static void Main()
{
var document = Encoding.UTF8.GetBytes("Document to Sign");
byte[] hashedDocument;
using (var sha256 = SHA256.Create())
{
hashedDocument = sha256.ComputeHash(document);
}
var digitalSignature = new DigitalSignature();
digitalSignature.AssignNewKey();
var signature = digitalSignature.SignData(hashedDocument);
var verified = digitalSignature.VerifySignature(hashedDocument, signature);
Console.WriteLine();
Console.WriteLine(" Original Text = " +
Encoding.Default.GetString(document));
Console.WriteLine();
Console.WriteLine(" Digital Signature = " +
Convert.ToBase64String(signature));
Console.WriteLine();
Console.WriteLine(verified
? "The digital signature has been correctly verified."
: "The digital signature has NOT been correctly verified.");
Console.ReadLine();
}
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;
}
