feat: make ChameleonHashHelper to ChameleonHashService

Author: twsc-james

EccSDK/ChameleonHashHelper.cs

@@ -5,9 +5,7 @@ namespace EccSDK.Models.ChameleonHash;
 
 public class ChameleonHashRequest
 {
-    public KeyPairDomain KeyPairDomain { get; set; }
     public string Message { get; set; }
-    public BigInteger SessionKey { get; set; }
-    public BigInteger Order { get; set; }
+    public KeyPairDomain KeyPairDomain { get; set; }
     public BigInteger Signature { get; set; }
 }

EccSDK/Models/ChameleonHash/ChameleonHashRequest.cs

@@ -0,0 +1,11 @@
+using EccSDK.models.Keys;
+using Org.BouncyCastle.Math;
+
+namespace EccSDK.Models.ChameleonHash;
+
+public class ChameleonHashVerifyRequest
+{
+    public KeyPairDomain KeyPairDomain { get; set; }
+    public string Message { get; set; }
+    public string StrSignature { get; set; }
+}

EccSDK/Models/ChameleonHash/ChameleonHashVerifyRequest.cs

@@ -4,5 +4,5 @@ namespace EccSDK.models.ChameleonHash;
 
 public class ChameleonSignature
 {
-    public BigInteger Value { get; set; }
+    public string Value { get; set; }
 }

EccSDK/Models/ChameleonHash/ChameleonSignature.cs

@@ -0,0 +1,76 @@
+using EccSDK.models.ChameleonHash;
+using EccSDK.Models.ChameleonHash;
+using EccSDK.models.Keys;
+using EccSDK.Services.Interfaces;
+using Org.BouncyCastle.Math;
+
+namespace EccSDK.Services;
+
+public class ChameleonHashService : IChameleonHashService
+{
+    private readonly KeyPairDomain _keyPairDomain;
+    private readonly ChameleonHash _chameleonHash;
+
+    // Kn = public key
+    // kn = private key
+    public ChameleonHashService(KeyPairDomain keyPairDomain)
+    {
+        _keyPairDomain = keyPairDomain;
+        _chameleonHash = GetChameleonHash(keyPairDomain);
+    }
+
+
+
+    public ChameleonSignature Sign(string message)
+    {
+        // sign = (sessionKey - dn) mod n
+        // dn = H(m) * kn
+        var msgHash = HashHelper.Sha256(message);
+        var dn = msgHash.Multiply(_keyPairDomain.PrivateKey.D);
+
+        var signature = _keyPairDomain.SessionKey.Add(dn).Mod(_keyPairDomain.PublicKey.Parameters.N);
+
+        return new ChameleonSignature
+        {
+            Value = signature.ToString(16)
+        };
+    }
+
+    public bool Verify(ChameleonHashVerifyRequest verifyRequest)
+    {
+        var chameleonHashRequest = new ChameleonHashRequest()
+        {
+            Message = verifyRequest.Message,
+            KeyPairDomain = verifyRequest.KeyPairDomain,
+            Signature = new BigInteger(verifyRequest.StrSignature, 16) 
+        };
+        
+        var chameleonHashCalculated = GetChameleonHashBy(chameleonHashRequest);
+        
+        return chameleonHashCalculated.Value.Equals(_chameleonHash.Value);
+    }
+
+    public ChameleonHash GetChameleonHashBy(ChameleonHashRequest request)
+    {
+        // chameleonHash = [Kn x H(m)] + [P x signature] 
+        var hashedMessage = HashHelper.Sha256(request.Message);
+        var knHash = request.KeyPairDomain.PublicKey.Q.Multiply(hashedMessage);
+        var pSignature =request.KeyPairDomain.PublicKey.Parameters.G.Multiply(request.Signature);
+
+        return new ChameleonHash()
+        {
+            Value = knHash.Add(pSignature)
+        };
+    }
+    
+    private ChameleonHash GetChameleonHash(KeyPairDomain keyPairDomain)
+    {
+        var signature = Sign("init chameleon hash");
+        return GetChameleonHashBy(new ChameleonHashRequest()
+        {
+            Message = "init chameleon hash",
+            KeyPairDomain = keyPairDomain,
+            Signature = new BigInteger(signature.Value, 16) 
+        });
+    }
+}

EccSDK/Services/ChameleonHashService.cs

@@ -0,0 +1,12 @@
+using EccSDK.models.ChameleonHash;
+using EccSDK.Models.ChameleonHash;
+using Org.BouncyCastle.Math.EC;
+
+namespace EccSDK.Services.Interfaces;
+
+public interface IChameleonHashService
+{
+    ChameleonSignature Sign(string message);
+    bool Verify(ChameleonHashVerifyRequest verifyRequest);
+    ChameleonHash GetChameleonHashBy(ChameleonHashRequest request);
+}

EccSDK/Services/Interfaces/IChameleonHashService.cs

@@ -0,0 +1,28 @@
+using EccSDK;
+using EccSDK.Models.ChameleonHash;
+using EccSDK.Services;
+using NUnit.Framework;
+
+namespace EccSdkUnitTest;
+
+[TestFixture]
+public class ChameleonHashServiceTests
+{
+    [Test]
+    public void should_be_pass()
+    {
+        var keyPairDomain = EccGenerator.GetKeyDomain();
+
+        var chameleonHashService = new ChameleonHashService(keyPairDomain);
+
+        var chameleonSignature = chameleonHashService.Sign("Hello world");
+        
+        chameleonHashService.Verify(new ChameleonHashVerifyRequest()
+        {
+            KeyPairDomain = keyPairDomain,
+            Message = "Hello world",
+            StrSignature = chameleonSignature.Value
+        });
+    }
+    
+}