End-to-end encryption

End-to-end encryption (E2EE) is the scheme in which a message is encrypted on the sender's device and only decrypted on the recipient's device. The keys stay on the devices; the server that carries the message holds a package it cannot open itself.

How it works, with no math

Every device generates a pair of keys: a public one, given out to anyone who wants to talk to it, and a private one, which never leaves it. Whoever writes encrypts using the recipient's public key; only the matching private key reverses it. If the server is breached, the attacker gets scrambled text.

The side effect is symmetric and rarely remembered: if the server cannot read it, the server cannot recover it either. That is why WhatsApp cannot restore a lost conversation for you.

What end-to-end encryption does NOT protect

• Metadata. Who talked to whom, when, from which number and how often. None of that is content, and none of it is end-to-end encrypted.
• The endpoints. An unlocked phone, a WhatsApp Web session left open at the front desk, a screenshot. Encryption protects the path, not whoever is already inside.
• A poorly configured backup. A cloud copy with no encryption of its own falls outside E2EE's scope and depends on the cloud account's own security.
• Whoever is already one of the endpoints. If the customer writes to the business, the business is a legitimate recipient: it can read, store, export and forward.

In business support, the rule is different

A conversation between two people in the app is E2EE by default. A conversation with a business using the official API passes through a server — the business's own or a provider's — and WhatsApp itself warns, inside the chat, that the message can be read by employees and contracted vendors there. That is not a flaw: it is the model. A team of ten agents needs ten people to see the same conversation.

What replaces the technical guarantee here is process: role-based access, a log of who read what, a retention period, and a contract with the vendor. The topic leaves the field of encryption and enters that of privacy law.

In transit and at rest are different things

TLS (the browser's padlock) encrypts the path to the server, and the data is opened there. Encryption at rest encrypts the disk where it is stored, and the system holds the key. Only end-to-end prevents the intermediary from reading it — the other two block third parties, not the server's owner.