Testing Asymmetric signing.

Author: vplusplus

src/UnitTests/POCs/SignatureSamples.cs

@@ -1,7 +1,10 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Org.Security.Cryptography;
 using System;
 using System.Collections.Generic;
 using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
+
 using System.Text;
 
 namespace UnitTests.POCs
@@ -11,6 +14,16 @@ namespace UnitTests.POCs
     [TestClass]
     public class SignatureSamples
     {
+        // Sender
+        //  Message Or payload - The substance
+        //  Message Digest - A compact representation of the message
+        //  Encrypt the message digest with private key to create signature.
+        // 
+        // Receiver:
+        //  Decrypt the signature using sender's public key
+        //  Hash the message or payload to recreate the message digest
+        //  Compare the hashses
+
         // To verify that data was signed by a particular party, you must have the following information:
         // a) The public key of the party that signed the data.
         // b) The digital signature.
@@ -40,6 +53,67 @@ public void HelloSignature()
 
         }
 
+        [TestMethod]
+        public void TestSignature()
+        {
+            const string CertThumbPrint = "2E3257EE8FC8A72DB3778DFB3F9EDC7D0A9D66C7";
+            const string TEST = "Hello world";
+
+            var payload = Encoding.UTF8.GetBytes(TEST);
+
+            var signature = X509RsaSha1Signature.Sign(payload, CertThumbPrint);
+            var good = X509RsaSha1Signature.Verify(payload, signature, CertThumbPrint);
+            Assert.IsTrue(good);
+
+            signature = X509RsaSha1Signature.Sign(payload, CertThumbPrint);
+            good = X509RsaSha1Signature.Verify(payload, signature, CertThumbPrint);
+            Assert.IsTrue(good);
+
+        }
+
+    }
+
+
+    static class X509RsaSha1Signature
+    {
+        const string SHA1 = "SHA1";
+
+        public static byte[] Sign(byte[] payload, string thumbprint)
+        {
+            X509Certificate2 cert = X509CertificateCache.GetCertificate(thumbprint);
+
+            var rsa = cert.PrivateKey;
+
+            using (var sha = HashAlgorithm.Create(SHA1)) 
+            {
+                byte[] digest = sha.ComputeHash(payload);
+
+                var signatureFormatter = new RSAPKCS1SignatureFormatter(rsa);
+                signatureFormatter.SetHashAlgorithm(SHA1);
+
+                byte[] signature = signatureFormatter.CreateSignature(digest);
+                return signature;
+            }
+        }
+
+        public static bool Verify(byte[] payload, byte[] signature, string thumbprint)
+        {
+            X509Certificate2 cert = X509CertificateCache.GetCertificate(thumbprint);
+
+            var rsa = cert.PublicKey.Key;
+
+            using (var sha = HashAlgorithm.Create(SHA1))
+            {
+                byte[] digest = sha.ComputeHash(payload);
+
+                var signatureDeformatter = new RSAPKCS1SignatureDeformatter(rsa);
+                signatureDeformatter.SetHashAlgorithm(SHA1);
+
+                return signatureDeformatter.VerifySignature(digest, signature);
+            }
+        }
+
+
 
     }
 }