Proton Authenticator Security & Privacy Scorecard

Proton Authenticator

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.

What This Means for You

Your two-factor authentication codes stay encrypted and stored on your devices, and Proton sends nothing to advertising networks or tracking companies.

Recommendation: Very Secure

Excellent for secure two-factor authentication. Open-source, strongly encrypted with verified server connections, and sends zero tracking data. Works offline without a Proton account.

Best For: Privacy-conscious users and those managing sensitive 2FA accounts who want a no-tracking, strongly encrypted authenticator

Key Findings

Data Security - 1 finding (1 low)

Network Security - 0 findings

Code Safety - 1 finding (1 high)

Privacy - 1 finding (1 info)

Privacy Concerns

What Data is Collected

• Account information: If you sign in with a Proton account, your login details are processed to sync your codes across devices. Your password is processed on your device and never sent to a server.
• Two-factor codes and secrets: Stored and encrypted on your device only. These stay on your device.
• Diagnostic reports: Anonymous crash and error information may be sent to Proton's own servers when the app encounters a problem. Personal identifiers are excluded from these reports, and you can opt out.
• Camera: Accessed on your device only when scanning QR codes to add new accounts.

Third-Party Data Sharing

No third-party data sharing was identified in this analysis.

Understanding the Scores

Security: 88/100
Privacy: 100/100

Security Breakdown

• Data Security: 96/100 - Your 2FA secrets are stored using strong on-device encryption backed by your device's hardware security, and protected from cloud backup access.
• Network Security: 100/100 - All communication with Proton's servers is protected by multiple independent layers of connection verification.
• Code Safety: 85/100 - The app uses a verified cryptographic engine with integrity checking. The single sign-on login flow has one area that could be hardened against interference from other apps on your device.

Privacy Breakdown

• Data Collection: 100/100 - No analytics, advertising, or behavioral tracking data leaves your device. The app operates fully offline with zero data sent to tracking or advertising companies.
• Data Sharing: 100/100 - Your data is not shared with any third parties. When crash reports are sent, they go exclusively through Proton's own infrastructure.
• User Control: 100/100 - You have complete control over your data, with offline operation, biometric or PIN protection, and the ability to export or import your codes at any time.

Positive Security Features

• All 2FA secrets are encrypted using your device's built-in hardware security and stored only on your device
• Network traffic to Proton's servers is protected with multiple layers of independent connection verification
• Automatic cloud backup is disabled, keeping your 2FA secrets from being accessible via Google's backup services
• No advertising, behavioral tracking, or analytics SDKs of any kind are included in the app
• Crash reporting is opt-out and goes exclusively to Proton's own servers, not external analytics companies
• Your Proton account password is processed entirely on your device and never transmitted to any server
• The app requests only the minimum permissions needed: camera for QR scanning and network access for optional sync
• Google services are used only for hardware security key support, with no tracking components
• The cryptographic engine is verified for integrity on each launch, guarding against library tampering

Areas for Improvement

GDPR / CCPA Compliance

The app's privacy practices could be strengthened by:

1. Crash reporting transparency
   Surfacing the diagnostic data opt-out toggle more prominently in settings would make it easier for privacy-conscious users to review and manage what is sent to Proton's servers.

Security Enhancements

1. Single sign-on input validation
   When logging in with single sign-on, the app currently accepts login inputs from other apps on your device without verifying their origin. Adding stricter origin verification would reduce the risk of a malicious co-installed app interfering with the login process.

2. Screen protection for displayed verification codes
   On devices running Android 12 or earlier, or when biometric lock is turned off, displayed 2FA codes could potentially be captured by apps with screen recording access. Enabling full screen protection by default would close this gap.

Technical Context

App Type: Two-factor authentication, sensitive account security
Classes Analyzed: 19,607
Third-Party Services: 13
Context Tags: sensitive_data, authentication, 2fa, privacy

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About This Analysis

This security analysis was conducted by CITT (Can I Trust That), an independent security analysis service. We perform static code analysis on Android applications to help users make informed decisions about app security and privacy.

App Details

Developer: Proton AG
Version: 1.3.7 (Build 10307329)
Analysis Date: June 26, 2026
Package: proton.android.authenticator

Analysis Limitations

• Static analysis only (code review without running the app)
• Based on APK version 1.3.7 analyzed on June 26, 2026
• May not reflect server-side security controls
• Cannot detect all runtime behaviors