protected override void StartReNegotiation()
{
try
{
switch (_version)
{
case 3:
ProtocolV4(_baseStream, _clientCredentials, _trustedRootCertificates, _manager, _preSharedKey, _supportedOptions);
break;
default:
throw new SecureChannelException(SecureChannelCode.ProtocolVersionNotSupported, _remotePeerEP, _remotePeerCert, "SecureChannel protocol version '" + _version + "' not supported.");
}
}
catch (SecureChannelException ex)
{
try
{
SecureChannelPacket.WritePacket(_baseStream, ex.Code);
}
catch
{ }
throw;
}
}
public SecureChannelClientStream(Stream stream, IPEndPoint remotePeerEP, CertificateStore clientCredentials, Certificate[] trustedRootCertificates, ISecureChannelSecurityManager manager, SecureChannelCryptoOptionFlags supportedOptions, int reNegotiateOnBytesSent, int reNegotiateAfterSeconds, string preSharedKey = null)
: base(remotePeerEP, reNegotiateOnBytesSent, reNegotiateAfterSeconds)
{
_clientCredentials = clientCredentials;
_trustedRootCertificates = trustedRootCertificates;
_manager = manager;
_supportedOptions = supportedOptions;
_preSharedKey = preSharedKey;
try
{
//read server protocol version
_version = stream.ReadByte();
switch (_version)
{
case 4:
//send supported client version
stream.WriteByte(4);
ProtocolV4(stream, clientCredentials, trustedRootCertificates, manager, preSharedKey, supportedOptions);
break;
default:
throw new SecureChannelException(SecureChannelCode.ProtocolVersionNotSupported, _remotePeerEP, _remotePeerCert, "SecureChannel protocol version '" + _version + "' not supported.");
}
}
catch (SecureChannelException ex)
{
try
{
if (_baseStream == null)
{
SecureChannelPacket.WritePacket(stream, ex.Code);
}
else
{
SecureChannelPacket.WritePacket(this, ex.Code);
}
}
catch
{ }
throw new SecureChannelException(ex.Code, _remotePeerEP, _remotePeerCert, ex.Message, ex.InnerException);
}
}
private void ProtocolV4(Stream stream, CertificateStore clientCredentials, Certificate[] trustedRootCertificates, ISecureChannelSecurityManager manager, string preSharedKey, SecureChannelCryptoOptionFlags supportedOptions)
{
#region 1. hello handshake
//send client hello
SecureChannelPacket.Hello clientHello = new SecureChannelPacket.Hello(BinaryID.GenerateRandomID256(), supportedOptions);
SecureChannelPacket.WritePacket(stream, clientHello);
//read server hello
SecureChannelPacket.Hello serverHello = (new SecureChannelPacket(stream)).GetHello();
//read selected crypto option
_selectedCryptoOption = supportedOptions & serverHello.CryptoOptions;
if (_selectedCryptoOption == SecureChannelCryptoOptionFlags.None)
{
throw new SecureChannelException(SecureChannelCode.NoMatchingCryptoAvailable, _remotePeerEP, _remotePeerCert);
}
#endregion
#region 2. key exchange
//read server key exchange data
SecureChannelPacket.KeyExchange serverKeyExchange = (new SecureChannelPacket(stream)).GetKeyExchange();
SymmetricEncryptionAlgorithm encAlgo;
string hashAlgo;
KeyAgreement keyAgreement;
switch (_selectedCryptoOption)
{
case SecureChannelCryptoOptionFlags.DHE2048_RSA_WITH_AES256_CBC_HMAC_SHA256:
encAlgo = SymmetricEncryptionAlgorithm.Rijndael;
hashAlgo = "SHA256";
keyAgreement = new DiffieHellman(DiffieHellmanGroupType.RFC3526, 2048, KeyAgreementKeyDerivationFunction.Hmac, KeyAgreementKeyDerivationHashAlgorithm.SHA256);
break;
case SecureChannelCryptoOptionFlags.ECDHE256_RSA_WITH_AES256_CBC_HMAC_SHA256:
encAlgo = SymmetricEncryptionAlgorithm.Rijndael;
hashAlgo = "SHA256";
keyAgreement = new TechnitiumLibrary.Security.Cryptography.ECDiffieHellman(256, KeyAgreementKeyDerivationFunction.Hmac, KeyAgreementKeyDerivationHashAlgorithm.SHA256);
break;
default:
throw new SecureChannelException(SecureChannelCode.NoMatchingCryptoAvailable, _remotePeerEP, _remotePeerCert);
}
//send client key exchange data
