Invalid Signature Error with .NET Core and Arduino

[erhankiyakk]

Describe the problem

I am encountering an "invalid signature" error while working with .NET Core and Arduino. Here's how I am performing the signing process:

`SignCode

    string privateKeyPem = @"-----BEGIN RSA PRIVATE KEY-----
    MIIEogIBAAKCAQEAyh9OfQnmto6A7ext/c2+mszLlmhiA7SnhPlBhrecvpaQB3mH
    zp1e8B01S1sCC1HuGphDP4yRmJJK/EwWDlPrqKZg5xwF9N7nam83djPyY6hkH1NJ
    boBe6Zu9vyOV79YpxxPaYDRmgXG5u46OCjVZctdHGWC9LDOzVeDlPTkgoqG4lRSQ
    NRFlkc9cNh7BZt1oj/Th/ZEMhFTDcSlZTx0F8nz1J6FrLH1lt6JfHxBrvzTk89pu
    kolkm8D6X+W0eEm+zJsk0fSGfvLpu+De28BFHrxvLSrguVJUzZalqjqhm2hFP6uh
    0gnmb8LeKiDLdGkySPoY0NcaJiLNmJrVEj8rNwIDAQABAoIBAF1eLOGx6zO1jHVb
    3Et7+WqE5B7sxSo1D5VrlwtmUi/wWUQ6rbOSGsMMmwveVIlqJXV/lMEMbE1wdtcp
    Rp8DwT687NKVrWK6fWg7TAF8aaIDrYyS6r7y6eU8HmDnTWHnKpFd6Gi8jAWLxWKQ
    railkFZuf9eHSpvaniMzqnGnrB2zh81wXvwP3/bImdo/hRP8r8V48HCOlEOhMWAj
    SewAcUkHmVSSMQqqLHrneAOpdiBneq281l2EEeKJl58R9OD/jx36Tc5Oyi0i2ucc
    x2n5cU653B3Eib4dKDRratuP7G289Pv74+fZreFUqmvVK6tj/08ftcsnUXy/eEIL
    9i3vhtECgYEA/Bw93ioxW6Xpedyds6yHQfhkE/0rnAvhjZsRqrNCii08LHLPd9fo
    xLvKkqEdlBkZc+i1RzMM6YsuRWKi/m9P8vvqK5cpOkSnKdtozUNHeNHBdKczydzP
    DGt0GF5drUDPUmI0KkpupiJFNftXFkbNpYc9P3EiGZrYXOKWaC32O+UCgYEAzT2g
    qEwhz2H9uZnX657BNP/5vuLki2SZhlxnUjTfOZSj0Z4cb2Qc1H09GFm+d5JfvaVA
    0kA6lDVCk1y7yTSWsI6AeJ/FmCFbzIKxjIHRtilE07rYF+eIL0FhFRwlrVNUlV3S
    qI91DH35ODhDH+gER/t3ovoW0R8puTwPwS7acOsCgYBUDLJPk+96p3iMKRHmadl6
    E+6Bf4D/eDKNPCqKp1LCsEwEYY5rXO78T8M8WTx8OFX0/5sYDpv6bG1Tsou2mbOk
    xXmPaMjU5Th5yu1IqWp1jDCbzHaGkPfyIwzEZwmCDj5QL+9GPiRffMNoONAS3C4J
    RmoT8Yq10JrbdKtCNjiGRQKBgF6zsQ33EyK99HVPp3HxLvVlp7eMuigXoz98I7Cq
    9NV84Jo4eqZra2Ig56/0uQ4zXDoFpoNdX6pDaRTWFVAiE+Yj2uPN1T79JX6YT5Sl
    0j5bjIamEE/3Zb9oS4OSGVCAwuapBCsDBt9cwUJPs6llRZRxVCK/gwe7eWUfcaWS
    GPlBAoGAVIcM+d4x8NBOSYzBrUWazj2+5eiB8v1SvIMonm0zpeGfTByxoK3CGvTB
    ECz65EZrzBVHb1QYLV0ZUK17azsO7r3Y3rL7PCj6t2ADIUwdO0TtRO5Icy37i/to
    uEnKrszlB/alkWVhkfKaq9GGFhfQkdsAj+0eMALy1XUA9ksUV0Y=
    -----END RSA PRIVATE KEY-----";
    string commandLine = "\"{runtime.tools.avrdude.path}/bin/avrdude\" \"-C{runtime.tools.avrdude.path}/etc/avrdude.conf\" -v  -patmega328p -carduino \"-P{serial.port}\" -b115200 -D \"-Uflash:w:{build.path}/{build.project_name}.hex:i\"";

    using (RSA rsa = RSA.Create())
    {
        rsa.ImportFromPem(privateKeyPem.ToCharArray());

        using (SHA256 sha256 = SHA256.Create())
        {
            byte[] dataBytes = Encoding.UTF8.GetBytes(commandLine);
            byte[] hash = sha256.ComputeHash(dataBytes);
            byte[] signatureBytes = rsa.SignHash(hash, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
            return Convert.ToBase64String(signatureBytes);
        }
    }

