Implement ECDsa and ECDsaCng

Author: Atsushi Kanamori

src/Common/tests/Cryptography/AlgorithmImplementations/ECDsa/ECDsaFactory.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace System.Security.Cryptography.EcDsa.Tests
+{
+    public interface IECDsaProvider
+    {
+        ECDsa Create();
+        ECDsa Create(int keySize);
+    }
+
+    public static partial class ECDsaFactory
+    {
+        public static ECDsa Create()
+        {
+            return s_provider.Create();
+        }
+
+        public static ECDsa Create(int keySize)
+        {
+            return s_provider.Create(keySize);
+        }
+    }
+}

src/Common/tests/Cryptography/AlgorithmImplementations/ECDsa/ECDsaStub.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.IO;
+using System.Security.Cryptography;
+
+namespace System.Security.Cryptography.EcDsa.Tests
+{
+    // Stub out the last remaining abstract members to throw NotImplementedException
+    internal class ECDsaStub : ECDsa
+    {
+        public override byte[] SignHash(byte[] hash)
+        {
+            return Array.Empty<byte>();
+        }
+
+        public override bool VerifyHash(byte[] hash, byte[] signature)
+        {
+            return false;
+        }
+
+        protected override byte[] HashData(byte[] data, int offset, int count, HashAlgorithmName hashAlgorithm)
+        {
+            throw new NotImplementedException();
+        }
+
+        protected override byte[] HashData(Stream data, HashAlgorithmName hashAlgorithm)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}