Plugin signing

HarborClient plugins can be signed with an Ed25519 key so installers can verify that plugin files match a publisher's signature. Signing is optional for third-party plugins; unsigned plugins may show a warning when enabled in HarborClient.

Authors listed in HarborClient's trusted publisher registry must sign every plugin they publish. HarborClient rejects installs that claim a trusted author name without a valid signature.

To discuss becoming a trusted publisher, email contact@harborclient.com.

The @harborclient/sdk/signing module provides programmatic signing and verification, plus CLI tools for release workflows.

Generate a key pair

Use OpenSSL to create an Ed25519 private key and extract the public key:

openssl genpkey -algorithm ED25519 -out plugin-signing.pem
openssl pkey -in plugin-signing.pem -pubout -out plugin-signing.pub.pem

Keep the private key offline or in CI secrets. Distribute only the public key to users or verification tooling.

Sign a plugin directory

From your plugin project (after building entry files into dist/):

pnpm plugin:sign -- --dir . --private-key ../plugin-signing.pem --key-id my-publisher

Or use the published CLI binaries:

pnpm exec hc-plugin-sign --dir . --private-key ../plugin-signing.pem --key-id my-publisher

This writes signature.json at the plugin root. The file lists every hashed file (excluding signature.json, .git/, node_modules/, and .DS_Store) and an Ed25519 signature over a canonical JSON payload.

Commit signature.json to your repository when users install from git, or ship it inside the .hcp archive for file-based installs.

Verify a plugin directory

pnpm plugin:verify -- --dir . --public-key ../plugin-signing.pub.pem

Add --allow-unsigned to exit successfully when signature.json is absent (useful in CI before signing is enforced).

Exit codes:

Code	Meaning
0	Signature valid (or unsigned with --allow-unsigned)
1	CLI usage error
2	Sign failure
3	Invalid signature or tampered files
4	Unsigned (without --allow-unsigned)

Programmatic API

Import from @harborclient/sdk/signing:

import { readFileSync } from 'node:fs';
import { signPlugin, verifyPlugin } from '@harborclient/sdk/signing';

await signPlugin({
  pluginDir: './my-plugin',
  privateKeyPem: readFileSync('./plugin-signing.pem', 'utf8'),
  keyId: 'my-publisher'
});

const result = await verifyPlugin({
  pluginDir: './my-plugin',
  trustedPublicKeysPem: [readFileSync('./plugin-signing.pub.pem', 'utf8')]
});

if (result.status !== 'valid') {
  throw new Error(result.error ?? result.status);
}

Exported helpers useful for HarborClient runtime integration:

• collectPluginFiles(pluginDir) — sorted SHA-256 inventory
• readPluginSignature(pluginDir) — parse signature.json when present
• PLUGIN_SIGNATURE_FILENAME — 'signature.json'

signature.json format

{
  "schemaVersion": 1,
  "pluginId": "com.example.my-plugin",
  "pluginVersion": "1.0.0",
  "algorithm": "Ed25519",
  "keyId": "my-publisher",
  "files": [
    { "path": "dist/renderer.js", "sha256": "..." },
    { "path": "manifest.json", "sha256": "..." }
  ],
  "signature": "<base64>"
}

The signed payload includes schemaVersion, pluginId, pluginVersion, algorithm, optional keyId, and the sorted files array. The signature field itself is excluded from the payload.

Marketplace plugins

Official HarborClient plugins can commit signature.json alongside manifest.json in their GitHub repositories. HarborClient verifies signatures at install time against the trusted publisher registry.