ExpressKeys vs Proton Pass Comparison

• Pass Plus (individual, annual): $35.88/year
• Pass Family (up to 6 users, annual): $59.88/year

White-box design and cryptographic-trust-assumption review plus dynamic penetration testing and source-code audit of the ExpressKeys Android and iOS apps and their shared Rust core. Five senior testers, sixteen days. Backend components and third-party dependency analysis were out of scope.

Source-code review and gray-box testing of the browser extensions, mobile and desktop apps, and CLI

The vault is protected by a symmetric document key, itself wrapped by a root key derived from your vault password via PBKDF2-HMAC-SHA512 at 210,000 iterations. Cure53's March 2026 audit flagged this as GPU-crackable and recommended a memory-hard function (Argon2id or scrypt) instead.

Vault and item data are encrypted with 256-bit AES-GCM under 32-byte random keys; the user key is protected by a bcrypt hash of the account password. Authentication uses a hardened SRP implementation; sharing uses OpenPGP with ECC (Curve25519). Every field is encrypted client-side — usernames, URLs and notes included — so Proton cannot see which services you hold accounts with. Offline access on paid plans uses Argon2 for the local hash.

ExpressVPN (and ExpressKeys as one of its products) is registered in the British Virgin Islands and has been part of Kape Technologies plc (LSE-listed, ultimate beneficial owner Teddy Sagi) since September 2021.

Proton AG, Geneva, Switzerland. Since June 2024 the primary shareholder is the non-profit Proton Foundation, which the founders endowed with Proton shares in an arrangement they describe as irrevocable. Proton began as a 2014 crowdfunding campaign.