public EncryptedPacket EncryptData(byte[] original, RSAWithRSAParameterKey rsaParams, DigitalSignatureFuncs digitalSignature)
{
// Generate our session key
var sessionKey = _aes.GenerateRandomNumber(32);
// Create the encrypted packet and generate the IV
var encryptedPacket = new EncryptedPacket
{
IV = _aes.GenerateRandomNumber(16)
};
// Encrypt our data with AES
encryptedPacket.EncryptedData = _aes.Encrypt(original, sessionKey, encryptedPacket.IV);
// Encrypt the session key with RSA
encryptedPacket.EncryptedSessionKey = rsaParams.EncryptData(sessionKey);
// Calculate a HMAC
encryptedPacket.HMAC = HMac.ComputeHMACSha256(encryptedPacket.EncryptedData, sessionKey);
// Generate digital signature of packet to send
encryptedPacket.Signature = digitalSignature.SignData(encryptedPacket.HMAC);
return(encryptedPacket);
}
private static void TestDigitalSignature()
{
var document = Encoding.UTF8.GetBytes("Document to Sign");
byte[] hashedDocument;
using (var sha256 = SHA256.Create())
{
hashedDocument = sha256.ComputeHash(document);
}
var digitalSignature = new DigitalSignatureFuncs();
digitalSignature.AssignNewKey();
var signature = digitalSignature.SignData(hashedDocument);
var verified = digitalSignature.VerifySignature(hashedDocument, signature);
Console.WriteLine($"Original Text: {Encoding.Default.GetString(document)}");
Console.WriteLine($"Digital Signature: {Convert.ToBase64String(signature)}");
Console.WriteLine(verified ? "The digital signature has been verified." : "The digital signature has NOT been verified.");
}
