Everything your security review will ask about Locke.

Locke inspects prompts and files on the user's own device and masks sensitive data before it reaches an AI tool. Sonomos never receives that content. This page sets out what does reach us, who processes it, and where we stand today.

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1 · Architecture

Architecture and data flow

Locke is a desktop application (Windows and Linux in Early Access, macOS planned) with a companion browser extension. Detection and masking run entirely on the device. No cloud model, inference API or remote classifier is involved.

1
Capture, on the device. On supported AI websites, the Locke Extension holds the request inside the page when the user submits it and hands it to the desktop app over native messaging. The extension's only endpoint is the Locke app on the same machine (127.0.0.1). Command-line agents, scripts and SDK calls to AI APIs are captured by a proxy that runs on the user's own machine.
2
Detection, on the device. Checksum-validated pattern detectors and on-device machine-learning models find sensitive values in memory.
3
One-way masking, on the device. Detected values are replaced with non-reversible placeholders. There is no key that can reconstruct the original. Reversible tokenization is planned after Locke 1.0 and is not part of it.
4
Onward to the provider the user chose. The masked request continues directly to the AI provider over a standard, fully verified TLS connection. It does not pass through Sonomos. If the extension gets no verdict from the app, the request is blocked rather than sent unscreened.

Scoped interception and the local certificate. The browser extension screens supported AI sites. When desktop capture is active, discovery can decrypt and inspect initial requests to eligible unknown HTTPS destinations that reach the local proxy, including services later classified as non-AI. Discovery's classification limits do not cap all decryption on an already-open intercepted connection. Platform, routing rules and unsupported connections affect scope; AI-service controls apply after classification. See the Locke Privacy Policy for details. Locke creates local certificate material for its gateway. It is not shared across users or devices, the private key is never transmitted, and trusting the local root is an explicit device-level decision.

What crosses the network to Sonomos. A small, fixed set of requests, none carrying content: sign-in, a periodic licence check, settings sync and update checks, plus a standard TLS certificate-revocation check. Crash reports and support messages travel only if the user chooses to send them. Locke has no behavioural telemetry or usage analytics channel.

2 · Data inventory

What lives where

Data Locke handles, where it lives, and whether it is sent to Sonomos
Data	Where it lives	Sent to Sonomos?
Prompts, pasted text and files Locke inspects	Inspected in memory on the user's device and not written to disk by Locke. The masked request then goes straight from the device to the AI provider the user chose.	Sent to Sonomos: Never
Detected sensitive values	Replaced on the device with one-way placeholders before the request leaves it.	Sent to Sonomos: Never
Detection results	A local database on the device, as metadata only: type, count, timestamp and match length, never the matched text.	Sent to Sonomos: Never, not even in aggregate
Compliance and activity reports	Generated locally from local data; exported or deleted by the user.	Sent to Sonomos: Never
Local certificate material for the gateway	Created on the device. The private key stays on the machine.	Sent to Sonomos: Never
Sonomos account (name, email address, session activity)	Held by our authentication provider, Clerk. Signing in is required to use Locke.	Sent to Sonomos: Yes
Licence check (account identifier and plan)	Repeated periodically while the desktop app runs. Like any request it discloses an IP address. We keep current subscription status, not a usage history.	Sent to Sonomos: Yes. No content, detection or usage data
Settings (AI services monitored, categories enabled)	Synced to the user's account in our hosted database (Supabase), so settings follow the user and, on the Teams plan, an administrator can apply a policy.	Sent to Sonomos: Yes. Configuration only, no content
Billing records (Teams)	Stripe. Card data is collected by Stripe directly; we never hold it.	Sent to Sonomos: Yes, via Stripe
Crash reports and support messages	Never automatic. The user sees the exact contents first. Crash reports carry the error and a stack trace with file paths and email addresses stripped, plus app version and platform.	Sent to Sonomos: Only if the user sends it
Update checks	The desktop app checks our release channel. The extension is updated by the browser marketplace it was installed from.	Sent to Sonomos: Update check only

Source: the Locke Privacy Policy, Sections 2–7, which is the binding statement of what Locke sends us. If a future release changes that list, the policy is updated before the release ships.

