帶有 C# 和 Bouncy Castle 的 ECDSA 簽名與 MS ECDsa 簽名不匹配

Question

我正在嘗試與來自 Xamarin.Forms 項目的 Apple Music API 進行通信。 Due to the Microsoft ECDsa implementation not being available on Xamarin.Android and Xamarin.iOS I am trying to work around that limitation using the Portable.BouncyCastle Nuget package. 總體而言，該過程似乎按預期工作，但是當嘗試使用簽名的開發人員令牌調用 Apple Music API 時，我總是收到 HTTP/2 401。

我有一個有效的 MS ECDsa 實現，我在 ASP.NET 核心項目中使用它來與 Apple 推送通知服務通信，所以我編寫了一個快速的小演示工具，可以在這兩種方法中生成密鑰，結果：簽名不匹配並且MS ECDsa 變體實際上有效，我從 Apple 獲得了正確的 API 響應。

我在網上看了很多樣本，我看不出我實際上做錯了什么，所以也許這里有人可以指出我正確的方向。

充氣城堡方法：

    public static AsymmetricCipherKeyPair GetKeys(string data)
    {
        var tag = $"{_className}.GetECDsa";
        try
        {
            byte[] byteArray = Encoding.ASCII.GetBytes(data);
            MemoryStream stream = new MemoryStream(byteArray);

            using (TextReader reader = new StreamReader(stream))
            {
                var ecPrivateKeyParameters =
                    (ECPrivateKeyParameters)new PemReader(reader).ReadObject();
                var q = ecPrivateKeyParameters.Parameters.G.Multiply(ecPrivateKeyParameters.D).Normalize();

                var ecPublicKeyParameters = new ECPublicKeyParameters(q, ecPrivateKeyParameters.Parameters);
                return new AsymmetricCipherKeyPair(ecPublicKeyParameters, ecPrivateKeyParameters);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        return null;
    }
    
    public static string CreateToken(AsymmetricCipherKeyPair keyPair, string p8privateKeyId, string teamId, DateTime date)
    {
        var tag = $"{_className}.CreateJwtToken";
        try
        {
            var header = JsonHelper.Serialize(new { alg = "ES256", kid = p8privateKeyId });
            var payload = JsonHelper.Serialize(new { iss = teamId, iat = ToEpoch(date), exp = ToEpoch(date.AddSeconds(15777000)) });

            var headerBase64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(header));
            var payloadBasae64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(payload));
            var unsignedJwtData = $"{headerBase64}.{payloadBasae64}";
            var signature = GetSignature(unsignedJwtData, keyPair);

            return $"{unsignedJwtData}.{Convert.ToBase64String(signature)}";
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        return null;
    }

    private static int ToEpoch(DateTime time)
    {
        var span = DateTime.UtcNow - new DateTime(1970, 1, 1);
        return Convert.ToInt32(span.TotalSeconds);
    }
    
    private static byte[] GetSignature(string plainText, AsymmetricCipherKeyPair key)
    {
        var encoder = new UTF8Encoding();
        var inputData = encoder.GetBytes(plainText);

        var signer = SignerUtilities.GetSigner("SHA-256withECDSA");
        signer.Init(true, key.Private);
        signer.BlockUpdate(inputData, 0, inputData.Length);

        return signer.GenerateSignature();
    }

MS ECDsa 方法：

    public static string GetPrivateKey(string p8privateKey)
    {
        var tag = $"{_className}.GetPrivateKey";
        try
        {
            var dsa = GetECDsa(p8privateKey);
            var keyBytes = dsa.ExportPkcs8PrivateKey();
            return Convert.ToBase64String(keyBytes);
        }
        catch (Exception ex)
        {
           Console.WriteLine(ex.Message);
        }
        return null;
    }
    
    private static ECDsa GetECDsa(string p8privateKey)
    {
        var tag = $"{_className}.GetECDsa";
        try
        {
            byte[] byteArray = Encoding.ASCII.GetBytes(p8privateKey);
            MemoryStream stream = new MemoryStream(byteArray);

            using (TextReader reader = new StreamReader(stream))
            {
                var ecPrivateKeyParameters =
                    (ECPrivateKeyParameters)new PemReader(reader).ReadObject();
                var q = ecPrivateKeyParameters.Parameters.G.Multiply(ecPrivateKeyParameters.D).Normalize();

                return ECDsa.Create(new ECParameters
                {
                    Curve = ECCurve.CreateFromValue(ecPrivateKeyParameters.PublicKeyParamSet.Id),
                    D = ecPrivateKeyParameters.D.ToByteArrayUnsigned(),
                    Q =
                        {
                            X = q.XCoord.GetEncoded(),
                            Y = q.YCoord.GetEncoded()
                        }
                });
            }
        }
        catch (Exception ex)
        {
           Console.WriteLine(ex.Message);
        }
        return null;
    }
    
    public static string CreateJwtToken(string p8privateKey, string p8privateKeyId, string teamId, DateTime date)
    {
        var tag = $"{_className}.CreateJwtToken";
        try
        {
            var header = JsonHelper.Serialize(new { alg = "ES256", kid = p8privateKeyId });
            var payload = JsonHelper.Serialize(new { iss = teamId, iat = ToEpoch(date), exp = ToEpoch(date.AddSeconds(15777000)) });

            using var dsa = ECDsa.Create("ECDsa");

            var keyBytes = Convert.FromBase64String(p8privateKey);
            dsa.ImportPkcs8PrivateKey(keyBytes, out _);

            var headerBase64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(header));
            var payloadBasae64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(payload));
            var unsignedJwtData = $"{headerBase64}.{payloadBasae64}";
            var unsignedJwtBytes = Encoding.UTF8.GetBytes(unsignedJwtData);
            var signature = dsa.SignData(unsignedJwtBytes, 0, unsignedJwtBytes.Length, HashAlgorithmName.SHA256);

            return $"{unsignedJwtData}.{Convert.ToBase64String(signature)}";
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        return null;
    }

我期待着您的反饋。

Answer 1

感謝Topaco的評論，我用SHA-256withPLAIN-ECDSA進行了測試，它解決了這個問題。 簽名不相同，但 Apple Music API 接受簽名的 JWT 令牌並正確響應。 因此，感謝 Topaco 指出這一點。