/// <summary>
/// Writes a <see cref="EncryptedSecurityToken"/> using the xmlWriter.
/// </summary>
/// <param name="writer">The XmlWriter to which the encrypted token is written.</param>
/// <param name="token">The <see cref="SecurityToken"/> which must be an instance of <see cref="EncryptedSecurityToken"/>.</param>
/// <exception cref="ArgumentNullException">The input prameter 'writer' is null.</exception>
/// <exception cref="ArgumentNullException">The input prameter 'token' is null.</exception>
/// <exception cref="ArgumentException">The <see cref="SecurityToken"/> is not an instance of <see cref="EncryptedSecurityToken"/>.</exception>
/// <exception cref="InvalidOperationException">The property 'Configuration' is null. This property is required for obtaining keys for encryption.</exception>
/// <exception cref="InvalidOperationException">The ContaingCollection was unable to find a <see cref="SecurityTokenHandler"/> that is able to write
/// the <see cref="SecurityToken"/> returned by 'EncryptedSecurityToken.Token'.</exception>
/// <exception cref="SecurityTokenException">The property 'EncryptinCredentials.SecurityKey is not a <see cref="SymmetricSecurityKey"/></exception>
public override void WriteToken(XmlWriter writer, SecurityToken token)
{
if (null == writer)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("writer");
}
if (null == token)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("token");
}
EncryptedSecurityToken encryptedToken = token as EncryptedSecurityToken;
if (null == encryptedToken)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument("token", SR.GetString(SR.ID4024));
}
if (this.ContainingCollection == null)
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID4279));
}
//
// This implementation simply wraps the token in xenc:EncryptedData
//
EncryptedDataElement encryptedData = new EncryptedDataElement(KeyInfoSerializer);
using (MemoryStream plaintextStream = new MemoryStream())
{
//
// Buffer the plaintext
//
using (XmlDictionaryWriter plaintextWriter = XmlDictionaryWriter.CreateTextWriter(plaintextStream, Encoding.UTF8, false))
{
SecurityTokenHandler securityTokenHandler = this.ContainingCollection[encryptedToken.Token.GetType()];
if (securityTokenHandler != null)
{
securityTokenHandler.WriteToken(plaintextWriter, encryptedToken.Token);
}
else
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID4224, encryptedToken.Token.GetType()));
}
}
//
// Set up the EncryptedData element
//
EncryptingCredentials encryptingCredentials = encryptedToken.EncryptingCredentials;
encryptedData.Type = XmlEncryptionConstants.EncryptedDataTypes.Element;
encryptedData.KeyIdentifier = encryptingCredentials.SecurityKeyIdentifier;
encryptedData.Algorithm = encryptingCredentials.Algorithm;
//
// Get the encryption key, which must be symmetric
//
SymmetricSecurityKey encryptingKey = encryptingCredentials.SecurityKey as SymmetricSecurityKey;
if (encryptingKey == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new SecurityTokenException(SR.GetString(SR.ID3064)));
}
//
// Do the actual encryption
//
using (SymmetricAlgorithm symmetricAlgorithm = encryptingKey.GetSymmetricAlgorithm(encryptingCredentials.Algorithm))
{
byte[] plainTextBytes = plaintextStream.GetBuffer();
DebugEncryptedTokenClearText(plainTextBytes, Encoding.UTF8);
encryptedData.Encrypt(symmetricAlgorithm, plainTextBytes, 0, (int)plaintextStream.Length);
}
}
//
// Write the EncryptedData element
//
encryptedData.WriteXml(writer, KeyInfoSerializer);
}
/// <summary>
/// Reads the encrypted security token.
