Security
What is encrypted, and what is not.
This page says the uncomfortable parts first. A security page that only lists what is protected is an advertisement, and you cannot check an advertisement.
That is the same sentence the app itself shows you in Settings. It is here for the same reason it is there: an app that resembles a private messenger makes a promise by resemblance, and the only way to not make it is out loud.
When you turn it on
Open any conversation, choose Turn on encryption, and from that moment the messages in it are sealed on your device and unsealed on the devices of the people in it. We store something we cannot read.
- It works in groups, not just one-to-one. This is the part most apps do not have.
- Photos, video and voice notes are encrypted too. The file is sealed on your device before it is uploaded, and the key travels inside the message.
- Your keys are made on your device and never leave it. We cannot read your encrypted messages — and we cannot recover them for you either.
- It cannot be turned off again. Deliberate: anything that could switch it off could be made to switch it off.
- Polls do not work in an encrypted conversation. They are refused rather than quietly sent in the clear.
The part everyone gets wrong
What happens when someone leaves an encrypted group
A group's encryption works by sharing a key with everybody in it. So the obvious question is the right one: what about the person who left?
They cannot read what is said afterwards
The moment someone leaves, everyone still in the group starts using a new key. The person who left holds the old one, and the old one stops opening anything.
They can still read what was said while they were there
They were in the room for it, and they have those messages on their device. Nothing can reach into somebody else's phone and remove what they already read — any app that implies otherwise is describing a button, not a guarantee.
Someone who joins reads from the moment they arrive
Never from before. A new member is handed the key as it stands, not as it started, so the history of the group before they joined stays closed to them.
Verifying
Safety numbers
Encryption stops somebody in the middle reading your messages. It does not, by itself, prove that the person on the other end is who you think — that requires checking, and checking requires something to compare.
Every encrypted conversation has a 60-digit safety number. Read it aloud on a phone call, or hold the two screens side by side. If they match, nobody is in between. If they do not, something is wrong and it is worth finding out what.
You are told when a number changes
A safety number changes when somebody reinstalls, or gets a new phone — and it also changes if somebody is intercepting the conversation. Those look identical from inside the app, so Rindit does not guess. It says the number changed and leaves the judgement to you, because the only person who can tell the difference is at the other end of a phone call.
Your account
If somebody takes over your phone number
A SIM swap is a phone call to a carrier by somebody who is not you. A recycled number is a line you stopped paying for, handed to a stranger months later. In both cases your number still works and it is no longer yours — and in an app where a texted passcode is the way in, that is the whole account.
Set a registration lock
A passcode only you know, required in addition to the texted one before your number can be used to sign in on a new device. Whoever holds the number still cannot get in.
Adding an email needs the lock first
You can have passcodes sent to an email address instead of your number. We ask you to set a registration lock before you can, and the reason is worth saying plainly: an account is only as strong as the weakest way into it. An inbox usually sits behind a password, and passwords get reused and breached. The lock is a second secret that a compromised inbox does not hand over — it puts back the protection that holding the SIM was quietly providing.
What encryption does not do
- It does not hide that you talked. Who you message, when, and how often is visible to us in every conversation, encrypted or not. Encryption hides what was said, never that it was said.
- It does not reach backwards. Turning it on protects what comes next, not what is already there.
- It does not survive onto a new device. Keys are made on a device and never leave it, so signing in somewhere new starts an empty history there. There is no backup, and nobody — including us — can recover it for you.
- It has not been independently audited. The cryptography is the standard scheme. In a browser it is built on the browser’s own primitives; on the iPhone it uses
@noble, an open-source implementation of the same algorithms, because iOS has no equivalent built in. The scheme is identical either way — only the thing doing the arithmetic differs. No outside party has reviewed our implementation. When one has, this paragraph will say so.
Deleting things, and meaning it
- Delete a message for everyone and the words are removed from our database, not flagged as hidden.
- Delete your account and the messages you sent go from other people's conversations too. Most apps cannot do this, because they were not built to.
- Take everything with you — one file with your account, your posts and the messages you sent. It contains your words, not other people's: theirs are not yours to carry off.