Add CryptoBackend

CHANGES.md

@@ -80,6 +80,9 @@ To be released.
  -  Added `Block<T>.Deserialize(byte[])` method.  [[#751]]
  -  Added `Transaction<T>.Deserialize(byte[])` method.  [[#751]]
  -  Added `StoreExtension.Copy(this IStore, IStore)` extension method.  [[#753]]
+ -  Added `CryptoConfig` class.  [[#758]]
+ -  Added `ICryptoBackend` class.  [[#758]]
+ -  Added `DefaultCryptoBackend` class.  [[#758]]
 
 ### Behavioral changes
 
@@ -177,6 +180,7 @@ To be released.
 [#746]: https://github.com/planetarium/libplanet/pull/746
 [#751]: https://github.com/planetarium/libplanet/pull/751
 [#753]: https://github.com/planetarium/libplanet/pull/753
+[#758]: https://github.com/planetarium/libplanet/pull/758
 
 
 Version 0.7.0

Libplanet/Crypto/CryptoConfig.cs

@@ -0,0 +1,19 @@
+namespace Libplanet.Crypto
+{
+    /// <summary>
+    /// Libplanet cryptography configuration information.
+    /// </summary>
+    public static class CryptoConfig
+    {
+        private static ICryptoBackend _cryptoBackend;
+
+        /// <summary>
+        /// Global cryptography backend to sign and verify messages.
+        /// </summary>
+        public static ICryptoBackend CryptoBackend
+        {
+            get => _cryptoBackend ?? (_cryptoBackend = new DefaultCryptoBackend());
+            set => _cryptoBackend = value;
+        }
+    }
+}

Libplanet/Crypto/DefaultCryptoBackend.cs

@@ -0,0 +1,35 @@
+using System.IO;
+using System.Security.Cryptography;
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Crypto.Signers;
+
+namespace Libplanet.Crypto
+{
+    public class DefaultCryptoBackend : ICryptoBackend
+    {
+        public bool Verify(
+            HashDigest<SHA256> messageHash,
+            byte[] signature,
+            PublicKey publicKey)
+        {
+            try
+            {
+                Asn1Sequence asn1Sequence = (Asn1Sequence)Asn1Object.FromByteArray(signature);
+
+                var rs = new[]
+                {
+                    ((DerInteger)asn1Sequence[0]).Value,
+                    ((DerInteger)asn1Sequence[1]).Value,
+                };
+                var verifier = new ECDsaSigner();
+                verifier.Init(false, publicKey.KeyParam);
+
+                return verifier.VerifySignature(messageHash.ToByteArray(), rs[0], rs[1]);
+            }
+            catch (IOException)
+            {
+                return false;
+            }
+        }
+    }
+}

Libplanet/Crypto/ICryptoBackend.cs

@@ -0,0 +1,26 @@
+using System.Security.Cryptography;
+
+namespace Libplanet.Crypto
+{
+    /// <summary>
+    /// Cryptography backend interface.
+    /// </summary>
+    public interface ICryptoBackend
+    {
+        /// <summary>
+        /// Verifies whether a <paramref name="signature"/> was created from
+        /// a <paramref name="messageHash"/> with the corresponding <see cref="PrivateKey"/>.
+        /// </summary>
+        /// <param name="messageHash">A 32 bytes message hash digest hashed with SHA256.</param>
+        /// <param name="signature">A signature that was created from the
+        /// <paramref name="messageHash"/>.</param>
+        /// <param name="publicKey"><see cref="PublicKey"/> used for verification.</param>
+        /// <returns><c>true</c> if the <paramref name="signature"/> was created
+        /// from the <paramref name="messageHash"/> with the corresponding
+        /// <see cref="PrivateKey"/>. Otherwise <c>false</c>.</returns>
+        bool Verify(
+            HashDigest<SHA256> messageHash,
+            byte[] signature,
+            PublicKey publicKey);
+    }
+}

Libplanet/Crypto/PublicKey.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Diagnostics.Contracts;
-using Org.BouncyCastle.Crypto;
+using System.Security.Cryptography;
+using Org.BouncyCastle.Crypto.Digests;
 using Org.BouncyCastle.Crypto.Parameters;
-using Org.BouncyCastle.Security;
 
 namespace Libplanet.Crypto
 {
@@ -112,23 +112,7 @@ public byte[] Encrypt(byte[] message)
         /// from the <paramref name="message"/> with the corresponding
         /// <see cref="PrivateKey"/>. Otherwise <c>false</c>.</returns>
         [Pure]
-        public bool Verify(byte[] message, byte[] signature) =>
-            Verify(message, signature, "SHA256withECDSA");
-
-        private static ECPublicKeyParameters GetECPublicKeyParameters(byte[] bs)
-        {
-            var ecParams = PrivateKey.GetECParameters();
-            return new ECPublicKeyParameters(
-                "ECDSA",
-                ecParams.Curve.DecodePoint(bs),
-                ecParams
-            );
-        }
-
-        private bool Verify(
-            byte[] message,
-            byte[] signature,
-            string algorithm)
+        public bool Verify(byte[] message, byte[] signature)
         {
             if (message == null)
             {
@@ -140,11 +124,26 @@ private bool Verify(
                 throw new ArgumentNullException(nameof(signature));
             }
 
-            ISigner verifier = SignerUtilities.GetSigner(algorithm);
-            verifier.Init(false, KeyParam);
-            verifier.BlockUpdate(message, 0, message.Length);
+            var h = new Sha256Digest();
+            var hashed = new byte[h.GetDigestSize()];
+            h.BlockUpdate(message, 0, message.Length);
+            h.DoFinal(hashed, 0);
+            h.Reset();
 
-            return verifier.VerifySignature(signature);
+            return CryptoConfig.CryptoBackend.Verify(
+                new HashDigest<SHA256>(hashed),
+                signature,
+                this);
+        }
+
+        private static ECPublicKeyParameters GetECPublicKeyParameters(byte[] bs)
+        {
+            var ecParams = PrivateKey.GetECParameters();
+            return new ECPublicKeyParameters(
+                "ECDSA",
+                ecParams.Curve.DecodePoint(bs),
+                ecParams
+            );
         }
     }
 }