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//------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//------------------------------------------------------------
using System.Security.Cryptography.X509Certificates;
namespace System.IdentityModel.Tokens
{
/// <summary>
/// This class defines the encrypted key encrypting credentials. They are usually used
/// as data encrypting credentials to encrypt things like token.
/// </summary>
public class EncryptedKeyEncryptingCredentials : EncryptingCredentials
{
EncryptingCredentials _wrappingCredentials;
byte[] _keyBytes;
/// <summary>
/// Use this constructor if user wants to use the default wrapping algorithm and encryption algorithm,
/// which are RSA-OAEP and AES256 respectively.
/// </summary>
/// <param name="certificate">The certificate used to encrypt the key.</param>
public EncryptedKeyEncryptingCredentials( X509Certificate2 certificate )
: this( new X509EncryptingCredentials( certificate ), SecurityAlgorithms.DefaultSymmetricKeyLength, SecurityAlgorithms.DefaultEncryptionAlgorithm )
{
}
/// <summary>
/// Use this contructor if users want to supply their own wrapping algorithm and encryption algorithm
/// and wrapping credentials is x509 certificate.
/// </summary>
/// <param name="certificate">The certificate used to encrypt the session key.</param>
/// <param name="keyWrappingAlgorithm">The key wrapping algorithm. This should be asymmetric algorithm.</param>
/// <param name="keySizeInBits">The key size of the wrapped session key.</param>
/// <param name="encryptionAlgorithm">The encryption algorithm when session key is used. This should be symmetric key algorithm.</param>
public EncryptedKeyEncryptingCredentials( X509Certificate2 certificate, string keyWrappingAlgorithm, int keySizeInBits, string encryptionAlgorithm )
: this( new X509EncryptingCredentials( certificate, keyWrappingAlgorithm ), keySizeInBits, encryptionAlgorithm )
{
}
/// <summary>
/// Use this constructor if users already have an encryting credentials and want to use that as a wrapping credentials.
/// </summary>
/// <param name="wrappingCredentials">The key wrapping credentials used to encrypt the session key.</param>
/// <param name="keySizeInBits">The key size of the wrapped session key.</param>
/// <param name="encryptionAlgorithm">The encryption algorithm when session key is used. This should be symmetric key algorithm.</param>
/// <exception cref="ArgumentNullException">When the wrappingCredentials is null.</exception>
public EncryptedKeyEncryptingCredentials( EncryptingCredentials wrappingCredentials, int keySizeInBits, string encryptionAlgorithm )
{
if ( wrappingCredentials == null )
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull( "wrappingCredentials" );
}
//
// Key materials
//
if ( encryptionAlgorithm == SecurityAlgorithms.DesEncryption ||
encryptionAlgorithm == SecurityAlgorithms.TripleDesEncryption ||
encryptionAlgorithm == SecurityAlgorithms.TripleDesKeyWrap )
{
_keyBytes = CryptoHelper.KeyGenerator.GenerateDESKey( keySizeInBits );
}
else
{
_keyBytes = CryptoHelper.KeyGenerator.GenerateSymmetricKey( keySizeInBits );
}
base.SecurityKey = new InMemorySymmetricSecurityKey( _keyBytes );
//
// Wrapping key
//
_wrappingCredentials = wrappingCredentials;
//
// key identifier
//
byte[] encryptedKey = _wrappingCredentials.SecurityKey.EncryptKey( _wrappingCredentials.Algorithm, _keyBytes );
base.SecurityKeyIdentifier = new SecurityKeyIdentifier( new EncryptedKeyIdentifierClause( encryptedKey, _wrappingCredentials.Algorithm, _wrappingCredentials.SecurityKeyIdentifier ) );
//
// encryption algorithm
//
base.Algorithm = encryptionAlgorithm;
}
/// <summary>
/// Gets the key wrapping credentials used to encrypt the session key, for example,
/// X509EncryptingCredentials.
/// </summary>
public EncryptingCredentials WrappingCredentials
{
get
{
return _wrappingCredentials;
}
}
}
}
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