3 · Sub-processors

Who processes data on our behalf

None of these providers receives the content Locke inspects, because Sonomos never has it. The AI provider a user sends a masked request to is chosen and contracted by the user or their organisation; it is not a Sonomos sub-processor.

For the Locke product

Clerk

Authentication for the Locke desktop app.

Name, email address and session activity.

Supabase

Hosted database for Locke account and settings data.

Account identifier and synced settings. No content.

Stripe

Subscription billing.

Name, email address and payment data. Card data goes to Stripe directly.

For our websites and correspondence

Supabase: Website authentication and database (email address, user ID).
Resend: Transactional email and routing contact-form messages.
Cloudflare: Hosting, content delivery, edge security and contact-form delivery.
Simple Analytics: Cookieless, aggregate website analytics.
Google Workspace: Our company email, for receiving and answering your correspondence.

Sources: Locke Privacy Policy Sections 3 and 5; Website Privacy Policy Section 6.

4 · Data processing

Data processing and DPAs

Sonomos never receives the content Locke inspects, so there is no content for a data processing agreement to govern. The personal data Sonomos does process because of Locke is limited to the account, licensing, billing and synced-settings data described in the Locke Privacy Policy.

For the Teams plan, contact us to request a data processing agreement covering that account and settings data. Tell us what your organisation needs and we will work through it with you.

5 · HIPAA

HIPAA and business associate agreements

Locke inspects content on the user's device. Sonomos does not create, receive, maintain or transmit the content Locke inspects. Because of that, it is Sonomos's position that we do not expect to act as a business associate (as defined in 45 CFR 160.103) with respect to that content.

We will still review a BAA request: contact us. This is our position, not legal advice: whether a business associate relationship exists depends on your organisation's facts, and we recommend your counsel confirm it. No software is HIPAA compliant on its own, and Locke's detection is probabilistic and can miss things. A BAA with the AI provider you send masked requests to is a matter between your organisation and that provider.

More context: Locke for healthcare · What a BAA is

7 · Assurance

Certifications and audits: where we are

Not yet. Locke is pre-1.0 and in Early Access. It has not yet undergone a SOC 2 Type II audit or a formal third-party security audit. Both are on our roadmap. Releases are signed today: the Windows installer is Authenticode-signed by Sonomos, Inc., and Linux is published as immutable, versioned .deb and .rpm packages.

What is published today:

Reproducible benchmarks, not certifications. You can run the same benchmarks we do, from the repositories.
Independent scans of sonomos.ai (a Blacklight privacy scan, a Qualys SSL Labs report and a published security.txt), linked from our Security page. These cover the website, not the Locke app.
Detailed architecture, threat model and compliance-readiness documentation in the Sonomos Trust Center, access-restricted during the beta; we grant access for security reviews on request.

Our Trust & Transparency page keeps the honest list of what is not yet true.

8 · Threat model

What local processing does not protect against

Malware, keyloggers, screen capture, unauthorised physical access or a compromised operating system. Locke's protection is bounded by the security of the device it runs on.
Data that was already sent to a third party before Locke was in place.
Missed detections. Detection uses pattern matching and on-device machine learning, and can produce both false positives and false negatives.
Unsupported request types and capture paths, including prompts submitted from search engines the extension loads on but does not screen. Desktop wrapper apps are recognized and screened, subject to app, platform and settings.
What the AI provider does with the masked request. That request is governed by the provider's own terms; any DPA or BAA for the AI service itself is between your organisation and that provider.

Using Locke does not by itself constitute compliance with HIPAA, GDPR, GLBA or any other framework. For the full security model, including scoped interception, the hardened app and the build process, see Locke Security.

Request the security review pack

Email us your organisation and what your review needs: Trust Center access, a DPA, a BAA review or anything else. Send us your security questionnaire and we will work through it with you.

Email info@sonomos.ai Trust Center

Found a vulnerability instead? See how to report it.

See Locke's local compliance reports