public byte[] HandleRequest(byte[] kmsRequestData)
{
KMSV5Request kmsv5Request = CreateKMSV5Request(kmsRequestData);
byte[] decrypted = DecryptV5(kmsv5Request);
byte[] decryptedSalt = decrypted.Take(16).ToArray();
byte[] decryptedRequest = decrypted.Skip(16).ToArray();
byte[] responseBytes = Server.ExecuteKMSServerLogic(decryptedRequest, Logger);
byte[] randomSalt = Guid.NewGuid().ToByteArray();
byte[] randomSaltHash = GetSHA265Hash(randomSalt);
byte[] randomStuff = new byte[16];
for (int i = 0; i < 16; i++)
{
randomStuff[i] = (byte)(decryptedSalt[i] ^ kmsv5Request.Salt[i] ^ randomSalt[i]);
}
byte[] responsedata = responseBytes.Concat(randomStuff).Concat(randomSaltHash).ToArray();
byte[] encryptedResponseData = EncryptV5(responsedata, kmsv5Request.Salt);
KMSV5Response kmsResponse = new KMSV5Response {
Version = kmsv5Request.Version, Salt = kmsv5Request.Salt, Encrypted = encryptedResponseData
};
byte[] encryptedResponse = CreateKMSV5ResponseBytes(kmsResponse);
return(encryptedResponse);
}
private static KMSV5Request CreateKMSV5Request(byte[] kmsRequestData)
{
KMSV5Request kmsRequest = new KMSV5Request();
using (MemoryStream stream = new MemoryStream(kmsRequestData))
{
using BinaryReader binaryReader = new BinaryReader(stream);
kmsRequest.BodyLength1 = binaryReader.ReadUInt32();
kmsRequest.BodyLength2 = binaryReader.ReadUInt32();
kmsRequest.Version = binaryReader.ReadUInt32();
kmsRequest.Salt = binaryReader.ReadBytes(16);
kmsRequest.EncryptedRequest = binaryReader.ReadBytes(kmsRequestData.Length - 8 - 4 - 16 - 4);
kmsRequest.Pad = binaryReader.ReadBytes(4);
}
return(kmsRequest);
}
private static byte[] DecryptV5(KMSV5Request kmsRequest)
{
byte[] iv = kmsRequest.Salt;
byte[] encrypted =
kmsRequest.Salt.Concat(kmsRequest.EncryptedRequest)
.Concat(kmsRequest.Pad).ToArray();
RijndaelManaged rijndaelManaged = new RijndaelManaged {
Key = Key, IV = iv
};
byte[] decrypted;
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, rijndaelManaged.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(encrypted, 0, encrypted.Length);
}
decrypted = ms.ToArray();
}
return(decrypted);
}
