private static void Main()
{
// TODO : Take a document (that is a string and convert it to a byte array
// TODO : Hash that document with sha256
// TODO : Create a new RSA key pair
// TODO : Create a digital signature of the hash
// TODO : Check that you can verify the signature correctly.
// TODO : Tamper with the document and then try to re-verify the signature.
var input = "Hello, World!";
var hash = ComputeHashSha256(Encoding.UTF8.GetBytes(input));
var rsa = new DigitalSignature();
rsa.AssignNewKey();
var digitalSignatur = rsa.SignData(hash);
var isValid = rsa.VerifySignature(hash, digitalSignatur);
Console.WriteLine("Untampered");
Console.WriteLine($"The Signature is valid {isValid}");
Console.WriteLine();
Console.WriteLine("Tampered");
input = $"{input}."; //Added . to input
var tamperedHash = ComputeHashSha256(Encoding.UTF8.GetBytes(input));
isValid = rsa.VerifySignature(tamperedHash, digitalSignatur);
Console.WriteLine($"The Signature is valid {isValid}");
}
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("Digital Signature Demonstration in .NET");
Console.WriteLine("---------------------------------------");
Console.WriteLine();
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();
}
