using Org.BouncyCastle.Crypto;

using Org.BouncyCastle.Security;

using Org.BouncyCastle.Utilities.Encoders;

using System;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        byte[] message = Encoding.UTF8.GetBytes("The quick brown fox jumps over the lazy dog");

        byte[] signature = Hex.Decode("3045022064a0148daab8351f120d6d1f84bf00eac30f05d7635e99e87613d40ae24c72f70221008258284663e3def63e64e56a1623bb8f7331e69691a030de56eed15397d5b4da");

        string spkiPem = @"-----BEGIN PUBLIC KEY-----

                        MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEMpHT+HNKM7zjhx0jZDHyzQlkbLV0

                        xk0H/TFo6gfT23ish58blPNhYrFI51Q/czvkAwCtLZz/6s1n/M8aA9L1Vg==

                        -----END PUBLIC KEY-----";

        spkiPem = spkiPem.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\n", "");

        byte[] spkiDer = Convert.FromBase64String(spkiPem);

        AsymmetricKeyParameter pubParam = PublicKeyFactory.CreateKey(spkiDer); // The more comfortable PemReader does not work in this online IDE for some reason (Run-time exception: Operation could destabilize the runtime), therefore import as DER key... 

​

        bool verified = VerifyData(pubParam, message, signature);

        Console.WriteLine("Verification - NET Framework 4.7.2: " + verified);

    }

    private static bool VerifyData(AsymmetricKeyParameter pubParams, byte[] data, byte[] signature)

    {

        var signer = SignerUtilities.GetSigner("SHA-384withECDSA");

        signer.Init(false, pubParams);

        signer.BlockUpdate(data, 0, data.Length);

        return signer.VerifySignature(signature);

    }

}