The core of ProtonMail’s security model is client-side encryption. When a user composes an email, the encryption process occurs within the user's web browser (the client) before the data is transmitted to ProtonMail’s servers. This is achieved through JavaScript libraries that execute cryptographic algorithms locally.
To address this, ProtonMail developed "Password-protected Emails." This feature encrypts the message to a symmetric key (a password chosen by the sender). The recipient receives a link to the ProtonMail web app, where they can decrypt the message using the shared password. This extends the security model to non-ProtonMail users, though it requires out-of-band communication of the password. protonmail web app
: Choose the Proton Free plan or a paid version (like Mail Plus) depending on your needs. The core of ProtonMail’s security model is client-side
A primary challenge in cryptographic software is the "usability gap." Historically, tools like PGP (Pretty Good Privacy) required complex key management, manual key exchanges, and command-line proficiency, limiting their adoption to a niche audience of technologists. : Choose the Proton Free plan or a