLength % 8 != 0) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength2")); 
            if (m_signature.SignatureValue == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureValueRequired")); 
            if (m_signature.SignatureValue.Length != signatureLength / 8)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength"));

            // Calculate the hash 
            byte[] hashValue = GetC14NDigest(macAlg);
            for (int i=0; i
        protected Signature m_signature; 
        /// 
        protected string m_strSigningKeyName;

        private AsymmetricAlgorithm m_signingKey; 
        private XmlDocument m_containingDocument = null;
        private IEnumerator m_keyInfoEnum = null; 
        private X509Certificate2Collection m_x509Collection = null; 
        private IEnumerator m_x509Enum = null;
 
        private bool[] m_refProcessed = null;
        private int[] m_refLevelCache = null;

        internal XmlResolver m_xmlResolver = null; 
        internal XmlElement m_context = null;
        private bool m_bResolverSet = false; 
 
        // additional HMAC Url identifiers
        private const string XmlDsigMoreHMACMD5Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-md5"; 
        private const string XmlDsigMoreHMACSHA256Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256";
        private const string XmlDsigMoreHMACSHA384Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha384";
        private const string XmlDsigMoreHMACSHA512Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-sha512";
        private const string XmlDsigMoreHMACRIPEMD160Url = "http://www.w3.org/2001/04/xmldsig-more#hmac-ripemd160"; 

        // defines the XML encryption processing rules 
        private EncryptedXml m_exml = null; 

        // 
        // public constant Url identifiers most frequently used within the XML Signature classes
        //

        public const string XmlDsigNamespaceUrl = "http://www.w3.org/2000/09/xmldsig#"; 
        public const string XmlDsigMinimalCanonicalizationUrl = "http://www.w3.org/2000/09/xmldsig#minimal";
        public const string XmlDsigCanonicalizationUrl = XmlDsigC14NTransformUrl; 
        public const string XmlDsigCanonicalizationWithCommentsUrl = XmlDsigC14NWithCommentsTransformUrl; 

        public const string XmlDsigSHA1Url = "http://www.w3.org/2000/09/xmldsig#sha1"; 
        public const string XmlDsigDSAUrl = "http://www.w3.org/2000/09/xmldsig#dsa-sha1";
        public const string XmlDsigRSASHA1Url = "http://www.w3.org/2000/09/xmldsig#rsa-sha1";
        public const string XmlDsigHMACSHA1Url = "http://www.w3.org/2000/09/xmldsig#hmac-sha1";
 
        public const string XmlDsigC14NTransformUrl = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315";
        public const string XmlDsigC14NWithCommentsTransformUrl = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"; 
        public const string XmlDsigExcC14NTransformUrl = "http://www.w3.org/2001/10/xml-exc-c14n#"; 
        public const string XmlDsigExcC14NWithCommentsTransformUrl = "http://www.w3.org/2001/10/xml-exc-c14n#WithComments";
        public const string XmlDsigBase64TransformUrl = "http://www.w3.org/2000/09/xmldsig#base64"; 
        public const string XmlDsigXPathTransformUrl = "http://www.w3.org/TR/1999/REC-xpath-19991116";
        public const string XmlDsigXsltTransformUrl = "http://www.w3.org/TR/1999/REC-xslt-19991116";
        public const string XmlDsigEnvelopedSignatureTransformUrl = "http://www.w3.org/2000/09/xmldsig#enveloped-signature";
        public const string XmlDecryptionTransformUrl = "http://www.w3.org/2002/07/decrypt#XML"; 
        public const string XmlLicenseTransformUrl = "urn:mpeg:mpeg21:2003:01-REL-R-NS:licenseTransform";
 
        // 
        // public constructors
        // 

        public SignedXml() {
            Initialize(null);
        } 

        public SignedXml(XmlDocument document) { 
            if (document == null) 
                throw new ArgumentNullException("document");
            Initialize(document.DocumentElement); 
        }

        public SignedXml(XmlElement elem) {
            if (elem == null) 
                throw new ArgumentNullException("elem");
            Initialize(elem); 
        } 

        private void Initialize (XmlElement element) { 
            m_containingDocument = (element == null ? null : element.OwnerDocument);
            m_context = element;
            m_signature = new Signature();
            m_signature.SignedXml = this; 
            m_signature.SignedInfo = new SignedInfo();
            m_signingKey = null; 
        } 

        // 
        // public properties
        //

        ///  
        public string SigningKeyName {
            get { return m_strSigningKeyName; } 
            set { m_strSigningKeyName = value; } 
        }
 
