⚠ Not yet reviewed by a lawyer. Sourced information, to be confirmed.

Signal groups: as a member

Signal groups: overview

Terms used here: the groups (public, airlock, trusted), the roles (HR, keyholder…) and the vocabulary.

Your path

1. Get ready → activist name, hidden number, disappearing messages (see below).
2. Join the public group → read the announcements.
3. Join an airlock group announced in the public group, or suggest one to a secretary, to meet in person. If a vetted member already knows you, they can also co-opt you: they propose you directly to a secretary.
4. Come to meetings and actions → a vetted secretary helps you set up Signal and scans your account's QR code.
5. Validation → once a vetted member who knows you vouches for you to the secretary; otherwise, keep coming to actions: that is where people get to know each other.
6. Join the trusted group → an HR member joins you in the airlock group, checks your profile, has you review the full charter, then adds you to the trusted group by your username: no link to ask for or follow.
7. Take part → nothing illegal in writing; doubts about someone: HR, privately.
8. Arrested, lost your phone, group gone → see below.

Your activist name

The same name on Signal and in person, at meetings and at protests: you don't shout a real first name in a march, and two different names always end up getting mixed up.

• Short and easy to say: two syllables, a common first name or a simple word ("Lou", "Max", "Linden"). It must be easy to shout, remember and spell.
• Unconnected to you: not your initials, not a nickname your family or colleagues know, not a handle you already use elsewhere (social media, games, forums).
• Unique in the group: check it isn't already taken.
• If a full name is needed (sign-up, car-share list), an equally simple fake surname; never your real name in a group.
• Don't ask for other people's real names, and don't give yours, even in confidence: what you don't know, you can't say in police custody.

Your settings

Do this before joining your first group, airlock group included: once you are in, your old profile has already been seen. A secretary helps you at the meeting; nobody else takes your unlocked phone in hand.

In Signal

• Profile name: your activist name; no photo of yourself (or a neutral image).¹
• Number hidden from everyone: Settings › Privacy › Phone number › "Who can see my number": Nobody (the default, but your number stays visible to anyone who already has it in their contacts), and "Who can find me by my number": Nobody (by default, anyone can check that your number is on Signal).² Signal itself knows your number; in response to a legal request, it says it can only provide the registration date and the last connection.³
• A username (it ends with at least two digits) so people can add you without your number.¹
• Disappearing messages by default for all new chats: Settings › Privacy › Default timer for new chats.⁴
• Signal PIN and registration lock: the PIN protects your account; with registration lock on, nobody can re-register your number on another phone without it.⁵
• Signal's lock (Settings › Privacy › Screen lock): the app locks after a period of inactivity. It has no code of its own: it uses the phone's (or fingerprint, face).⁵
• Hide screen in app switcher and link previews off ("Generate link previews" setting).⁵
• Notifications with no name or message: Settings › Notifications › Show, then the option that shows neither the name nor the message (Android: "No name or message"; iPhone: "No Name or Content"). By default the sender's name and the text appear on the locked screen, so a group name or a sensitive message would be readable by anyone holding the phone. The exact labels vary with the system and the language.⁶
• No real names in your address book: if a comrade's number is saved there, Signal shows you the address-book name, not their activist name.⁷ On a seized phone, that links the two. Connect by username rather than number, remove comrades from your contacts, or revoke Signal's access to contacts (phone settings › Signal › Contacts). If you want a reminder, use Signal's nicknames, visible only to you,² with the activist name, never the real one.
• No backup of group history to the cloud or a shared computer; no automatic saving of photos to your gallery.

On the phone

• A code of at least 6 digits or alphanumeric: it is what protects your messages, since Signal uses it. Biometrics off before an action, quick auto-lock (phone: lock, passcode and seizure).

