Secrecy levels: Encrypted and Top secret

In Tacq all messages are protected by end-to-end encryption. There are two secrecy levels:

• Encrypted — the default level. End-to-end encryption.
• Top secret — a level you choose yourself. End-to-end encryption, and on top of that the message goes to the recipient directly, without the server (peer-to-peer technology).

Where to switch. To the left of the input field there is an icon: a lock for Encrypted, a shield for Top secret. Tap it to choose the level; each comes with a short explanation.

The level applies to the messages you send from now on: messages already sent do not change. That is why the icon sits next to the input field rather than in the header.

Encrypted

The message is encrypted on your device separately for each of your contact’s devices, and only those devices hold the keys. The server passes the message on without being able to read it and deletes it as soon as your contact has received it; if your contact never receives it, the message is deleted automatically after 30 days. Photos, videos and files travel through the server in the same way — only in encrypted form — and are deleted together with the message. The conversation is kept on your devices, not on the server, and goes into your conversation archive once you make one.

This is how all messages arrive: with attachments, replies, edits and reactions — on all of your contact’s devices.

Top secret

The most private mode. On top of encryption, the content never passes through the server at all: it waits on your device and goes straight to your contact when you are both online. The server only knows that there is a message for your contact, not what it says.

It reaches one device. If your contact has several — say, a phone and a browser on a computer — the message goes to whichever comes online first. It will not be on the others, and there is no way to tell in advance which device it will be. That is how this mode works: on your contact’s side the message exists as a single copy and is not copied through the server or to their other devices. This is the price of the very promise the mode exists for.

Such a message can only be read, copied and deleted on your side: you cannot reply to it with a quote, forward it or edit it — otherwise its text would leave as an ordinary message.

What to keep in mind

• To deliver messages and notifications, the server works only with anonymous identifiers of the sender and the recipient and with the time of the message — at any level. Who is behind those identifiers, the server does not know: Tacq does not collect real names, phone numbers or email addresses.
• Top secret is available only in one-to-one conversations, not in groups.
• Top secret messages stay in the conversation on this device together with the others and go into your conversation archive. Until you make an archive, losing the device means losing these messages too.
• In Top secret mode, delivery may wait until you and your contact are online at the same time.

How to turn it on

Open a one-to-one conversation and tap the icon to the left of the input field: Encrypted or Top secret. The first time you turn on Top secret, a short explanation appears. The level applies to the next messages you send; you can switch back to Encrypted at any time.