public byte[] DecryptData(EncryptedPacket encryptedPacket, RSAWithRSAParameterKey rsaParams,
DigitalSignature digitalSignature)
{
var decryptedSessionKey = rsaParams.DecryptData(encryptedPacket.EncryptedSessionKey);
using (var hmac = new HMACSHA256(decryptedSessionKey))
{
var hmacToCheck = hmac.ComputeHash(encryptedPacket.EncryptedData);
if (!Compare(encryptedPacket.Hmac, hmacToCheck)){
throw new CryptographicException(
"HMAC for decryption does not match encrypted packet.");
}
if (!digitalSignature.VerifySignature(encryptedPacket.Hmac,
encryptedPacket.Signature)){
throw new CryptographicException(
"Digital Signature can not be verified.");
}
}
var decryptedData = _aes.Decrypt(encryptedPacket.EncryptedData, decryptedSessionKey,
encryptedPacket.Iv);
return decryptedData;
}
public byte[] DecryptData(EncryptedPacket encryptedPacket, RSAWithRSAParameterKey rsaParams)
{
// Decrypt AES Key with RSA and then decrypt data with AES.
var decryptedSessionKey = rsaParams.DecryptData(encryptedPacket.EncryptedSessionKey);
using (var hmac = new HMACSHA256(decryptedSessionKey))
{
var hmacToCheck = hmac.ComputeHash(encryptedPacket.EncryptedData);
if (!Compare(encryptedPacket.Hmac, hmacToCheck))
{
throw new CryptographicException("HMAC for decryption does not match encrypted packet.");
}
}
var decryptedData = _aes.Decrypt(encryptedPacket.EncryptedData, decryptedSessionKey, encryptedPacket.Iv);
return(decryptedData);
}
private static void RsaWithRsaParameterKey()
{
var rsaParams = new RSAWithRSAParameterKey();
const string original = "Text to encrypt";
rsaParams.AssignNewKey();
var encryptedRsaParams = rsaParams.EncryptData(Encoding.UTF8.GetBytes(original));
var decryptedRsaParams = rsaParams.DecryptData(encryptedRsaParams);
Console.WriteLine();
Console.WriteLine("In Memory Key");
Console.WriteLine();
Console.WriteLine(" Original Text = " + original);
Console.WriteLine();
Console.WriteLine(" Encrypted Text = " + Convert.ToBase64String(encryptedRsaParams));
Console.WriteLine();
Console.WriteLine(" Decrypted Text = " + Encoding.Default.GetString(decryptedRsaParams));
Console.WriteLine();
Console.WriteLine();
}
