End-to-end encryption, explained simply
Without the jargon: what end-to-end encryption means, how to spot the real thing, and where its limits are.
"End-to-end encrypted" is printed on almost every messenger today. Most people nod it through without knowing what it means, and miss the one difference that matters. So, step by step, without jargon.
Three ways to protect a message
Not at all. The message travels in plaintext. Every node in between can read it. Sounds absurd, but for decades that was the norm for email and SMS.
Transport encryption. The message is encrypted on its way to the server, but decrypted there, stored, and re-encrypted for forwarding. So the provider can read everything. That is the case with many chat services, including some that advertise being "encrypted".
End-to-end. The message is encrypted on your device and only decrypted on the recipient's. The server in between sees nothing but gibberish and cannot resolve it, because it does not hold the key. That is the difference.
The decisive sentence
With real end-to-end encryption the key lives only with you and the person you talk to. Not with the provider, not "kept safe" and not "for emergencies only". Simply not at all. If a provider can reset your password and then show you your old messages, it held the key, and it was not real end-to-end encryption.
How it works technically
Simplified: everyone has a key pair, a public key they may hand out and a private one they never give away. Whoever writes to you encrypts with your public key. Only your private key opens it. It is like a letterbox: anyone can post, only you can take out.
PriChat uses the same approach as Signal:
- X3DH establishes a shared secret on first contact, without both of you having to be online at the same time.
- Double Ratchet then changes the key for practically every message. Even if someone captures a single key, they can decrypt neither earlier nor later messages. That is called forward secrecy.
What encryption cannot do
Too much gets promised here, so let us be clear:
- It does not stop someone reading over your contact's shoulder. The recipient sees plaintext, always.
- It does not protect metadata, meaning who talks to whom and when. That needs extra measures (in our case: sealed senders and pseudonymous groups).
- It does not protect a compromised device. Whoever reads your screen needs no key.
- It does not protect against scanning before encryption. That is exactly why client-side scanning is so dangerous.
Ask yourself: can the provider restore my old messages if I forget my password? If the answer is yes, it holds a key. At PriChat the answer is no, which is why we give you a recovery phrase instead.