From 82779add803eeeb7cb15b1118b08352b015454fc Mon Sep 17 00:00:00 2001
From: Shargon <shargon@gmail.com>
Date: Fri, 16 Jul 2021 01:01:03 -0500
Subject: [PATCH] OSX compatible (#2511)

---
 src/neo/Cryptography/Crypto.cs | 54 ++++++++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 13 deletions(-)

diff --git a/src/neo/Cryptography/Crypto.cs b/src/neo/Cryptography/Crypto.cs
index aec25ecd09..3b042fd8b5 100644
--- a/src/neo/Cryptography/Crypto.cs
+++ b/src/neo/Cryptography/Crypto.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.InteropServices;
 using System.Security.Cryptography;
 
 namespace Neo.Cryptography
@@ -8,6 +9,8 @@ namespace Neo.Cryptography
     /// </summary>
     public static class Crypto
     {
+        private static readonly bool IsOSX = RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+
         /// <summary>
         /// Calculates the 160-bit hash value of the specified message.
         /// </summary>
@@ -59,21 +62,46 @@ public static byte[] Sign(byte[] message, byte[] prikey, byte[] pubkey)
         /// <returns><see langword="true"/> if the signature is valid; otherwise, <see langword="false"/>.</returns>
         public static bool VerifySignature(ReadOnlySpan<byte> message, ReadOnlySpan<byte> signature, ECC.ECPoint pubkey)
         {
-            ECCurve curve =
-                pubkey.Curve == ECC.ECCurve.Secp256r1 ? ECCurve.NamedCurves.nistP256 :
-                pubkey.Curve == ECC.ECCurve.Secp256k1 ? ECCurve.CreateFromFriendlyName("secP256k1") :
-                throw new NotSupportedException();
-            byte[] buffer = pubkey.EncodePoint(false);
-            using var ecdsa = ECDsa.Create(new ECParameters
+            if (signature.Length != 64) return false;
+
+            if (IsOSX && pubkey.Curve == ECC.ECCurve.Secp256k1)
             {
-                Curve = curve,
-                Q = new ECPoint
+                var curve = Org.BouncyCastle.Asn1.Sec.SecNamedCurves.GetByName("secp256k1");
+                var domain = new Org.BouncyCastle.Crypto.Parameters.ECDomainParameters(curve.Curve, curve.G, curve.N, curve.H);
+                var point = curve.Curve.CreatePoint(
+                    new Org.BouncyCastle.Math.BigInteger(pubkey.X.Value.ToString()),
+                    new Org.BouncyCastle.Math.BigInteger(pubkey.Y.Value.ToString()));
+                var pubKey = new Org.BouncyCastle.Crypto.Parameters.ECPublicKeyParameters("ECDSA", point, domain);
+                var signer = Org.BouncyCastle.Security.SignerUtilities.GetSigner("SHA-256withECDSA");
+
+                signer.Init(false, pubKey);
+                signer.BlockUpdate(message.ToArray(), 0, message.Length);
+
+                var sig = signature.ToArray();
+                var r = new Org.BouncyCastle.Math.BigInteger(1, sig, 0, 32);
+                var s = new Org.BouncyCastle.Math.BigInteger(1, sig, 32, 32);
+                sig = new Org.BouncyCastle.Asn1.DerSequence(new Org.BouncyCastle.Asn1.DerInteger(r), new Org.BouncyCastle.Asn1.DerInteger(s)).GetDerEncoded();
+
+                return signer.VerifySignature(sig);
+            }
+            else
+            {
+                ECCurve curve =
+                    pubkey.Curve == ECC.ECCurve.Secp256r1 ? ECCurve.NamedCurves.nistP256 :
+                    pubkey.Curve == ECC.ECCurve.Secp256k1 ? ECCurve.CreateFromFriendlyName("secP256k1") :
+                    throw new NotSupportedException();
+                byte[] buffer = pubkey.EncodePoint(false);
+                using var ecdsa = ECDsa.Create(new ECParameters
                 {
-                    X = buffer[1..33],
-                    Y = buffer[33..]
-                }
-            });
-            return ecdsa.VerifyData(message, signature, HashAlgorithmName.SHA256);
+                    Curve = curve,
+                    Q = new ECPoint
+                    {
+                        X = buffer[1..33],
+                        Y = buffer[33..]
+                    }
+                });
+                return ecdsa.VerifyData(message, signature, HashAlgorithmName.SHA256);
+            }
         }
 
         /// <summary>