public Protocol Authenticate(string username, string password)
{
/* Number of authentication tries. */
int tries = 3;
/* Set username and password. */
this._username = Encoding.UTF8.GetBytes(username);
this._password = Encoding.UTF8.GetBytes(password);
while (true)
{
/* Connect to a spotify server. */
this._protocol.Connect();
/* Send and receive initial packets. */
try
{
this._protocol.SendInitialPacket();
this._protocol.ReceiveInitialPacket();
break;
}
catch (ProtocolException e)
{
if (tries-- > 0)
{
continue;
}
throw new AuthenticationException(e);
}
}
/* Generate auth hash. */
this.GenerateAuthHash();
/* Compute shared key (Diffie Hellman key exchange). */
this._dhSharedKey = DH.ComputeSharedKey(this._dhClientKeyPair.PrivateKey, this._dhServerPublicKey);
/* Prepare a message to authenticate. */
ByteBuffer buffer = ByteBuffer.Allocate(((this._authHash.Length + this._clientRandom.Length) + this._serverRandom.Length) + 1);
/* Append auth hash, client and server random to message. */
buffer.Put(this._authHash);
buffer.Put(this._clientRandom);
buffer.Put(this._serverRandom);
buffer.Put((byte)0x00); /* Changed later */
buffer.Flip();
/* Get message bytes and allocate space for HMACs. */
byte[] bytes = new byte[buffer.Remaining];
byte[] hmac = new byte[5 * 20];
int offset = 0;
buffer.Get(bytes);
/* Run HMAC SHA-1 over message. 5 times. */
for (int i = 1; i <= 5; i++)
{
/* Change last byte (53) of message. */
bytes[bytes.Length - 1] = (byte)i;
/* Compute HMAC SHA-1 using the shared key. */
Hash.HmacSha1(bytes, this._dhSharedKey, hmac, offset);
/* Overwrite first 20 bytes of message with output from this round. */
for (int j = 0; j < 20; j++)
{
bytes[j] = hmac[offset + j];
}
/* Advance to next position. */
offset += 20;
}
/* Use field of HMACs to setup keys for Shannon stream cipher (key length: 32). */
Array.Copy(hmac, 20, this._keySend, 0, 32);
Array.Copy(hmac, 52, this._keyRecv, 0, 32);
/* Set stream cipher keys. */
this._shannonSend.key(this._keySend);
this._shannonRecv.key(this._keyRecv);
/*
* First 20 bytes of HMAC output is used to key another HMAC computed
* for the second authentication packet send by the client.
*/
Array.Copy(hmac, 0, this._keyHmac, 0, 20);
/* Solve puzzle */
this.SolvePuzzle();
/* Generate HMAC */
this.GenerateAuthHmac();
try
{
this._protocol.SendAuthenticationPacket();
this._protocol.ReceiveAuthenticationPacket();
}
catch (ProtocolException e)
{
throw new AuthenticationException(e);
}
return(this._protocol);
}
