using System.Globalization;

using System.Security.Cryptography;

using System.Security.Cryptography.X509Certificates;

​

Test();

System.Console.ReadLine();

​

static void Test()

{

    // Data signed from the mobile app (first app example provided)

    var mobileAppDataHex = "03a239ddb1ede15dfb43881671930cf6fcbda4b698b1b6f64c0a91aa58aea7171a";

    var mobileAppSignedDataHex = "f90191b01af0826d1bf553712baf72b23e8a723b888ff6390d06e8c4ccd5b684dde17e588990198ae9afcddf806400ff2c0716f1559971c65f1be4fccf0bf5a5";

    var mobileAppResult = VerifySignature(mobileAppDataHex, mobileAppSignedDataHex);

    System.Console.WriteLine($"Mobile result: {mobileAppResult}"); // Mobile result: True

​

    // Data signed by NM using openSSL

    var openSslDataHex = "03cff911f07e4d308f986af959d676b65c2e8127136adba4e84ea2293e78fc6903";

    var openSslSignedDataHex = "3046022100cc724299345c294d0bbd8540d6a409525784c38dfaa1417449970648f414dc23022100c2b06e7e763bab93961796717d9459dee87aea3c44846e6a84b1267c226447ca";

    var openSslDataResult = VerifySignature(openSslDataHex, openSslSignedDataHex);

    System.Console.WriteLine($"Open SSL result: {openSslDataResult}");    // Open SSL result: False

}

​

static bool VerifySignature(string dataHex, string signatureHex)

{

    // App certificate (public)

    var cert = X509Certificate2.CreateFromPem(@"-----BEGIN CERTIFICATE-----

MIIFATCCAumgAwIBAgICEAAwDQYJKoZIhvcNAQELBQAwfzELMAkGA1UEBhMCRlIx

ETAPBgNVBAgMCEJhcy1SaGluMQ8wDQYDVQQKDAZTZXdvc3kxCzAJBgNVBAsMAklU

MRwwGgYDVQQDDBNhcHAuaW50ZXJtZWRpYXRlLmNhMSEwHwYJKoZIhvcNAQkBFhJu

b3JlcGx5QHNld29zeS5uZXQwHhcNMjIwOTI2MTM1MDQ5WhcNMzIwOTIzMTM1MDQ5

WjCBkTELMAkGA1UEBhMCRlIxETAPBgNVBAgMCEJhcy1SaGluMREwDwYDVQQHDAhI

YWd1ZW5hdTEPMA0GA1UECgwGU2V3b3N5MQswCQYDVQQLDAJJVDEbMBkGA1UEAwwS

YXBwLmtlb2xhLnVzZXIuMC4xMSEwHwYJKoZIhvcNAQkBFhJub3JlcGx5QHNld29z

eS5uZXQwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAQ1w49fH40Y7lcWDBkDiKM4

FehPK2aosK4sIH1PYWx/yfRou0LCMIz9uR29ZprOfQnZI3QJfGTJW9kCVOhjsiDj

o4IBPTCCATkwCQYDVR0TBAIwADARBglghkgBhvhCAQEEBAMCBBAwMwYJYIZIAYb4

QgENBCYWJE9wZW5TU0wgR2VuZXJhdGVkIFNlcnZlciBDZXJ0aWZpY2F0ZTAdBgNV

HQ4EFgQU/WiIIbSJmaZ68MM6Spa5UjhZqagwgbQGA1UdIwSBrDCBqYAU7mEgR89B

dRAqNGJ6Xkee/7Tk14yhgYykgYkwgYYxCzAJBgNVBAYTAkZSMREwDwYDVQQIDAhC

YXMtUmhpbjERMA8GA1UEBwwISGFndWVuYXUxDzANBgNVBAoMBlNld29zeTELMAkG

A1UECwwCSVQxEDAOBgNVBAMMB1Jvb3QgQ0ExITAfBgkqhkiG9w0BCQEWEm5vcmVw

bHlAc2V3b3N5Lm5ldIICEAEwDgYDVR0PAQH/BAQDAgWgMA0GCSqGSIb3DQEBCwUA

A4ICAQCyxAxICiZ+yFzXs2Rslkrd6/IHhmXVvm/bTegyjaG3lW6F+wBh65GEoNU0

XxYlUk4AhwwSE3MHwQ15EOnAHUtT3LRWU8shjpHDTMSzyx/NNa6fLPbYq6MmEOV0

wMdZ2rBkXfzRVK+3DKuGQ3LuXuJaBBNbD1l4LubDm/GEX8QVpu2mxzrHib6dpwHi

g5AKLTsEN1wojpJ2ryjUfXEhfbyqt3xlU0eryXBpZZkPYsjr56wXzAhymR0pgOJ3

YxdvSl9RwtiTmtqlKh2dqJU4wzpKE53MKU2kv/W527T/mlJQy3IsVfVWDy5tkX89

UfK3oW8bXDaGVTywzb9gD3Bu5mL9zweOxiFlPSeUlqEvYS1qyzwnqHXBevlbZYVU

zA466dAcJxZ8Da/V6pPU+16jbPqftJgj+mDrDClrKudxzIo8PVmDqUGE3g48elji

4+27PIf2VNwuEdll4EJ4B0b7DfHU7O9Cgxg21zxUMRnsqUjz9ERbHV3ojZ/N/wy6

QXNVivPMFUz5lN4SaVZnSVlC4Sm2UX4DIr6Ak16RrNpf366K24Akav9zJaVknfkk

nDoB+J3nrqY+8qqUrjR5OU7zUNRlToKZi1jjuzsVJxJ0qE1BxR0c0iwNfxuQKFhT

HcPmRf5tG4RTU+BfyCbwzVbmIAht8CoopucsQh1dM31RSOQSIQ==

-----END CERTIFICATE-----");

​

    // Gets public key from certificate

    var publicKey = cert.PublicKey.GetECDsaPublicKey()!;

​

    // Converts hex input to byte arrays

    var signatureBytes = ConvertHexStringToByteArray(signatureHex);

    var data = ConvertHexStringToByteArray(dataHex);

​

    // Verify the signature using the public key

    return publicKey.VerifyData(data, signatureBytes, HashAlgorithmName.SHA256);

}

​

static byte[] ConvertHexStringToByteArray(string hexString)

{

    var data = new byte[hexString.Length / 2];

    for (int index = 0; index < data.Length; index++)

    {

        string byteValue = hexString.Substring(index * 2, 2);

        data[index] = byte.Parse(byteValue, NumberStyles.HexNumber, CultureInfo.InvariantCulture);

    }

​

    return data;

}