/// <summary>
/// Alice and Bob communicate successfully with correct signature
/// </summary>
private static void SimulateSendMessageWithValidSignature()
{
WriteLine("Alice joined!");
WriteLine("Bob joined!");
Write("Alice enter some text to sign:");
string data = ReadLine();
var signature = SignatureProtector.GenerateSignature(data);
WriteLine($"Alice send to Bob a public key {SignatureProtector.PublicKey}");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Alice send to Bob signature {signature}");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Alice send to Bob a text message {data}");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Bob use Alice's generated signature to validate the message");
if (SignatureProtector.ValidateSignature(data, signature))
{
WriteLine("Correct! Signature is valid.");
WriteLine("This message is sent by Alice.");
}
else
{
WriteLine("Invalid signature.");
}
}
/// <summary>
/// Alice and Bob communicate fail because Middle-Man modified the signature
/// </summary>
private static void SimulateSignatureModifiedByMiddleMan()
{
WriteLine("Alice joined!");
WriteLine("Bob joined!");
Write("Alice enter some text to sign:");
string data = ReadLine();
var signature = SignatureProtector.GenerateSignature(data);
WriteLine($"Alice send to Bob a public key {SignatureProtector.PublicKey}");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Alice send to Bob signature {signature}");
WriteLine(". . . . .");
WriteLine("Middle Man joined!");
WriteLine("Middle Man modify the signature!");
var fakeSignature = signature.Replace(signature[0], 'X');
WriteLine($"Middle Man re-send to Bob fake signature");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Alice send to Bob a text message {data}");
WriteLine(". . . . .");
WriteLine("Bob received");
WriteLine($"Bob use Alice's generated signature to validate the message");
if (SignatureProtector.ValidateSignature(data, fakeSignature))
{
WriteLine("Correct! Signature is valid.");
WriteLine("This message is sent by Alice.");
}
else
{
WriteLine($"Invalid signature {fakeSignature}.");
WriteLine("This message is sent by Alice but was modifed by somebody from the Internet.");
}
}