`

Additionally, I've added the following to the config.ini file:
signatureKey = -----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyh9OfQnmto6A7ext/c2+mszLlmhiA7SnhPlBhrecvpaQB3mHzp1e8B01S1sCC1HuGphDP4yRmJJK/EwWDlPrqKZg5xwF9N7nam83djPyY6hkH1NJboBe6Zu9vyOV79YpxxPaYDRmgXG5u46OCjVZctdHGWC9LDOzVeDlPTkgoqG4lRSQNRFlkc9cNh7BZt1oj/Th/ZEMhFTDcSlZTx0F8nz1J6FrLH1lt6JfHxBrvzTk89pukolkm8D6X+W0eEm+zJsk0fSGfvLpu+De28BFHrxvLSrguVJUzZalqjqhm2hFP6uh0gnmb8LeKiDLdGkySPoY0NcaJiLNmJrVEj8rNwIDAQAB\n-----END PUBLIC KEY-----

I'm attempting to upload the data with this configuration:
`

    let data = {
        "port": port,
        "data": res.Hex,
        "hex": res.Hex,
        "filename": res.Filename,
        "network": res.Network,
        "commandline": res.Commandline,
        "board": res.Board,
        "serial": true,
        "signature": res.Signature
    };
    $.ajax({
        url: "http://localhost:8991/upload",
        data: JSON.stringify(data),
        success: function (t) {
            console.log(t);     
        },
        error: function (t) {
            console.log(t);
            console.log(t.responseText);
        }
    });

`

However, I keep receiving an "invalid signature" error. How can I resolve this issue?

To reproduce

1. Setup Environment: Ensure you have a .NET Core environment set up for interfacing with Arduino.
2. Add Code for Signature Generation: Implement the SignCode function in your .NET Core application as provided in the original description. This function generates a signature using RSA private key.
3. Configure config.ini: Add the public key to your config.ini file as indicated in the original description.
4. Prepare Data for Upload: Construct the data object in your code with necessary fields such as port, data, hex, filename, network, commandline, board, serial, and signature.
5. Execute AJAX Request: Perform an AJAX request to http://localhost:8991/upload with the data object.
6. Observe Error: The response received is an "invalid signature" error.

Expected behavior

• The .NET Core application successfully generates a valid digital signature using the RSA private key.
• The data object, along with the generated signature, is sent to the server via AJAX.
• The server validates the signature against the public key provided in the config.ini file.
• Upon successful validation, the server accepts the upload without returning an "invalid signature" error.
• The entire process completes smoothly, allowing for the intended data transfer between the .NET Core application and the server.

Arduino Create Agent version

Last Version

Operating system

Windows

Operating system version

Windows 11

Browser

Chrome

Browser version

Last version

Additional context

No response

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the latest version
• My report contains all necessary details

[dido18]

Hi @erhankiyakk thanks for the report.

We recently released the agent 1.7.0 that contains a fix for the signatureKey format.

Could you test it with the new version?
As you can read from the updated wiki page, the public key must be set in the config.ini file using this format:

signatureKey = `-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtHP52M8dCYDGaC4UaOvU
cfLqhteGX75EnbXMr6iOg7r7Of+doFV+Ee233Ly/di15CXaju3EpgUka5QSu6z2m
4sne32aGw6T/eggY636CKcRHFPFjLmXX0CHq+Evg3E4g8W7Yslo2qu1SP3ySZCqe
VpZHSeehlxFPpQKWXa1YiNF0gWh3cNQ0wneOsJ+ndShSuQ5C2YnSEoeoiEGVFOS0
evX4GEdadudGBjHQUKjhj+k3Ydaz014aIIC7CUVkQog9B7vpB+znHJH/gCl9DqYO
4mjPfHG4c5ppNu455hEe75R5q9bPc7TjBA3jpZsdrBY05lX2Q2nAQgSYIHpf78xl
7wIDAQAB
-----END PUBLIC KEY-----`

[dido18]

I close the issue.
Feel free to reopen it if the problem persists 💯