public static void ReceiveMessage(AsymmetricKeyParameter rsaKey)
{
string transfer = File.ReadAllText("../../TransferData.json");
TransferData transferData = JsonConvert.DeserializeObject <TransferData>(transfer);
byte[] encryptedSecret = transferData.RsaEncryptedSecret.HexToByteArray();
byte[] decryptedSecret = EncryptionUtils.RsaProcessMessage(
false, encryptedSecret, rsaKey);
Console.WriteLine("Transfer data received. Decrypted secret (RSA):\r\n" + Utils.ToString(decryptedSecret));
byte[] encryptedMessage = transferData.AesEncryptedMessage.HexToByteArray();
byte[] iv = transferData.AesIV.HexToByteArray();
byte[] decryptedMessage = EncryptionUtils.AesCtrDecrypt(
encryptedMessage, iv, decryptedSecret);
Console.WriteLine("Decrytped message (AES):\r\n" + Utils.ToUTF8String(decryptedMessage));
byte[] hmacKey = transferData.HmacKey.HexToByteArray();
byte[] messageHmac = HashUtils.ComputeHmac("HMACSHA256", decryptedMessage, hmacKey);
string decryptedMessageHmac = Utils.ToString(messageHmac);
bool validMessage = decryptedMessageHmac == transferData.MessageHmac;
Console.WriteLine(
"Decrytped message integrity check:\r\n" +
(validMessage ? "Passed" : "Failed"));
}
public static void SendMessage(string message, AsymmetricKeyParameter rsaKey)
{
Console.WriteLine("Message before sending:\r\n" + message);
byte[] messageBytes = Utils.GetBytes(message);
// used as the key for AES encryption
byte[] secret = EncryptionUtils.GetRandomBytes(32);
Console.WriteLine("AES secret before sending:\r\n" + Utils.ToString(secret));
// encrypt the shared secret using RSA
byte[] encryptedSecret = EncryptionUtils.RsaProcessMessage(
true, secret, rsaKey);
// encrypt the message with the shared secret as key using AES
byte[] iv = EncryptionUtils.GetRandomBytes(16);
byte[] encryptedMessage = EncryptionUtils.AesCtrEncrypt(messageBytes, iv, secret);
byte[] hmacKey = EncryptionUtils.GetRandomBytes(32);
byte[] messageHmac = HashUtils.ComputeHmac(messageBytes, hmacKey, 256);
TransferData transferData = new TransferData
{
AesEncryptedMessage = Utils.ToString(encryptedMessage),
AesIV = Utils.ToString(iv),
HmacKey = Utils.ToString(hmacKey),
MessageHmac = Utils.ToString(messageHmac),
RsaEncryptedSecret = Utils.ToString(encryptedSecret)
};
string output = JsonUtils.Serialize(transferData);
File.WriteAllText("../../../TransferData.json", output);
}
private static void Main(string[] args)
{
Console.WriteLine(
"HMAC-SHA-512{0}{1}",
Environment.NewLine,
Utils.ToString(HashUtils.ComputeHmac(
Utils.GetBytes("blockchain"),
Utils.GetBytes("devcamp"),
512)));
}
private static void Main(string[] args)
{
byte[] passphrase = Utils.GetBytes("p@$$w0rd~3");
byte[] message = Utils.GetBytes("exercise-cryptography");
//byte[] scryptSalt = EncryptionUtils.GetRandomBytes(256 / 8);
byte[] scryptSalt = "7b07a2977a473e84fc30d463a2333bcfea6cb3400b16bec4e17fe981c925ba4f".HexToByteArray();
int scryptCost = 16384;
int scryptBlockSize = 16;
int scryptParallelization = 1;
int scryptDesiredKeyBitLength = 512;
byte[] scryptKey = EncryptionUtils.GenerateSCryptKey(
passphrase,
scryptSalt,
scryptCost,
scryptBlockSize,
scryptParallelization,
scryptDesiredKeyBitLength);
Console.WriteLine("Scrypt key: " + Utils.ToString(scryptKey));
byte[] encryptionKey = new byte[scryptKey.Length / 2];
Array.Copy(scryptKey, encryptionKey, encryptionKey.Length);
Console.WriteLine("Encryption key: " + Utils.ToString(encryptionKey));
byte[] hmacKey = new byte[scryptKey.Length / 2];
Array.Copy(scryptKey, hmacKey.Length, hmacKey, 0, hmacKey.Length);
Console.WriteLine("HMAC-SHA256 key: " + Utils.ToString(hmacKey));
BufferedBlockCipher twofishCipher = EncryptionUtils.GetTwofishCipher();
int cipherBlockSize = twofishCipher.GetBlockSize();
//byte[] iv = EncryptionUtils.GetRandomBytes(cipherBlockSize);
byte[] iv = "433e0d8557a800a40c1d3b54f6636ff5".HexToByteArray();
byte[] twofishEncryptedMessage = EncryptionUtils.BlockCipherProcessMessage(
twofishCipher,
true,
message,
encryptionKey,
iv);
string hmacHashedMessage =
HashUtils.ComputeHmac(message, hmacKey, 256).ToHex();
string outputJson = GetEncryptionResultJson(
scryptSalt,
scryptCost,
scryptBlockSize,
scryptParallelization,
scryptDesiredKeyBitLength,
iv,
twofishEncryptedMessage,
hmacHashedMessage);
File.WriteAllText("../../../Output.json", outputJson);
Console.WriteLine(outputJson);
byte[] twofishDecryptedMessage = EncryptionUtils.BlockCipherProcessMessage(
twofishCipher,
false,
twofishEncryptedMessage,
encryptionKey,
iv);
Console.WriteLine("Decrypted message: {0}", Utils.ToUTF8String(twofishDecryptedMessage));
}
