Cert Companion (VS Code)

Decode X.509 certificates (PEM/CRT/CER/DER) — subject, issuer, validity window, SHA-256 fingerprint, and an expiry check — no data leaves your editor.

v0.1, pilot. Part of the Gap Hunter Labs VS Code workstream porting selected niches from the IntelliJ-family catalog. The IntelliJ-family Cert Companion also decodes .jks/.p12/.pfx keystores — this version doesn't (yet): Node has no built-in PKCS12/JKS reader, and adding one means either a third-party dependency or shelling out to OpenSSL, neither done here. The command tells you plainly when you hit that gap instead of failing silently.

What it does

Command: Cert Companion: Decode Certificate File — run it with a .pem/.crt/.cer/.der file open (or pick one from a file dialog). Multi-certificate PEM bundles decode one card per certificate, not a squeezed single view. Output goes to an output channel:

=== Certificate [#1](https://github.com/GapHunterLabs/vscode-cert-companion/issues/1) ===
Subject:      CN=example.test, O=..., L=Test, ST=Test, C=US
Issuer:       CN=example.test, ...
Serial:       12:34:...
Valid from:   2026-09-07T07:00:07.000Z
Valid to:     2036-09-04T07:00:07.000Z
SHA-256 fpr:  AB:CD:...
Status:       valid

Uses Node's built-in node:crypto X509Certificate — no third-party crypto library, same "standard-library-only" philosophy as the IntelliJ-family version (JDK-only there).

Privacy

See PRIVACY.md — zero network calls, decoding happens entirely in your editor process.

Development

npm install
npm run compile   # or: npm run watch
npm test

Press F5 (with this folder open) to launch an Extension Development Host. To build an installable package without publishing:

npx @vscode/vsce package

License

Apache License 2.0 — see LICENSE.