initial commit

Signing/Program.cs

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+using System.Security.Cryptography;
+using System.Text;
+
+
+
+
+// ---- Hashing example
+var data = "My Passwort";
+
+HashAlgorithm sha = SHA256.Create();
+byte[] result = sha.ComputeHash(Encoding.ASCII.GetBytes(data));
+
+foreach(var byt in result)
+{
+    Console.Write($"{byt:X}");
+}
+// ----
+
+// ---- Signing
+
+/*
+Verifying a digital signature is the opposite of signing data. 
+Verifying a signature will tell you if the signed data has changed 
+or not. When a digital signature is verified, the signature is decrypted 
+using the public key to produce the original hash value. The data that was 
+signed is hashed. If the two hash values match, then the signature has been 
+verified. To do this, write a program.
+
+
+publicKey kann verschlüssen. Nur der privat key kann aber Entschlüssen.
+
+*/
+
+
+// https://learn.microsoft.com/en-us/dotnet/standard/security/cryptographic-signatures
+using SHA256 alg = SHA256.Create();
+
+byte[] data = Encoding.ASCII.GetBytes("Hello, from the .NET Docs!");
+byte[] hash = alg.ComputeHash(data);
+RSAParameters sharedParameters;
+byte[] signedHash;
+
+// Generate signature
+using (RSA rsa = RSA.Create())
+{
+    sharedParameters = rsa.ExportParameters(false); //Public key
+
+    RSAPKCS1SignatureFormatter rsaFormatter = new(rsa);
+    rsaFormatter.SetHashAlgorithm(nameof(SHA256));
+
+    signedHash = rsaFormatter.CreateSignature(hash);
+}
+
+// Verify signature
+using (RSA rsa = RSA.Create())
+{
+    rsa.ImportParameters(sharedParameters); //Public key
+
+    RSAPKCS1SignatureDeformatter rsaDeformatter = new(rsa);
+    rsaDeformatter.SetHashAlgorithm(nameof(SHA256));
+
+    if (rsaDeformatter.VerifySignature(hash, signedHash))
+    {
+        Console.WriteLine("The signature is valid.");
+    }
+    else
+    {
+        Console.WriteLine("The signature is not valid.");
+    }
+}
+
+
+// ----
+
+
+
+