We handle session cookies for GitHub, Google, and other high-value accounts.
This document explains exactly what we protect against, what we don't, and how to report issues.

1. Saved session data at rest
Cookie snapshots are encrypted with AES-256-GCM before being written to disk via chrome.storage.local. The encryption key lives exclusively in chrome.storage.session — which Chrome clears when the browser closes. Encrypted blobs on disk are useless without the key.

2. Popup UI against XSS
All dynamic content rendered in the popup (account names, emails, avatar URLs, domain labels) is inserted via DOM API — never innerHTML. Avatar URLs are validated to reject data:, javascript:, and non-HTTPS schemes before render. A compromised page cannot inject script into the Persona popup by crafting a malicious page title, avatar, or og:image.

3. Content script data treated as untrusted
Everything returned by content.js — name, email, avatar, authuser — is treated as attacker-controlled input. It is validated and sanitized before being stored or rendered, regardless of what site it came from.

4. Minimal permission surface
Persona does not request <all_urls>. Host permissions are scoped to supported domains only. Additional domains are added explicitly via chrome.permissions.request() — with user consent, one domain at a time. This limits blast radius if the extension is ever compromised.

5. No external data transmission
No analytics. No telemetry. No error reporting to remote servers. No CDN-loaded scripts. The extension makes no outbound network requests except to the target sites you're actively switching to. This is enforced by the Content Security Policy in manifest.json.

Being honest about limitations is part of our security model.

Physical access to your machine
If someone has filesystem access to your browser profile directory, they can extract chrome.storage.local blobs. The AES-GCM encryption protects these at rest — but if the browser is open and the session key is in chrome.storage.session, a sufficiently privileged local process could read it. This is a browser-level threat, not something an extension can fully mitigate.

A compromised Chrome/Brave browser binary
If the browser itself is malicious or has been tampered with, all bets are off. We operate within the browser's security model; we cannot secure you against it.

Sites that store auth in localStorage or IndexedDB
Persona manages cookies. Some sites (notably SPAs using token-based auth stored in localStorage) do not use cookies for session state. Switching on these sites will not transfer the session. We document this per-site in the Site Intelligence Registry.

SameSite=Strict cookies
Chrome enforces SameSite=Strict at the browser level. Extensions cannot set these cookies cross-context. For affected sites (GitHub uses this for some cookies), we log which cookies failed and surface a warning. We do not silently proceed with a partial switch.

Session tokens that have already expired
Saved sessions become stale when a site invalidates them (password change, suspicious login, inactivity timeout). Persona shows health indicators for saved accounts but cannot prevent expiry. See the session health documentation.

Other malicious browser extensions
A malicious extension with storage permission can read chrome.storage.local. Our AES-GCM encryption protects the cookie blobs specifically against this — an attacker reading storage sees ciphertext, not session tokens. However, a malicious extension with cookies permission can read cookies directly from the browser cookie store regardless of what Persona does.

Every permission Persona requests is documented here. If you see a permission in manifest.json that isn't listed below, that is a bug — please report it.

Runtime-requested permissions (not in base manifest):

Algorithm: AES-256-GCM
Key generation: crypto.subtle.generateKey — non-extractable after first import, 256-bit
IV: 96-bit random, generated fresh per encryption operation via crypto.getRandomValues
Key storage: chrome.storage.session (cleared on browser close, never written to disk)
Data storage: IndexedDB within the extension origin (chrome-extension://[id]/), ciphertext only

The IV is stored alongside the ciphertext (prepended, base64-encoded). Each encryption call uses a unique IV — no IV reuse.

GCM authentication tag detects any tampering with stored ciphertext. A modified blob will fail to decrypt and the account will be marked as corrupted, not silently loaded.

What is not encrypted:
Vault metadata — account names, domain labels, email addresses, avatar URLs — is stored unencrypted in chrome.storage.local. This is intentional: this data is not sensitive enough to require encryption and keeping it unencrypted allows the popup to render account lists without requiring a key unlock step. If you consider email addresses sensitive in your threat model, do not use display names or real emails as account labels.

Do not open a public GitHub issue for security vulnerabilities.

If you discover a vulnerability — especially one involving cookie exfiltration, XSS in the popup, or bypass of the encryption layer — please report it privately.

Contact: ivintitus@proton.me, hello@ivin.site PGP key: keybase.io/persona-ext (optional but preferred for sensitive reports)

• Description of the vulnerability and affected component
• Steps to reproduce (a minimal proof of concept is ideal)
• Your assessment of severity and exploitability
• Whether you believe it is being actively exploited

We will credit you in the release notes and SECURITY.md changelog unless you prefer to remain anonymous.

We do not have a bug bounty program at this time. We do have genuine gratitude and will say so publicly.

Publishing source code is not a security guarantee. It is a precondition for trust.

We make the following commitments to back it up:

Reproducible builds. The extension zip published to the Chrome Web Store is built from the tagged source on GitHub using the same build.yml workflow, publicly visible. You can verify the hash matches.

No obfuscation. We do not minify or obfuscate extension source in a way that makes review impossible. Build output is readable.

Dependency audit. We pin dependencies and run npm audit in CI. We do not include packages that access the network, the filesystem, or any browser API beyond what Persona itself uses.

Extension ID pinning. Our published extension ID is documented here and in the README. Forks are welcome — but if you see Persona-branded extensions with a different ID on the Web Store, treat them with suspicion and report them to us.

Published extension ID: [published on first Web Store release]

This document is updated with every security-relevant change to the codebase.
Last reviewed by core team: see git blame.