Sanity check in PrivateKey constructor using bytes

CHANGES.md

@@ -82,6 +82,7 @@ To be released.
     the `Transaction<T>` more than once.  [[#413]]
  -  `BlockChain<T>.Swap()` became to omit common block finding when `render` is
     `false`.  [[#423]]
+ -  `PrivateKey(bytes)` became to valid check.  [[#438]]
 
 ### Bug fixes
 
@@ -144,6 +145,7 @@ To be released.
 [#424]: https://github.com/planetarium/libplanet/pull/424
 [#426]: https://github.com/planetarium/libplanet/pull/426
 [#434]: https://github.com/planetarium/libplanet/pull/434
+[#438]: https://github.com/planetarium/libplanet/pull/438
 [LiteDB #1268]: https://github.com/mbdavid/LiteDB/issues/1268
 [floating-point determinism]: https://wp.me/p1fTCO-kT
 

Libplanet.Tests/Crypto/PrivateKeyTest.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Text;
 using Libplanet.Crypto;
 using Xunit;
@@ -20,6 +21,17 @@ public void BytesTest()
             Assert.Equal(bs, key.ByteArray);
         }
 
+        [Fact]
+        public void BytesSanityCheckTest()
+        {
+            var bs = new byte[]
+            {
+                0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+                0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+            };
+            Assert.Throws<InvalidOperationException>(() => new PrivateKey(bs));
+        }
+
         [Fact]
         public void PublicKeyTest()
         {

Libplanet/Crypto/PrivateKey.cs

@@ -69,11 +69,7 @@ public PrivateKey()
         /// <seealso cref="ByteArray"/>
         public PrivateKey(byte[] privateKey)
             : this(
-                new ECPrivateKeyParameters(
-                    "ECDSA",
-                    new BigInteger(1, privateKey),
-                    GetECParameters()
-                )
+                GenerateKeyFromBytes(privateKey)
             )
         {
         }
@@ -269,6 +265,29 @@ private static ECPrivateKeyParameters GenerateKeyParam()
             return gen.GenerateKeyPair().Private as ECPrivateKeyParameters;
         }
 
+        private static ECPrivateKeyParameters GenerateKeyFromBytes(byte[] privateKey)
+        {
+            var param = new ECPrivateKeyParameters(
+                "ECDSA",
+                new BigInteger(1, privateKey),
+                GetECParameters()
+            );
+
+            var key = new PrivateKey(param);
+            try
+            {
+                var publicKey = key.PublicKey;
+            }
+            catch (ArgumentException)
+            {
+                throw new InvalidOperationException(
+                    "Infinity is not a valid public key for ECDH"
+                );
+            }
+
+            return param;
+        }
+
         private ECPoint CalculatePoint(ECPublicKeyParameters pubKeyParams)
         {
             ECDomainParameters dp = keyParam.Parameters;