Can I trust Proton Authenticator & 2FA?
This scan is more than 90 days old.
This app did not meet one of the trust checks that applied to it, with no red flags.
- Best for
- General use with standard privacy expectations
- What it means for you
- The build may include code to pass usage data and device activity to the app developer and any integrated services. Review the category summary below for details.
- Main concern
- SSO callback accepts unvalidated token from any co-installed app — potential hijack
- The developer's description
- Private, end-to-end encrypted two-factor authentication app by Proton. Open-source, offline-capable, and backed by Swiss privacy laws. Syncs 2FA codes securely across devices without requiring a Proton account.
- Third-party services
- 13
- Findings rated low or higher
- 2
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Full findings
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Trust checks
Secure by Design
One criterion not metSecurity gaps detected
Why this result
This check looks for security issues at high severity or above in the code of this build, and at least one was recorded. Issues of this kind include a credential or token another app on the device can reach, sensitive data stored without protection, and network paths that expose information in transit.
Data Minimization
StrongTracking done right
Why this result
The check looks at analytics and attribution code for companies other than the developer: the data it reads, the companies named in code as recipients, and whether a consent step runs before that code. In this build, either no such code was recorded, or a consent step runs before it and the app's own disclosures describe the collection.
This app contains no third-party analytics, advertising, or behavioral tracking services of any kind. The only data collection code is optional crash reporting and usage telemetry that the app includes code to send exclusively to Proton's own servers, with no code naming outside companies as a destination. You can turn telemetry off at any time in the app's settings. There is no advertising ID collection, no pre-consent data gathering, and no opt-out barriers.
Manifest Mismatch
StrongEverything visible
Why this result
The check compares the app's privacy disclosures against what the code does: the data categories collected, the companies named in code as their recipients, and the identifiers attached to each. The comparison covers the store listing, the in-app privacy text and any privacy manifest shipped in the build. Every claim compared matched the code here.
The app's actual data behavior matches what a transparent privacy policy for a Proton product would describe. The crash report code names a Proton-operated relay as its destination rather than a third-party service directly, telemetry is optional and user-controlled, and no undisclosed data collection was found. The crash reporting connection key is visible in the app file but can only be used to submit reports — not to access anyone else's data. No gap between disclosed behavior and code behavior was found.
User Control
StrongNo lock-in
Why this result
The check looks for a way to export the data an account has accumulated and a way to delete the account itself. In this build, either both were found, or the app has no account of its own and keeps its data on the device. For an app without an account, the developer has no server-side copy to export or delete, and deleting the app removes the data in its own storage.
The app includes a built-in export feature that lets you save all your two-factor accounts to a file you control, protected with a password you choose. Account deletion is available from within the app. There are no proprietary formats or artificial barriers that would prevent you from moving your accounts to another authenticator app.
Truly Local
StrongStays on the device
Why this result
This app presents itself as working offline or on the device alone. The check looks for any code written to send personal data to a server, including analytics, crash reporting and advertising code. None was recorded in this build.
Your two-factor authentication secrets are stored encrypted on your device using Android's hardware security chip — they never leave your phone in readable form. Any server communication in the code names only Proton's own infrastructure as the destination. Crash reports are addressed in code to a Proton-operated server rather than to a third-party crash service, so the build contains no code to send them to outside companies. Google cloud backup is explicitly disabled, so the build contains no backup code path that would upload your secrets to Google.
Strengths
- SPKI leaf certificate pinning with 10 hardcoded pins active in production
- Certificate Transparency enforcement via appmattus library
- AES-256-GCM Android Keystore encryption for all TOTP secrets and session tokens
- Auto backup disabled — TOTP secrets are excluded from Google cloud backup
- No third-party analytics, advertising, or tracking SDKs
- First-party telemetry only with explicit user opt-out toggle
- SRP authentication via Go native crypto: the build includes no code to transmit passwords to the server
- Minimal justified permissions — no location, contacts, SMS, or audio access
- GMS usage limited to FIDO2 hardware key support only
- Rust crypto core with integrity checksum validation against library substitution
What the app contains
13 services
Third-party services the scan names in the build:
- Proton Core
- OkHttp3
- Retrofit2
- Sentry Android
- appmattus Certificate Transparency
- GOpenPGP (Go Mobile)
- ZXing
- Google Play Services FIDO
- AndroidX Biometric
- Coil
- Lottie
- WorkManager
- Room
Libraries
| Library | Version | Advisory |
|---|---|---|
| Room | not recorded | none confirmed |
| Lottie | not recorded | none confirmed |
| Google Sign-In | 12451000 | none confirmed |
| Google Play Services | 12451000 | none confirmed |
| Material Components | not recorded | none confirmed |
| Play Core | not recorded | none confirmed |
| Dagger | not recorded | none confirmed |
| Firebase | 12451000 | none confirmed |
| Protocol Buffers | not recorded | none confirmed |
| ZXing | not recorded | none confirmed |
Show all 17 librariesShow fewer
Method and limits
Static analysis: the decompiled code, manifest and resources of this build, read file by file. Network traffic at run time is established by a capture of the running app.
- Files decompiled
- 19,607
- Scan date
- 26 June 2026
Corrections
No correction is published for this app.
Developer response
No response is published for this app.
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