.net client

[Varorbc]

@bestbeforetoday I have used the C# language to implement the client, but when I evaluated the proposal, the gateway gave me the error below. Can you help me again?

evaluate call to endorser returned error: error validating proposal: access denied: channel [mychannel] creator org [Org1MSP]

[bestbeforetoday]

That error suggests some authentication error at the peer end. Typically either the creator certificate or the signature is invalid. Check the peer logs for additional information.

[bestbeforetoday]

Note that I added a couple of extra things to check to my previous comment

The .NET libraries should have mechanisms for verifying that a (private key) signature over a message is valid for the corresponding public key. Google found me this:

https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.ecdsa.verifydata

It seems that the Node (currently using @noble/curves) and Java (currently using Bouncy Castle) ECDSA signing implementations use different approaches by default. Java introduces additional randomisation into the signature generation while Node produces deterministic results. I'm not sure if either of these approaches is particularly preferable. This seems to be a relevant document:

https://www.rfc-editor.org/rfc/rfc6979.html

[Varorbc]

I also used Bouncy Castle to port ECPrivateKeySigner.java, but the signature invalid. Are there any other special points to pay attention to?

[bestbeforetoday]

Everything about the signature generation that I can think of right now is in the post above.

Be careful that you are creating the signature using the private key, and then verifying using the certificate / public key. Also be sure you are specifying the correct hash algorithm for both the signing and verification. Note that the Java implementation passes a pre-computed digest (SHA-256 hash of the message) to the signer, and signs using NONEwithECDSA. If you are passing the whole message to the signer then you should use SHA256withECDSA. The signature verification in the unit tests is done using SHA256withECDSA.

[Varorbc]

This is my ported code, private key, certificate, because I am not an encryption expert, can you help me see why the signature is invalid?

PRIVATE KEY

-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgpTzdfAxUixQvue86
crrVOpYcXY84sbpxjMIitf7bdgahRANCAASkt/bPiLFVQyL/f0GQeqOcHPwZEX7U
1oKpEqiJlNjaItI3mZkfUvBNtxGWy5XYfEAgxVdKJfySZZAByZ0ASvpR
-----END PRIVATE KEY-----

CERTIFICATE

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

ECPrivateKeySigner

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;

namespace Fabric;

public class ECPrivateKeySigner
{
    private const string ALGORITHM_NAME = "NONEwithECDSA";

    private readonly PrivateKeySigner _signer;
    private readonly BigInteger _curveN;
    private readonly BigInteger _halfCurveN;

    public ECPrivateKeySigner(string privateKey)
    {
        var stringReader = new StringReader(privateKey);
        var pemReader = new PemReader(stringReader);
        var obj = pemReader.ReadObject();
        if (obj is ECPrivateKeyParameters ecPrivateKey)
        {
            _signer = new PrivateKeySigner(ecPrivateKey, ALGORITHM_NAME);

            _curveN = ecPrivateKey.Parameters.N;
            _halfCurveN = _curveN.Divide(BigInteger.Two);
        }
        else
        {
            throw new NotSupportedException("Unsupported private key type");
        }
    }

    public byte[] Sign(byte[] digest)
    {
        var rawSignature = _signer.Sign(digest);
        var signature = ECSignature.FromBytes(rawSignature);
        signature = PreventMalleability(signature);
        return signature.GetBytes();
    }

    private ECSignature PreventMalleability(ECSignature signature)
    {
        BigInteger s = signature.GetS().Value;
        if (s.CompareTo(_halfCurveN) > 0)
        {
            s = _curveN.Subtract(s);
            return new ECSignature(signature.GetR(), new DerInteger(s));
        }
        return signature;
    }
}

public class ECSignature
{
    private readonly DerInteger r;
    private readonly DerInteger s;

    public ECSignature(DerInteger r, DerInteger s)
    {
        this.r = r;
        this.s = s;
    }

    public static ECSignature FromBytes(byte[] derSignature)
    {
        try
        {
            using (MemoryStream inStream = new MemoryStream(derSignature))
            {
                using (Asn1InputStream asnInputStream = new Asn1InputStream(inStream))
                {
                    Asn1Object asn1 = asnInputStream.ReadObject();

                    if (!(asn1 is DerSequence))
                    {
                        throw new GeneralSecurityException("Invalid signature type: " + asn1.GetType().Name);
                    }

                    DerSequence asn1Sequence = (DerSequence)asn1;
                    var signatureParts = asn1Sequence.OfType<DerInteger>().ToList();
                    if (signatureParts.Count != 2)
                    {
                        throw new GeneralSecurityException("Invalid signature. Expected 2 values but got " + signatureParts.Count);
                    }

                    return new ECSignature(signatureParts[0], signatureParts[1]);
                }
            }
        }
        catch (IOException e)
        {
            throw new IOException("IOException occurred while reading from MemoryStream.", e);
        }
    }

    public DerInteger GetR()
    {
        return r;
    }

    public DerInteger GetS()
    {
        return s;
    }

    public byte[] GetBytes()
    {
        using (var bytesOut = new MemoryStream())
        {
            var sequence = new DerSequenceGenerator(bytesOut);
            sequence.AddObject(r);
            sequence.AddObject(s);
            sequence.Dispose();
            return bytesOut.ToArray();
        }
    }
}

public class PrivateKeySigner
{
    private readonly ECPrivateKeyParameters privateKey;
    private readonly string algorithm;

    public PrivateKeySigner(ECPrivateKeyParameters privateKey, string algorithm)
    {
        this.privateKey = privateKey;
        this.algorithm = algorithm;
    }

    public byte[] Sign(byte[] digest)
    {
        var signer = SignerUtilities.GetSigner(algorithm);
        signer.Init(true, privateKey);
        signer.BlockUpdate(digest, 0, digest.Length);
        return signer.GenerateSignature();
    }
}

[bestbeforetoday]

I don't work with C#. At first glance the code looks reasonable, although I don't see how you are creating the message digest or how you are doing signature verification. I would suggest a unit test that:

1. Generates a public/private key pair.
2. Creates a signature for a message using the private key.
3. Verifies the signature over the message using the public key.

Start with an absolutely minimal implementation that just uses the Bouncy Castle (or .NET) APIs to create the signature. Check it works, then gradually extend the implementation to deal with malleability, handle certificates and PEM parsing. As you build out the implementation step-by-step, hopefully you will identify the step that is causing an invalid signature.

[Varorbc]

@bestbeforetoday Thank you very much for your help. My problem has been solved. There is nothing wrong with the signature itself, I created the wrong message digest

[bestbeforetoday]

Reopening as this is a good discussion to keep visible as a reference for others.