public static Akep2Message3 FromString(string str, byte[] longTermKey)
{
var contentBytes = PemParser.GetMessageContentBytes(str);
var contentObjectsList = (List <object>)SksAsn1Parser.Parse(contentBytes);
var iv = (byte[])contentObjectsList[0];
var encryptedPart = (byte[])contentObjectsList[1];
var hmacPart = (byte[])contentObjectsList[2];
var myHmac = SksHmac.Hash(longTermKey, encryptedPart);
if (!Utils.CompareByteArrays(hmacPart, myHmac))
{
Logger.Log("AKEP2MESSAGE2:", "Hmac doesn't match");
return(null);
}
var decryptedSequence = SksAes.DecryptBytesFromBytes_Aes(encryptedPart, longTermKey, iv);
contentObjectsList = (List <object>)SksAsn1Parser.Parse(decryptedSequence);
var a = (string)contentObjectsList[0];
var nonceB = (byte[])contentObjectsList[1];
return(new Akep2Message3(a, nonceB, longTermKey));
}
public void SendChatMessage(string message)
{
Logger.Log(GetWholeLogTag(), $"SendChatMessage - Message: {message}");
var secret = GetSecretFromProtocol();
if (secret == null)
{
Logger.Log("USER:"******"Secret is null");
return;
}
var iv = Utils.GenerateRandom16();
var encryptedMessageBytes = SksAes.EncryptStringToBytes_Aes(message, secret, iv);
var hmacBytes = SksHmac.Hash(secret, Utils.StringToBytes(message));
Logger.Log(GetWholeLogTag(), $"SendChatMessage - EcnryptedBytes: {string.Join(",", encryptedMessageBytes)}");
Logger.Log(GetWholeLogTag(), $"SendChatMessage - Hmac: {string.Join(",", hmacBytes)}");
var chatMessage = new ChatMessage(iv, encryptedMessageBytes, hmacBytes);
var finalMessage = chatMessage.ToString();
Client.SendMessage(finalMessage);
}
public byte[] GetSecret()
{
var key = keyBytes.ToList();
key[key.Count - 1]++;
// todo: nonceB je null
return(SksHmac.Hash(key.ToArray(), NonceB));
}
public Akep2Message3(string a, byte[] nonceB, byte[] longTermKey)
{
Iv = Utils.GenerateRandom16();
A = a;
NonceB = nonceB;
var objects = new List <object> {
A, NonceB
};
var sequence = SksAsn1Encoder.EncodeSequence(objects);
EncryptedPart = SksAes.EncryptBytes_Aes(sequence, longTermKey, Iv);
HmacPart = SksHmac.Hash(longTermKey, sequence);
}