SecureChannelPacket.KeyExchange clientKeyExchange = new SecureChannelPacket.KeyExchange(keyAgreement.GetPublicKeyXML(), clientCredentials.PrivateKey, hashAlgo);
SecureChannelPacket.WritePacket(stream, clientKeyExchange);
//generate master key
byte[] masterKey = GenerateMasterKey(clientHello, serverHello, _preSharedKey, keyAgreement, serverKeyExchange.PublicKeyXML);
//verify master key using HMAC authentication
{
SecureChannelPacket.Authentication clientAuthentication = new SecureChannelPacket.Authentication(serverHello, masterKey);
SecureChannelPacket.WritePacket(stream, clientAuthentication);
SecureChannelPacket.Authentication serverAuthentication = (new SecureChannelPacket(stream)).GetAuthentication();
if (!serverAuthentication.IsValid(clientHello, masterKey))
{
throw new SecureChannelException(SecureChannelCode.ProtocolAuthenticationFailed, _remotePeerEP, _remotePeerCert);
}
}
//enable channel encryption
switch (encAlgo)
{
case SymmetricEncryptionAlgorithm.Rijndael:
//using MD5 for generating AES IV of 128bit block size
HashAlgorithm md5Hash = HashAlgorithm.Create("MD5");
byte[] eIV = md5Hash.ComputeHash(clientHello.Nonce.ID);
byte[] dIV = md5Hash.ComputeHash(serverHello.Nonce.ID);
//create encryption and decryption objects
SymmetricCryptoKey encryptionKey = new SymmetricCryptoKey(SymmetricEncryptionAlgorithm.Rijndael, masterKey, eIV, PaddingMode.None);
SymmetricCryptoKey decryptionKey = new SymmetricCryptoKey(SymmetricEncryptionAlgorithm.Rijndael, masterKey, dIV, PaddingMode.None);
//enable encryption
EnableEncryption(stream, encryptionKey, decryptionKey, new HMACSHA256(masterKey), new HMACSHA256(masterKey));
break;
default:
throw new SecureChannelException(SecureChannelCode.NoMatchingCryptoAvailable, _remotePeerEP, _remotePeerCert);
}
//channel encryption is ON!
#endregion
#region 3. exchange & verify certificates & signatures
if (!_reNegotiating)
{
//send client certificate
SecureChannelPacket.WritePacket(this, clientCredentials.Certificate);
//read server certificate
_remotePeerCert = (new SecureChannelPacket(this)).GetCertificate();
//verify server certificate
try
{
_remotePeerCert.Verify(trustedRootCertificates);
}
catch (Exception ex)
{
throw new SecureChannelException(SecureChannelCode.InvalidRemoteCertificate, _remotePeerEP, _remotePeerCert, "Invalid remote certificate.", ex);
}
}
//verify key exchange signature
switch (_selectedCryptoOption)
{
case SecureChannelCryptoOptionFlags.DHE2048_RSA_WITH_AES256_CBC_HMAC_SHA256:
case SecureChannelCryptoOptionFlags.ECDHE256_RSA_WITH_AES256_CBC_HMAC_SHA256:
if (_remotePeerCert.PublicKeyEncryptionAlgorithm != AsymmetricEncryptionAlgorithm.RSA)
{
throw new SecureChannelException(SecureChannelCode.InvalidRemoteCertificateAlgorithm, _remotePeerEP, _remotePeerCert);
}
if (!serverKeyExchange.IsSignatureValid(_remotePeerCert, "SHA256"))
{
throw new SecureChannelException(SecureChannelCode.InvalidRemoteKeyExchangeSignature, _remotePeerEP, _remotePeerCert);
}
break;
default:
throw new SecureChannelException(SecureChannelCode.NoMatchingCryptoAvailable, _remotePeerEP, _remotePeerCert);
}
if ((manager != null) && !manager.ProceedConnection(_remotePeerCert))
{
throw new SecureChannelException(SecureChannelCode.SecurityManagerDeclinedAccess, _remotePeerEP, _remotePeerCert, "Security manager declined access.");
}
#endregion
}
protected byte[] GenerateMasterKey(SecureChannelPacket.Hello clientHello, SecureChannelPacket.Hello serverHello, string preSharedKey, KeyAgreement keyAgreement, string otherPartyPublicKeyXML)
{
using (MemoryStream mS = new MemoryStream(128))
{
clientHello.WriteTo(mS);
serverHello.WriteTo(mS);
if (string.IsNullOrEmpty(preSharedKey))
keyAgreement.HmacMessage = mS.ToArray();
else
keyAgreement.HmacMessage = (new HMACSHA256(Encoding.UTF8.GetBytes(preSharedKey))).ComputeHash(mS.ToArray());
}
return keyAgreement.DeriveKeyMaterial(otherPartyPublicKeyXML);
}
