public EncryptedMessage(byte[] authKey, byte[] plainData)
{
_authKey = authKey;
using (var ms = new MemoryStream(plainData))
{
using (var br = new BinaryReader(ms))
{
AuthKeyId = br.ReadInt64();
MsgKey = new BigInteger(br.ReadBytes(16));
// дешифруем эту дату
byte[] aesKey = CalculateAesKey(8, MsgKey.GetBytes());
byte[] aesIv = CalculateIV(8, MsgKey.GetBytes());
var aesIge = new Aes256IgeManaged(aesKey, aesIv);
Data = new EncryptedData(aesIge.Decrypt(br.ReadBytes(plainData.Length - 8 - 16)));
}
}
}
/// <summary>
/// Создание вектора AES
/// </summary>
/// <param name="newNonce"></param>
/// <param name="serverNonce"></param>
/// <returns></returns>
private byte[] CalculateTmpAesIV(BigInteger newNonce, BigInteger serverNonce)
{
//tmp_aes_iv := substr (SHA1(server_nonce + new_nonce), 12, 8) + SHA1(new_nonce + new_nonce) + substr (new_nonce, 0, 4);
using (var ms = new MemoryStream())
using (var bw = new BinaryWriter(ms))
{
SHA1 sha1 = SHA1.Create();
bw.Write(serverNonce.GetBytes());
bw.Write(newNonce.GetBytes());
byte[] hash1 = sha1.ComputeHash(ms.ToArray());
ms.SetLength(0);
bw.Write(newNonce.GetBytes());
bw.Write(newNonce.GetBytes());
byte[] hash2 = sha1.ComputeHash(ms.ToArray());
ms.SetLength(0);
bw.Write(hash1, 12, 8);
bw.Write(hash2);
bw.Write(newNonce.GetBytes(), 0, 4);
return ms.ToArray();
}
}
/// <summary>
/// Создание ключа AES
/// </summary>
/// <returns></returns>
private byte[] CalculateTmpAesKey(BigInteger newNonce, BigInteger serverNonce)
{
//tmp_aes_key := SHA1(new_nonce + server_nonce) + substr (SHA1(server_nonce + new_nonce), 0, 12);
using (var ms = new MemoryStream())
using (var bw = new BinaryWriter(ms))
{
SHA1 sha1 = SHA1.Create();
bw.Write(newNonce.GetBytes());
bw.Write(serverNonce.GetBytes());
byte[] sumSha = sha1.ComputeHash(ms.ToArray());
ms.SetLength(0);
bw.Write(serverNonce.GetBytes());
bw.Write(newNonce.GetBytes());
byte[] reverseSumSha = sha1.ComputeHash(ms.ToArray());
ms.SetLength(0);
bw.Write(sumSha);
bw.Write(reverseSumSha, 0, 12);
return ms.ToArray();
}
}
/// <summary>
/// Формирование соли по схеме substr(new_nonce, 0, 8) XOR substr(server_nonce, 0, 8)
/// </summary>
/// <param name="newNonce"></param>
/// <param name="serverNonce"></param>
/// <returns></returns>
private long CalculateInitialSalt(BigInteger newNonce, BigInteger serverNonce)
{
var nn = new byte[8];
var sn = new byte[8];
Array.Copy(newNonce.GetBytes(), nn, 8);
Array.Copy(serverNonce.GetBytes(), sn, 8);
return BitConverter.ToInt32(Aes256IgeManaged.XOR(nn, sn), 0);
}