/// <summary>
/// This method asks the server for a list of identifiers paired with method
/// names and -parameter types. This is used when invoking methods server side.
/// </summary>
protected override void SyncInterface(Type serviceType,
string username = null, string password = null)
{
if (!string.IsNullOrEmpty(username) && !string.IsNullOrEmpty(password))
{
//do zk protocol authentication
var sr = new ZkProtocol();
// Step 1. Client sends username and ephemeral hash of random number.
var aRand = sr.CryptRand();
var aClientEphemeral = sr.GetClientEphemeralA(aRand);
// send username and aClientEphemeral to server
_binWriter.Write((int)MessageType.ZkInitiate);
_binWriter.Write(username);
_binWriter.Write(aClientEphemeral); //always 32 bytes
// get response from server
var userFound = _binReader.ReadBoolean();
if (!userFound)
{
throw new InvalidCredentialException("authentication failed");
}
var salt = _binReader.ReadBytes(32);
var bServerEphemeral = _binReader.ReadBytes(32);
// Step 3. Client and server calculate random scramble of ephemeral hash values exchanged.
var clientScramble = sr.CalculateRandomScramble(aClientEphemeral, bServerEphemeral);
// Step 4. Client computes session key
var clientSessionKey = sr.ClientComputeSessionKey(salt, username, password,
aClientEphemeral, bServerEphemeral, clientScramble);
// Step 6. Client creates hash of session key and sends to server. Server creates same key and verifies.
var clientSessionHash = sr.ClientCreateSessionHash(username, salt, aClientEphemeral,
bServerEphemeral, clientSessionKey);
// send to server and server verifies
_binWriter.Write((int)MessageType.ZkProof);
_binWriter.Write(clientSessionHash); //always 32 bytes
// get response
var serverVerified = _binReader.ReadBoolean();
if (!serverVerified)
{
throw new InvalidCredentialException("authentication failed");
}
var serverSessionHash = _binReader.ReadBytes(32);
var clientServerSessionHash = sr.ServerCreateSessionHash(aClientEphemeral,
clientSessionHash, clientSessionKey);
if (!serverSessionHash.IsEqualTo(clientServerSessionHash))
{
throw new InvalidCredentialException("authentication failed");
}
_zkCrypto = new ZkCrypto(clientSessionKey, clientScramble);
}
if (!_syncInfoCache.TryGetValue(serviceType, out _syncInfo))
{
//write the message type
_binWriter.Write((int)MessageType.SyncInterface);
if (null != _zkCrypto)
{
//sync interface with encryption
var assemName = serviceType.FullName;
var assemblyNameEncrypted = _zkCrypto.Encrypt(assemName.ConvertToBytes());
_binWriter.Write(assemblyNameEncrypted.Length);
_binWriter.Write(assemblyNameEncrypted);
}
else
{
_binWriter.Write(serviceType.FullName);
}
//read sync data
var len = _binReader.ReadInt32();
//len is zero when AssemblyQualifiedName not same version or not found
#if (!NET35)
if (len == 0) throw new TypeAccessException("SyncInterface failed. Type or version of type unknown.");
#else
if (len == 0) throw new Exception("SyncInterface failed. Type or version of type unknown.");
#endif
var bytes = _binReader.ReadBytes(len);
if (null != _zkCrypto)
{
bytes = _zkCrypto.Decrypt(bytes);
}
_syncInfo = bytes.ToDeserializedObject<ServiceSyncInfo>();
_syncInfoCache.AddOrUpdate(serviceType, _syncInfo, (t, info) => _syncInfo);
}
}
public void SimpleProtocolTest()
{
var sr = new ZkProtocol();
var username = "******";
var pwd = "cc3a6a12-0e5b-47fb-ae45-3485e34582d4";
// prerequisit: generate password hash that would be stored on server
var pwdHash = sr.HashCredentials(username, pwd);
// Step 1. Client sends username and ephemeral hash of random number.
var aRand = sr.CryptRand();
var aClientEphemeral = sr.GetClientEphemeralA(aRand);
// send username and aClientEphemeral to server
// Step 2. Server looks up username, gets pwd hash, and sends client ephemeral has of params.
var bRand = sr.CryptRand();
var bServerEphemeral = sr.GetServerEphemeralB(pwdHash.Salt, pwdHash.Verifier, bRand);
// send salt and bServerEphemeral to client
var clientSalt = pwdHash.Salt;
// Step 3. Client and server calculate random scramble of ephemeral hash values exchanged.
var clientScramble = sr.CalculateRandomScramble(aClientEphemeral, bServerEphemeral);
var serverScramble = sr.CalculateRandomScramble(aClientEphemeral, bServerEphemeral);
var scrambleSame = clientScramble.IsEqualTo(serverScramble);
// Step 4. Client computes session key
var clientSessionKey = sr.ClientComputeSessionKey(clientSalt, username, pwd, aClientEphemeral, bServerEphemeral, clientScramble);
// Step 5. Server computes session key
var serverSessionKey = sr.ServerComputeSessionKey(pwdHash.Salt, pwdHash.Key, aClientEphemeral, bServerEphemeral, serverScramble);
var sessionKeysSame = clientSessionKey.IsEqualTo(serverSessionKey);
// Step 6. Client creates hash of session key and sends to server. Server creates same key and verifies.
var clientSessionHash = sr.ClientCreateSessionHash(username, pwdHash.Salt, aClientEphemeral,
bServerEphemeral, clientSessionKey);
// send to server and server verifies
// server validates clientSessionHash is same as serverClientSessionHash
var serverClientSessionHash = sr.ClientCreateSessionHash(username, pwdHash.Salt, aClientEphemeral,
bServerEphemeral, serverSessionKey);
var clientEqualToServer = clientSessionHash.IsEqualTo(serverClientSessionHash);
// Step 7. Server creates hash of session key and sends to client. Client creates same key and verifies.
var serverSessionHash = sr.ServerCreateSessionHash(aClientEphemeral, clientSessionHash, serverSessionKey);
// server sends serverSessionHash to client
// validate that serverSessionHash is same as clientServerSessionHash
var clientServerSessionHash = sr.ServerCreateSessionHash(aClientEphemeral, clientSessionHash, clientSessionKey);
var serverEqualToClient = serverSessionHash.IsEqualTo(clientServerSessionHash);
//proof
Assert.IsTrue(sessionKeysSame);
Assert.IsTrue(scrambleSame);
Assert.IsTrue(clientEqualToServer);
Assert.IsTrue(serverEqualToClient);
var data = sr.Combine(sr.CryptRand(), sr.CryptRand(), sr.CryptRand());
var crypto = new ZkCrypto(clientSessionKey, clientScramble);
var encrypted = crypto.Encrypt(data);
var decrypted = crypto.Decrypt(encrypted);
var cryptSame = data.IsEqualTo(decrypted);
Assert.IsTrue(cryptSame);
}