/// </summary>
/// <param name="reader">The reader from which to read the token.</param>
/// <returns>An instance of <see cref="SecurityToken"/>.</returns>
/// <exception cref="ArgumentNullException">Input parameter 'reader' is null.</exception>
/// <exception cref="InvalidOperationException">One of the properties 'Configuration' or 'Configuration.ServiceTokenResolver' is null. This property is required for obtaining keys for decryption.</exception>
/// <exception cref="SecurityTokenException">A <see cref="SecurityKeyIdentifier"/> is not found inside the xml pointed to by the reader.</exception>
/// <exception cref="EncryptedTokenDecryptionFailedException">The <see cref="SecurityKeyIdentifier"/> found inside the xml cannot be resolved by Configuration.ServiceTokenResolver to a <see cref="SecurityKey"/>.</exception>
/// <exception cref="SecurityTokenException">The <see cref="SecurityKeyIdentifier"/> is not a <see cref="SymmetricSecurityKey"/>.</exception>
/// <exception cref="InvalidOperationException">The ContainingCollection (<see cref="SecurityTokenHandlerCollection"/>) is unable to find a <see cref="SecurityTokenHandler"/> that is able to read the decrypted xml and return a <see cref="SecurityToken"/>.</exception>
public override SecurityToken ReadToken(XmlReader reader)
{
if (null == reader)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("reader");
}
if (this.Configuration == null)
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID4274));
}
if (this.Configuration.ServiceTokenResolver == null)
{
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID4276));
}
//
// Read the encrypted data element
//
EncryptedDataElement encryptedData = new EncryptedDataElement(KeyInfoSerializer);
encryptedData.ReadXml(XmlDictionaryReader.CreateDictionaryReader(reader));
//
// All the clauses in a keyinfo must identify the same key, so we
// can try each clause in turn and stop when one resolves.
//
SecurityKey decryptionKey = null;
foreach (SecurityKeyIdentifierClause clause in encryptedData.KeyIdentifier)
{
this.Configuration.ServiceTokenResolver.TryResolveSecurityKey(clause, out decryptionKey);
if (null != decryptionKey)
{
break;
}
}
//
// Try to use the SKI to create the key instead.
//
if (decryptionKey == null && encryptedData.KeyIdentifier.CanCreateKey)
{
decryptionKey = encryptedData.KeyIdentifier.CreateKey();
}
//
// Fail if none of the clauses resolved or ski itself cannot create key.
//
if (null == decryptionKey)
{
EncryptedKeyIdentifierClause encryptedKeyClause;
if (encryptedData.KeyIdentifier.TryFind <EncryptedKeyIdentifierClause>(out encryptedKeyClause))
{
//
// System.IdentityModel.Tokens.EncryptedKeyIdentifierClause.ToString() does not print out
// very good information except the cipher data in this case. We have worked around that
// by using the token serializer to serialize the key identifier clause again.
//
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
new EncryptedTokenDecryptionFailedException(
SR.GetString(SR.ID4036, XmlUtil.SerializeSecurityKeyIdentifier(encryptedData.KeyIdentifier, base.ContainingCollection.KeyInfoSerializer))));
}
else
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
new EncryptedTokenDecryptionFailedException(SR.GetString(SR.ID4036, encryptedData.KeyIdentifier.ToString())));
}
}
//
// Need a symmetric key
//
SymmetricSecurityKey symmetricKey = decryptionKey as SymmetricSecurityKey;
if (null == symmetricKey)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
new SecurityTokenException(SR.GetString(SR.ID4023)));
}
//
// Do the actual decryption
//
byte[] plainText;
using (SymmetricAlgorithm decrypter = symmetricKey.GetSymmetricAlgorithm(encryptedData.Algorithm))
{
plainText = encryptedData.Decrypt(decrypter);
}
DebugEncryptedTokenClearText(plainText, Encoding.UTF8);
//
// Read and return the plaintext token
//
using (XmlReader innerTokenReader = XmlDictionaryReader.CreateTextReader(plainText, XmlDictionaryReaderQuotas.Max))
{
if (this.ContainingCollection != null && this.ContainingCollection.CanReadToken(innerTokenReader))
{
return(this.ContainingCollection.ReadToken(innerTokenReader));
}
throw DiagnosticUtility.ThrowHelperInvalidOperation(SR.GetString(SR.ID4014, innerTokenReader.LocalName, innerTokenReader.NamespaceURI));
}
}