PGP True E2E Plugin

Caution

To get all features (local search, webauthn, export/import settings) you must use the version >=1.7.8 of bulwark mail.

End-to-end PGP for Bulwark Webmail, implemented as a privileged (same-origin) plugin. All cryptography runs locally in the browser — no key material ever leaves your device.

Main Features

• Core Cryptography — Seamlessly encrypt, decrypt, sign, and verify emails locally using a modern OpenPGP engine.
  • Formats supported: PGP/MIME (Read & Write) | Inline-PGP (Read-only, for legacy compatibility).
• Zero-Disk Session Security (100% RAM) — Unlike traditional plugins that temporarily write unlocked secret keys to shared browser storage (like IndexedDB), PGP True E2E isolates unlocked keys strictly within active plugin memory. Your decrypted keys never touch the disk, not even for a millisecond, ensuring instant destruction upon tab closure or browser crash.
• True End-to-End Drafts & Attachments — Standard PGP extensions only encrypt when you hit "Send", leaving your auto-saved drafts and attachments exposed to the mail server in cleartext while you write. This plugin intercepts the webmail's auto-save and upload cycles, encrypting drafts, attachments, and metadata (such as filename and MIME type) locally in the browser before they ever reach the network.
• Encrypted-at-Rest Local Search Index — PGP True E2E securely decrypts and indexes your emails into a local, encrypted-at-rest database. Search your secure history instantly without leaking a single keyword to the mail server or writing decrypted text to the disk.
• Automated Key Exchange — Automatically detects and imports public keys attached to incoming signed emails, making recipient keyring management effortless (optional).
• Keyserver Integration — Seamlessly publish your public key to or fetch recipient keys from keys.openpgp.org directly within the interface.
• WebAuthn Passwordless Unlock — Don't want to type your passphrase every time you open your webmail? Unlock your keys with a single click using WebAuthn/Passkeys (requires a hardware key/FIDO device supporting PRF).
• Public Key Attachment — One-click option to automatically attach your public key to outgoing emails.
• Import / Export — Easily backup and restore your local search/preview index and PGP keys.
• Dynamic Recipient Badges: Real-time check during drafting to see if To/Cc/Bcc addresses have valid public keys, displaying a visual badge next to them.
• Smart Encryption Fallback: If some recipients lack PGP keys, prompt the user before sending two separate emails with the same Message-ID (one encrypted to PGP-capable recipients, and one in cleartext to those without keys).
• Generate yours keys : You don't have keys ? You can generate them within the client ! Once generated, you will get a revocation certificate and a emergency code to unlock the key if you lost the passphrase. (1.0.2)
• Admin policies : Decide what you want to your users (1.0.2) : you can
  • enforce encryption : Force users to add/generate a key before they can send an email to a recipient. It ensure all users have a key.
  • enforce Drafts and attachments encryption whatever the users decided
  • block until users unlocked their default keys : that ensure users have their key unlocked. It automatically enable for user the 'Ask for default key on booting' option
  • allow persistent keys : Used to disabled the Dangerous Persistent Storage of keys. Disabling force users to type passphrase each time they connect to webmail but it is more secured.
• Onboarding for new users (1.0.2) For new users which don't have key, there is an onboarding allowing them to generate keys and understand how PGP works.

For more details, refers to DOCS.md file.

Security & Threat Model

• Privileged Tier: The plugin declares tier: "privileged" + crypto:full. Per resolvePluginTier, the same-origin tier is only granted to a signed, admin-approved (managed) bundle after high-risk consent. Self-uploaded copies are refused (not downgraded)—it must be signed and shipped through the admin channel.
• Keys at Rest: Private keys are re-wrapped with AES-256-GCM under an argon2id + generated salt (default) or PBKDF2 (SHA-256, 600,000 iterations, legacy) key derived from your custom passphrase. They are stored in IndexedDB; raw private key bytes are never persisted.
• Keys in Use: Unlocking a key stores it strictly in RAM. It is never persisted to IndexedDB or written to disk during the active session.
• XSS & Isolation Limit: The background part of the plugin acts like a service worker, communicating keys to other sandboxed components.
  • Note on Threat Model: If an attacker successfully executes arbitrary JavaScript in the client (via XSS or a malicious third-party plugin), they could potentially intercept keys in memory. This is an inherent limitation of web-based cryptography. However, our 100% RAM isolation significantly reduces the attack surface compared to disk-bound alternatives that write active keys to browser storage.
• Keys in Use: with DangerousStorage activated : Stored encrypted with a non extractible AES key. It allows user to avoid decrypting when refreshing (avialble in 1.0.2)
• Output Sanitization: Returned HTML still passes through the host mail sanitizer before rendering.

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Roadmap (Planned Features)

• Address Book Integration: Native integration of public keys within the Bulwark contact/address book. Available in next release (1.0.2)
• Server vs. E2E Badges: Display a dedicated badge in the email list row to distinguish between E2E encrypted emails and those encrypted server-side (requires a new hook and Stalwart Server modifications). If you want to get this feature, show your interest here : https://support.stalw.art/t/add-an-explicit-server-encryption-marker-header-for-at-rest-encrypted-messages/1139 because now, we can't know if the mail is E2E encrypted or just stored encrypted.
• Sync settings + keys accrois devices. Require new clients hook
• Check WKD of domains to search keys

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Build & Installation

npm install         
npm run package

Dependencies

We use

• OpenPGP, of course
• mimetext to generate the mime message when encrypting

Thanks

This plugin is inspired by the official S/MIME plugin. Heartfelt thanks to its author, Linus Rath, for his invaluable work!