/// <summary>
/// Checks the validity of the stored HMAC in the packet buffer.
/// </summary>
/// <param name="packetData">The packet the way it was received.</param>
/// <returns>A boolean that indicates if the stored HMAC is whether or not valid.</returns>
public bool VerifyHmac(byte[] packetData)
{
byte[] storedHmac = Sequence.ReadBlock(packetData, packetData.Length - 10, 10);
byte[] authData = Sequence.ReadBlock(packetData, 2, packetData.Length - 10 - 2);
byte[] expectedHmac = MD5Hmac.ComputeHMAC(authData, HmacKey, 10);
return(storedHmac.SequenceEqual(expectedHmac));
}
/// <summary>
/// Computes the HMAC for the specified packet data.
/// </summary>
/// <param name="authData"> The whole packet buffer, except for the size and the own HMAC.</param>
/// <returns>The HMAC of the packet, which, in the case of Grand Chase, has the size of 10 bytes.</returns>
public byte[] GetHmac(byte[] authData)
{
return(MD5Hmac.ComputeHMAC(authData, HmacKey, 10));
}
/// <summary>
/// Computes the HMAC for the specified packet data.
/// </summary>
/// <param name="partialBuffer">The whole packet buffer, except for the own HMAC.</param>
/// <returns>The HMAC.</returns>
public byte[] GetHmac(byte[] partialBuffer)
{
byte[] authData = Sequence.ReadBlock(partialBuffer, 2, partialBuffer.Length - 2);
return(MD5Hmac.ComputeHmac(authData, HmacKey, 10));
}