        [ComVisible(false)]
        public XmlResolver Resolver {
            // This property only has a setter. The rationale for this is that we don't have a good value
            // to return when it has not been explicitely set, as we are using XmlSecureResolver by default 
            set {
                m_xmlResolver = value; 
                m_bResolverSet = true; 
            }
        } 

        internal bool ResolverSet {
            get { return m_bResolverSet; }
        } 

        public AsymmetricAlgorithm SigningKey { 
            get { return m_signingKey; } 
            set { m_signingKey = value; }
        } 

        [ComVisible(false)]
        public EncryptedXml EncryptedXml {
            get { 
                if (m_exml == null)
                    m_exml = new EncryptedXml(m_containingDocument); // default processing rules 
                return m_exml; 
            }
            set { m_exml = value; } 
        }

        public Signature Signature {
            get { return m_signature; } 
        }
 
        public SignedInfo SignedInfo { 
            get { return m_signature.SignedInfo; }
        } 

        public string SignatureMethod  {
            get { return m_signature.SignedInfo.SignatureMethod; }
        } 

        public string SignatureLength { 
            get { return m_signature.SignedInfo.SignatureLength; } 
        }
 
        public byte[] SignatureValue {
            get { return m_signature.SignatureValue; }
        }
 
        public KeyInfo KeyInfo {
            get { return m_signature.KeyInfo; } 
            set { m_signature.KeyInfo = value; } 
        }
 
        public XmlElement GetXml() {
            // If we have a document context, then return a signature element in this context
            if (m_containingDocument != null)
                return m_signature.GetXml(m_containingDocument); 
            else
                return m_signature.GetXml(); 
        } 

        public void LoadXml(XmlElement value) { 
            if (value == null)
                throw new ArgumentNullException("value");

            m_signature.LoadXml(value); 
            m_context = value;
            bCacheValid = false; 
        } 

        // 
        // public methods
        //

        public void AddReference(Reference reference) { 
            m_signature.SignedInfo.AddReference(reference);
        } 
 
        public void AddObject(DataObject dataObject) {
            m_signature.AddObject(dataObject); 
        }

        public bool CheckSignature() {
            bool bRet = false; 
            AsymmetricAlgorithm key;
 
            do { 
                key = GetPublicKey();
                if (key != null) 
                    bRet = CheckSignature(key);
            } while (key != null && bRet == false);

            return bRet; 
        }
 
        public bool CheckSignatureReturningKey(out AsymmetricAlgorithm signingKey) { 
            bool bRet = false;
            AsymmetricAlgorithm key = null; 

            do {
                key = GetPublicKey();
                if (key != null) 
                    bRet = CheckSignature(key);
            } while (key != null && bRet == false); 
 
            signingKey = key;
            return bRet; 
        }

        public bool CheckSignature(AsymmetricAlgorithm key) {
            if (!CheckSignedInfo(key)) 
                return false;
 
            // Now is the time to go through all the references and see if their DigestValues are good 
            return CheckDigestedReferences();
        } 

        public bool CheckSignature(KeyedHashAlgorithm macAlg) {
            if (!CheckSignedInfo(macAlg))
                return false; 

            return CheckDigestedReferences(); 
        } 

        [ComVisible(false)] 
        public bool CheckSignature(X509Certificate2 certificate, bool verifySignatureOnly) {
            if (!CheckSignedInfo(certificate.PublicKey.Key))
                return false;
 
            // Now is the time to go through all the references and see if their DigestValues are good
            if (!CheckDigestedReferences()) 
                return false; 

            if (verifySignatureOnly) 
                return true;

            // Check key usages to make sure it is good for signing.
            foreach (X509Extension extension in certificate.Extensions) { 
                if (String.Compare(extension.Oid.Value, CAPI.szOID_KEY_USAGE, StringComparison.OrdinalIgnoreCase) == 0) {
                    X509KeyUsageExtension keyUsage = new X509KeyUsageExtension(); 
                    keyUsage.CopyFrom(extension); 
                    if ((keyUsage.KeyUsages & X509KeyUsageFlags.DigitalSignature) == 0 &&
                        (keyUsage.KeyUsages & X509KeyUsageFlags.NonRepudiation) == 0) { 
                        return false;
                    }
                    break;
                } 
            }
 
            // Do the chain verification to make sure the certificate is valid. 
            X509Chain chain = new X509Chain();
            chain.ChainPolicy.ExtraStore.AddRange(BuildBagOfCerts()); 
            return chain.Build(certificate);
        }

        public void ComputeSignature() { 
            BuildDigestedReferences();
            // Load the key 
            AsymmetricAlgorithm key = SigningKey; 

            if (key == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_LoadKeyFailed"));

