COMPARISON
Locke vs Microsoft Purview Information Protection
Microsoft Purview (formerly Azure Information Protection) is a mature DLP and labelling platform built deep into Microsoft 365 — strong at classifying and protecting documents, email, Teams, and SharePoint, with AI controls now built into its AI Hub. Its reach stops at the Microsoft 365 boundary, though. A prompt typed into ChatGPT or Claude sits outside it, and pasting a labelled Word document into a competitor's AI tool bypasses Purview entirely.
When Microsoft Purview Information Protection fits
- Your organisation is deeply invested in Microsoft 365 and needs sensitivity labelling, encryption, and rights management across email, Teams, SharePoint, and Office documents.
- You need centralised policy management, compliance manager dashboards, and eDiscovery that spans the full Microsoft 365 estate.
- Your primary AI governance concern is Microsoft Copilot — Purview's AI Hub provides prompt auditing and policy enforcement within the M365 boundary.
When Locke fits
- Employees use browser-based AI tools outside the Microsoft 365 boundary — ChatGPT, Claude, Gemini, Grok, Perplexity — where Purview has no reach.
- You need a control that acts at the moment of composition, before text is submitted, rather than after the document is classified.
- You want a zero-knowledge control: no prompt content is logged by the privacy vendor, unlike Purview's audit logs which capture prompt text.
Side-by-side
| Dimension | Locke | Microsoft Purview |
|---|---|---|
| Coverage of non-Microsoft AI tools | Works on any browser-based AI chat — ChatGPT, Claude, Gemini, and others. | Limited to Microsoft 365 apps and Copilot; no coverage of competitor AI tools. |
| Where controls operate | On the device, inside the browser, at the moment of composition. | At the Microsoft 365 layer — documents, email, Teams, SharePoint. |
| Sensitive-data visibility to the vendor | Zero-knowledge: Sonomos never sees prompt content. | Purview audit logs capture prompt text and policy matches — visible to your admin. |
| Rollout effort | Per-user, on-device install (Locke desktop app coming soon) — days to deploy at scale. | Deep integration with M365 tenant configuration — weeks to months. |
| Best for | Preventing sensitive data from reaching any browser-based AI tool. | Classifying, labelling, and protecting documents and communications within M365. |
Bottom line
Purview and Locke protect different surfaces, and work well together. Purview governs the Microsoft 365 estate — documents, email, Teams, Copilot. Locke governs the moment someone opens any other AI tool. The paste into ChatGPT from a labelled Word document is exactly the gap Purview can't close — and exactly why Locke exists.
