Show HN: PII-Shield – Log Sanitization Sidecar with JSON Integrity (Go, Entropy)

[aragoss]

What PII-Shield does: It's a K8s sidecar (or CLI tool) that pipes application logs, detects secrets using Shannon entropy (catching unknown keys like "sk-live-..." without predefined patterns), and redacts them deterministically using HMAC.

Why deterministic? So that "pass123" always hashes to the same "[HIDDEN:a1b2c]", allowing QA/Devs to correlate errors without seeing the raw data.

Key features: 1. JSON Integrity: It parses JSON, sanitizes values, and rebuilds it. It guarantees valid JSON output for your SIEM (ELK/Datadog). 2. Entropy Detection: Uses context-aware entropy analysis to catch high-randomness strings. 3. Fail-Open: Designed as a transparent pipe wrapper to preserve app uptime.

The project is open-source (Apache 2.0).

Repo: https://github.com/aragossa/pii-shield Docs: https://pii-shield.gitbook.io/docs/

I'd love your feedback on the entropy/threshold logic!

[aragoss]

Update: Seeing some folks pulling the Docker image. Just a heads up — the default entropy threshold is 3.8, which is tuned for API keys. If you are testing with simple words like 'test', it might not catch them (by design). Check the README for tweaking PII_ENTROPY_THRESHOLD.

[maxbond]

Cool project!

- Wouldn't this censor UUIDs? I want UUIDs to remain in my logs.

- The never "PII Shield" makes me think this would censor entities like names or social security numbers, rather than secrets. Not a big deal though.

[aragoss]

Thanks!

UUIDs: By default—no. Since UUIDs are Hex (limited charset 0-f), they have lower entropy than Base64 secrets. The threshold is tuned to sit safely above UUIDs but below API keys.

Naming: You are totally right. Currently, it focuses on "high-entropy PII" (passwords, auth tokens, session IDs) rather than names or SSNs. "Secrets Shield" might have been more precise, but naming is hard :)

[gritspants]

Thanks for this. Showed some of my colleagues who thought it was cool also.

[aragoss]

Thank you! Hearing that it's being shared is the best kind of validation.

If your team ends up trying it out and has any feature requests (or catches any edge cases), I’d love to hear them!

[johnthescott]

bravo. you are off to a good start.

[aragoss]

Thank you! Appreciate the kind words.