            // Check the signature algorithm associated with the key so that we can accordingly set the signature method
            if (SignedInfo.SignatureMethod == null) { 
                if (key is DSA) {
                    SignedInfo.SignatureMethod = XmlDsigDSAUrl; 
                } else if (key is RSA) { 
                    // Default to RSA-SHA1
                    if (SignedInfo.SignatureMethod == null) 
                        SignedInfo.SignatureMethod = XmlDsigRSASHA1Url;
                } else {
                    throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreatedKeyFailed"));
                } 
            }
 
            // See if there is a signature description class defined in the Config file 
            SignatureDescription signatureDescription = CryptoConfig.CreateFromName(SignedInfo.SignatureMethod) as SignatureDescription;
            if (signatureDescription == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureDescriptionNotCreated"));
            HashAlgorithm hashAlg = signatureDescription.CreateDigest();
            if (hashAlg == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreateHashAlgorithmFailed")); 
            byte[] hashvalue = GetC14NDigest(hashAlg);
            AsymmetricSignatureFormatter asymmetricSignatureFormatter = signatureDescription.CreateFormatter(key); 
            m_signature.SignatureValue = asymmetricSignatureFormatter.CreateSignature(hashAlg); 
        }
 
        public void ComputeSignature(KeyedHashAlgorithm macAlg) {
            if (macAlg == null)
                throw new ArgumentNullException("macAlg");
 
            HMAC hash = macAlg as HMAC;
            if(hash == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureMethodKeyMismatch")); 

            int signatureLength; 
            if (m_signature.SignedInfo.SignatureLength == null)
                signatureLength = hash.HashSize;
            else
                signatureLength = Convert.ToInt32(m_signature.SignedInfo.SignatureLength, null); 
            // signatureLength should be less than hash size
            if (signatureLength < 0 || signatureLength > hash.HashSize) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength")); 
            if (signatureLength % 8 != 0)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength2")); 

            BuildDigestedReferences();
            switch (hash.HashName) {
            case "SHA1": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigHMACSHA1Url;
                break; 
            case "SHA256": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA256Url;
                break; 
            case "SHA384":
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA384Url;
                break;
            case "SHA512": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACSHA512Url;
                break; 
            case "MD5": 
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACMD5Url;
                break; 
            case "RIPEMD160":
                SignedInfo.SignatureMethod = SignedXml.XmlDsigMoreHMACRIPEMD160Url;
                break;
            default: 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureMethodKeyMismatch"));
            } 
 
            byte[] hashValue = GetC14NDigest(hash);
            m_signature.SignatureValue = new byte[signatureLength / 8]; 
            Buffer.BlockCopy(hashValue, 0, m_signature.SignatureValue, 0, signatureLength / 8);
        }

        // 
        // virtual methods
        // 
 
        protected virtual AsymmetricAlgorithm GetPublicKey() {
            if (KeyInfo == null) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_KeyInfoRequired"));

            if (m_x509Enum != null) {
                AsymmetricAlgorithm key = GetNextCertificatePublicKey(); 
                if (key != null)
                    return key; 
            } 

            if (m_keyInfoEnum == null) 
                m_keyInfoEnum = KeyInfo.GetEnumerator();

            // In our implementation, we move to the next KeyInfo clause which is an RSAKeyValue, DSAKeyValue or KeyInfoX509Data
            while (m_keyInfoEnum.MoveNext()) { 
                RSAKeyValue rsaKeyValue = m_keyInfoEnum.Current as RSAKeyValue;
                if (rsaKeyValue != null) 
                    return rsaKeyValue.Key; 

                DSAKeyValue dsaKeyValue = m_keyInfoEnum.Current as DSAKeyValue; 
                if (dsaKeyValue != null)
                    return dsaKeyValue.Key;

