Feature: Add extension method to convert EdDsaSecurityKey to JsonWebKey

src/ScottBrady.IdentityModel/Crypto/ExtendedJsonWebAlgorithmsKeyTypes.cs

@@ -0,0 +1,8 @@
+namespace ScottBrady.IdentityModel.Crypto
+{
+    public static class ExtendedJsonWebAlgorithmsKeyTypes
+    {
+        // https://datatracker.ietf.org/doc/html/draft-ietf-jose-cfrg-curves-06#section-2
+        public const string ECDH = "OKP";
+    }
+}

src/ScottBrady.IdentityModel/Extensions/ExtendedJsonWebKeyConverter.cs

@@ -0,0 +1,23 @@
+using Microsoft.IdentityModel.Tokens;
+using ScottBrady.IdentityModel.Crypto;
+using ScottBrady.IdentityModel.Tokens;
+
+namespace ScottBrady.IdentityModel.Extensions
+{
+    public static class ExtendedJsonWebKeyConverter
+    {
+        public static JsonWebKey ConvertFromEdDsaSecurityKey(EdDsaSecurityKey securityKey)
+        {
+            var parameters = securityKey.EdDsa.Parameters;
+            return new JsonWebKey
+            {
+                Crv = parameters.Curve,
+                X = parameters.X != null ? Base64UrlEncoder.Encode(parameters.X) : null,
+                D = parameters.D != null ? Base64UrlEncoder.Encode(parameters.D) : null,
+                Kty = ExtendedJsonWebAlgorithmsKeyTypes.ECDH,
+                Alg = ExtendedSecurityAlgorithms.EdDsa,
+                CryptoProviderFactory = securityKey.CryptoProviderFactory,
+            };
+        }
+    }
+}

src/ScottBrady.IdentityModel/Tokens/EdDsa.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Security.Cryptography;
 using Org.BouncyCastle.Crypto;
 using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
@@ -9,7 +10,7 @@
 
 namespace ScottBrady.IdentityModel.Tokens;
 
-public class EdDsa
+public class EdDsa: AsymmetricAlgorithm
 {
     internal EdDsaParameters Parameters { get; private init; }
 
@@ -36,7 +37,6 @@ public static EdDsa Create(string curve)
             var generator = new Ed25519KeyPairGenerator();
             generator.Init(new Ed25519KeyGenerationParameters(new SecureRandom()));
             var keyPair = generator.GenerateKeyPair();
-
             return new EdDsa {Parameters = new EdDsaParameters(keyPair, curve)};
         }
 
@@ -60,7 +60,7 @@ public static EdDsa CreateFromJwk(string jwk)
     {
         throw new NotImplementedException();
     }
-        
+
     public byte[] Sign(byte[] input)
     {
         if (input == null) throw new ArgumentNullException(nameof(input));

src/ScottBrady.IdentityModel/Tokens/EdDsaSecurityKey.cs

@@ -36,7 +36,7 @@ public EdDsaSecurityKey(Ed25519PublicKeyParameters keyParameters) : this()
             EdDsa = EdDsa.Create(new EdDsaParameters(ExtendedSecurityAlgorithms.Curves.Ed25519) {X = keyParameters.GetEncoded()});
         }
 
-        public override int KeySize => throw new NotImplementedException();
+        public override int KeySize => EdDsa.KeySize;
 
         [Obsolete("HasPrivateKey method is deprecated, please use PrivateKeyStatus.")]
         public override bool HasPrivateKey => EdDsa.Parameters.D != null;

test/ScottBrady.IdentityModel.Tests/Tokens/ExtendedJsonWebKeyConverterTests.cs

@@ -0,0 +1,23 @@
+using ScottBrady.IdentityModel.Crypto;
+using ScottBrady.IdentityModel.Extensions;
+using ScottBrady.IdentityModel.Tokens;
+using Xunit;
+
+namespace ScottBrady.IdentityModel.Tests.Tokens
+{
+    public class ExtendedJsonWebKeyConverterTests
+    {
+        [Fact]
+        public void JsonWebKeyConverter_ConvertFromEdDsaSecurityKey()
+        {
+            var originKey = new EdDsaSecurityKey(EdDsa.Create(ExtendedSecurityAlgorithms.Curves.Ed25519));
+            var jwk = ExtendedJsonWebKeyConverter.ConvertFromEdDsaSecurityKey(originKey);
+            Assert.NotNull(jwk);
+            Assert.Equal(ExtendedSecurityAlgorithms.Curves.Ed25519, jwk.Crv);
+            Assert.Equal(ExtendedJsonWebAlgorithmsKeyTypes.ECDH, jwk.Kty);
+            Assert.Equal(ExtendedSecurityAlgorithms.EdDsa, jwk.Alg);
+            Assert.NotNull(jwk.D);
+            Assert.NotNull(jwk.X);
+        }
+    }
+}