private byte[] computeAuthKey(TLPhoneCallAccepted call)
{
BigInteger p = new BigInteger(1, secretP);
BigInteger i_authKey = new BigInteger(1, call.GB);
i_authKey = i_authKey.ModPow(new BigInteger(1, a_or_b), p);
byte[] authKey = i_authKey.ToByteArray();
if (authKey.Length > 256)
{
byte[] correctedAuth = new byte[256];
Buffer.BlockCopy(authKey, authKey.Length - 256, correctedAuth, 0, 256);
authKey = correctedAuth;
}
else if (authKey.Length < 256)
{
byte[] correctedAuth = new byte[256];
Buffer.BlockCopy(authKey, 0, correctedAuth, 256 - authKey.Length, authKey.Length);
for (int a = 0; a < 256 - authKey.Length; a++)
{
authKey[a] = 0;
}
authKey = correctedAuth;
}
return(authKey);
}
private void ProcessAcceptedCall(TLPhoneCallAccepted phoneCallAccepted)
{
DispatchStateChanged(PhoneCallState.STATE_EXCHANGING_KEYS);
if (!TLUtils.CheckGaAndGb(phoneCallAccepted.GB.Data, _secretP.Data))
{
CallFailed();
return;
}
_authKey = MTProtoService.GetAuthKey(_aOrB, phoneCallAccepted.GB.ToBytes(), _secretP.ToBytes());
var keyHash = Utils.ComputeSHA1(_authKey);
var keyFingerprint = new TLLong(BitConverter.ToInt64(keyHash, 12));
var peer = new TLInputPhoneCall
{
Id = phoneCallAccepted.Id,
AccessHash = phoneCallAccepted.AccessHash
};
var protocol = new TLPhoneCallProtocol
{
Flags = new TLInt(0),
UdpP2P = true,
UdpReflector = true,
MinLayer = new TLInt(CALL_MIN_LAYER),
MaxLayer = new TLInt(CALL_MAX_LAYER)
};
_mtProtoService.ConfirmCallAsync(peer, TLString.FromBigEndianData(_ga), keyFingerprint, protocol,
result =>
{
_call = result;
InitiateActualEncryptedCall();
},
error =>
{
CallFailed();
});
}