                KeyInfoX509Data x509Data = m_keyInfoEnum.Current as KeyInfoX509Data; 
                if (x509Data != null) {
                    m_x509Collection = Utils.BuildBagOfCerts (x509Data, CertUsageType.Verification); 
                    if (m_x509Collection.Count > 0) { 
                        m_x509Enum = m_x509Collection.GetEnumerator();
                        AsymmetricAlgorithm key = GetNextCertificatePublicKey(); 
                        if (key != null)
                            return key;
                    }
                } 
            }
 
            return null; 
        }
 
        private X509Certificate2Collection BuildBagOfCerts () {
            X509Certificate2Collection collection = new X509Certificate2Collection();
            if (this.KeyInfo != null) {
                foreach (KeyInfoClause clause in this.KeyInfo) { 
                    KeyInfoX509Data x509Data = clause as KeyInfoX509Data;
                    if (x509Data != null) 
                        collection.AddRange(Utils.BuildBagOfCerts(x509Data, CertUsageType.Verification)); 
                }
            } 

            return collection;
        }
 
        private AsymmetricAlgorithm GetNextCertificatePublicKey () {
            while (m_x509Enum.MoveNext()) { 
                X509Certificate2 certificate = (X509Certificate2) m_x509Enum.Current; 
                if (certificate != null)
                    return certificate.PublicKey.Key; 
            }

            return null;
        } 

        public virtual XmlElement GetIdElement (XmlDocument document, string idValue) { 
            if (document == null) 
                return null;
 
            // Get the element with idValue
            XmlElement elem = document.GetElementById(idValue);
            if (elem != null)
                return elem; 
            elem = document.SelectSingleNode("//*[@Id=\"" + idValue + "\"]") as XmlElement;
            if (elem != null) 
                return elem; 
            elem = document.SelectSingleNode("//*[@id=\"" + idValue + "\"]") as XmlElement;
            if (elem != null) 
                return elem;
            elem = document.SelectSingleNode("//*[@ID=\"" + idValue + "\"]") as XmlElement;

            return elem; 
        }
 
        // 
        // private methods
        // 

        private bool bCacheValid = false;
        private byte[] _digestedSignedInfo = null;
 
        private byte[] GetC14NDigest (HashAlgorithm hash) {
            if (!bCacheValid || !this.SignedInfo.CacheValid) { 
                string baseUri = (m_containingDocument == null ? null : m_containingDocument.BaseURI); 
                XmlResolver resolver = (m_bResolverSet ? m_xmlResolver : new XmlSecureResolver(new XmlUrlResolver(), baseUri));
                XmlDocument doc = Utils.PreProcessElementInput(SignedInfo.GetXml(), resolver, baseUri); 
                // Add non default namespaces in scope
                CanonicalXmlNodeList namespaces = (m_context == null ? null : Utils.GetPropagatedAttributes(m_context));
                Utils.AddNamespaces(doc.DocumentElement, namespaces);
                Transform c14nMethodTransform = SignedInfo.CanonicalizationMethodObject; 
                c14nMethodTransform.Resolver = resolver;
                c14nMethodTransform.BaseURI = baseUri; 
                c14nMethodTransform.LoadInput(doc); 
                _digestedSignedInfo = c14nMethodTransform.GetDigestedOutput(hash);
                bCacheValid = true; 
            }
            return _digestedSignedInfo;
        }
 
        private int GetReferenceLevel (int index, ArrayList references) {
            if (m_refProcessed[index]) return m_refLevelCache[index]; 
            m_refProcessed[index] = true; 
            Reference reference = (Reference) references[index];
            if (reference.Uri == null || reference.Uri.Length == 0 || (reference.Uri.Length > 0 && reference.Uri[0] != '#')) { 
                m_refLevelCache[index] = 0;
                return 0;
            }
            if (reference.Uri.Length > 0 && reference.Uri[0] == '#') { 
                String idref = Utils.ExtractIdFromLocalUri(reference.Uri);
                if (idref == "xpointer(/)") { 
                    m_refLevelCache[index] = 0; 
                    return 0;
                } 
                // If this is pointing to another reference
                for (int j=0; j < references.Count; ++j) {
                    if (((Reference)references[j]).Id == idref) {
                        m_refLevelCache[index] = GetReferenceLevel(j, references) + 1; 
                        return (m_refLevelCache[index]);
                    } 
                } 
                // Then the reference points to an object tag
                m_refLevelCache[index] = 0; 
                return 0;
            }
            // Malformed reference
            throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidReference")); 
        }
 
        private class ReferenceLevelSortOrder : IComparer { 
            private ArrayList m_references = null;
            public ReferenceLevelSortOrder() {} 

            public ArrayList References {
                get { return m_references; }
                set { m_references = value; } 
            }
 
            public int Compare(Object a, Object b) { 
                Reference referenceA = a as Reference;
                Reference referenceB = b as Reference; 

