public static TLString EncryptMessage(TLObject decryptedMessage, TLEncryptedChatCommon chat)
{
var random = new Random();
var key = chat.Key.Data;
var keyHash = Utils.ComputeSHA1(key);
var keyFingerprint = new TLLong(BitConverter.ToInt64(keyHash, 12));
var decryptedBytes = decryptedMessage.ToBytes();
var bytes = Combine(BitConverter.GetBytes(decryptedBytes.Length), decryptedBytes);
var sha1Hash = Utils.ComputeSHA1(bytes);
var msgKey = sha1Hash.SubArray(sha1Hash.Length - 16, 16);
var padding = (bytes.Length % 16 == 0) ? 0 : (16 - (bytes.Length % 16));
var paddingBytes = new byte[padding];
random.NextBytes(paddingBytes);
var bytesWithPadding = Combine(bytes, paddingBytes);
var x = 0;
var sha1_a = Utils.ComputeSHA1(Combine(msgKey, key.SubArray(x, 32)));
var sha1_b = Utils.ComputeSHA1(Combine(key.SubArray(32 + x, 16), msgKey, key.SubArray(48 + x, 16)));
var sha1_c = Utils.ComputeSHA1(Combine(key.SubArray(64 + x, 32), msgKey));
var sha1_d = Utils.ComputeSHA1(Combine(msgKey, key.SubArray(96 + x, 32)));
var aesKey = Combine(sha1_a.SubArray(0, 8), sha1_b.SubArray(8, 12), sha1_c.SubArray(4, 12));
var aesIV = Combine(sha1_a.SubArray(8, 12), sha1_b.SubArray(0, 8), sha1_c.SubArray(16, 4), sha1_d.SubArray(0, 8));
var encryptedBytes = Utils.AesIge(bytesWithPadding, aesKey, aesIV, true);
var resultBytes = Combine(keyFingerprint.ToBytes(), msgKey, encryptedBytes);
return(TLString.FromBigEndianData(resultBytes));
}
public static byte[] ToBytes(TLObject obj, TLInt flags, int flag)
{
return(obj != null && IsSet(flags, flag) ? obj.ToBytes() : new byte[] {});
}