                // Get the indexes
                int iIndexA = 0;
                int iIndexB = 0; 
                int i = 0;
                foreach (Reference reference in References) { 
                    if (reference == referenceA) iIndexA = i; 
                    if (reference == referenceB) iIndexB = i;
                    i++; 
                }

                int iLevelA = referenceA.SignedXml.GetReferenceLevel(iIndexA, References);
                int iLevelB = referenceB.SignedXml.GetReferenceLevel(iIndexB, References); 
                return iLevelA.CompareTo(iLevelB);
            } 
        } 

        private void BuildDigestedReferences() { 
            // Default the DigestMethod and Canonicalization
            ArrayList references = SignedInfo.References;
            // Reset the cache
            m_refProcessed = new bool[references.Count]; 
            m_refLevelCache = new int[references.Count];
 
            ReferenceLevelSortOrder sortOrder = new ReferenceLevelSortOrder(); 
            sortOrder.References = references;
            // Don't alter the order of the references array list 
            ArrayList sortedReferences = new ArrayList();
            foreach (Reference reference in references) {
                sortedReferences.Add(reference);
            } 
            sortedReferences.Sort(sortOrder);
 
            CanonicalXmlNodeList nodeList = new CanonicalXmlNodeList(); 
            foreach (DataObject obj in m_signature.ObjectList) {
                nodeList.Add(obj.GetXml()); 
            }
            foreach (Reference reference in sortedReferences) {
                // If no DigestMethod has yet been set, default it to sha1
                if (reference.DigestMethod == null) 
                    reference.DigestMethod = XmlDsigSHA1Url;
                reference.UpdateHashValue(m_containingDocument, nodeList); 
                // If this reference has an Id attribute, add it 
                if (reference.Id != null)
                    nodeList.Add(reference.GetXml()); 
            }
        }

        private bool CheckDigestedReferences () { 
            ArrayList references = m_signature.SignedInfo.References;
            for (int i = 0; i < references.Count; ++i) { 
                Reference digestedReference = (Reference) references[i]; 
                byte[] calculatedHash = digestedReference.CalculateHashValue(m_containingDocument, m_signature.ReferencedItems);
 
                // Compare both hashes
                if (calculatedHash.Length != digestedReference.DigestValue.Length)
                    return false;
 
                byte[] rgb1 = calculatedHash;
                byte[] rgb2 = digestedReference.DigestValue; 
                for (int j = 0; j < rgb1.Length; ++j) { 
                    if (rgb1[j] != rgb2[j]) return false;
                } 
            }
            return true;
        }
 
        private bool CheckSignedInfo (AsymmetricAlgorithm key) {
            if (key == null) 
                throw new ArgumentNullException("key"); 

            SignatureDescription signatureDescription = CryptoConfig.CreateFromName(SignatureMethod) as SignatureDescription; 
            if (signatureDescription == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureDescriptionNotCreated"));

            // Let's see if the key corresponds with the SignatureMethod 
            Type ta = Type.GetType(signatureDescription.KeyAlgorithm);
            Type tb = key.GetType(); 
            if ((ta != tb) && !ta.IsSubclassOf(tb) && !tb.IsSubclassOf(ta)) 
                // Signature method key mismatch
                return false; 

            HashAlgorithm hashAlgorithm = signatureDescription.CreateDigest();
            if (hashAlgorithm == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_CreateHashAlgorithmFailed")); 
            byte[] hashval = GetC14NDigest(hashAlgorithm);
 
            AsymmetricSignatureDeformatter asymmetricSignatureDeformatter = signatureDescription.CreateDeformatter(key); 
            return asymmetricSignatureDeformatter.VerifySignature(hashval, m_signature.SignatureValue);
        } 

        private bool CheckSignedInfo (KeyedHashAlgorithm macAlg) {
            if (macAlg == null)
                throw new ArgumentNullException("macAlg"); 

            int signatureLength; 
            if (m_signature.SignedInfo.SignatureLength == null) 
                signatureLength = macAlg.HashSize;
            else 
                signatureLength = Convert.ToInt32(m_signature.SignedInfo.SignatureLength, null);

            // signatureLength should be less than hash size
            if (signatureLength < 0 || signatureLength > macAlg.HashSize) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength"));
            if (signatureLength % 8 != 0) 
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength2")); 
            if (m_signature.SignatureValue == null)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_SignatureValueRequired")); 
            if (m_signature.SignatureValue.Length != signatureLength / 8)
                throw new CryptographicException(SecurityResources.GetResourceString("Cryptography_Xml_InvalidSignatureLength"));

            // Calculate the hash 
            byte[] hashValue = GetC14NDigest(macAlg);
            for (int i=0; i

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