In the groups

• Nothing illegal in writing: no calls for violence or damage, no threats, not even as a joke (see the box above). Sensitive matters are discussed in person, without phones.
• No voice messages: your voice identifies you, it is biometric data,⁸ and a voice note also picks up the sounds around you (place, other voices). It is also played out loud, sometimes near other people. Write instead.
• Clean links before sharing them: a link copied from Instagram, TikTok, YouTube or X often contains a share ID tied to your account (?igsh=, ?si=, short vm.tiktok.com links…). Public tools can find out who shared it.⁹ Delete everything after the ?; for a short link, open it first, then copy the full address and clean it.
• Blur faces before sending a photo, with Signal's blur tool.¹⁰ No real names, addresses or screenshots.
• No live location: a meeting place is given in person, or at the last minute in the airlock group.
• Need help? Name someone: "@Lou, can you handle the banner on Saturday?" rather than "can anyone…?". The bigger a group, the less each person responds, except when you name the person.¹¹¹² Emergency: call 15 or 112, not the group.
• Label: Signal lets you show your protest role (medic, legal…) next to your name, in each group separately; only set one if the charter says so, and never an organising role (see role labels).
• Doubts about someone: HR, privately. Never accuse anyone in the group: a rumour of a leak destroys a group more surely than a real leak. An HR member or a keyholder can remove someone as a precaution while two HR members decide (preventive pause).
• Never share the link or QR code of an airlock group, a trusted group or a sub-group (only the public group's link is shared): give your username to the person who must add you, and add others the same way. If you spot a link somewhere, tell the keyholders, who turn it off straight away.¹³

If you are arrested or lose your phone

1. In police custody, talk about no one: you have the right to remain silent,¹⁴ and nothing obliges you to talk about others, your groups or their members (police custody).
2. Tell HR as soon as possible, in person or through a comrade: you will be removed from the groups as a precaution, nothing personal.
3. Recover your account on another phone with your number and PIN, then remove any unknown linked devices (phone: if your phone is seized or lost).
4. At the debrief, say everything: phone taken, unlocked, code given, how long out of your sight. It isn't a failure; it is what protects the others.

If the group disappears or you are removed

• Plan ahead: remember, without writing it down, the activist name of your secretary or of an HR member, and a fallback point agreed in person (a regular place and time: market, assembly, roundabout).
• Don't panic: a removal is often a precaution (you were near an arrest, a phone was lost).
• Don't leave a group on your own because it seems compromised: wait for keyholders or HR to tell you. As long as you are in it, you are on the list of people to re-invite.
• Don't create a replacement group and don't talk about it on another network; go to the fallback point or contact HR.
• Only accept an invitation from a keyholder or secretary you know, to a group that follows the naming scheme; if in doubt, check in person. An invitation from a stranger, or one posted in the old group, may be a trap.

Leaving properly

1. Leave the group: group settings › Leave group.
2. Delete the chat: deleting the chat does not leave the group, and leaving does not delete the history.¹⁵
3. Delete what remains elsewhere: saved photos and files, screenshots, and the chat on your linked devices (Signal Desktop).
4. Tell HR so the register can be updated.

Previous : Overview · Next : Recruiting and meeting

In one of these situations? keen to get involved or trained · new to the Signal organising groups

Sources

Each note links to the source of the information. Most sources are in French. Laws change: check the date of the source and, if in doubt, ask a lawyer.

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1. Signal — Keep your phone number private with Signal usernames · AI-sourced on Oct 29, 2026 · awaiting human check ↩↩

2. Signal — Phone number privacy and usernames deeper dive · AI-sourced on Oct 29, 2026 · awaiting human check ↩↩

3. Signal — Government communication (legal requests received and data provided) · AI-sourced on Oct 30, 2026 · awaiting human check ↩

4. Signal — Set and manage disappearing messages · AI-sourced on Oct 29, 2026 · awaiting human check ↩

5. EFF Surveillance Self-Defense — How to use Signal · AI-sourced on Oct 28, 2026 · awaiting human check ↩↩↩

6. Signal — In-app notification options · AI-sourced on Oct 31, 2026 · awaiting human check ↩

7. Signal — Signal profiles and message requests · AI-sourced on Oct 29, 2026 · awaiting human check ↩

8. CNIL — "À votre écoute": white paper on voice assistants (in French) · AI-sourced on Oct 29, 2026 · awaiting human check ↩

9. BehindIt — revealing who shared an Instagram or TikTok link (GitHub) · AI-sourced on Oct 29, 2026 · awaiting human check ↩

10. Signal — Blur tools · AI-sourced on Oct 28, 2026 · awaiting human check ↩

11. Markey (2000) — Bystander intervention in computer-mediated communication, Computers in Human Behavior · AI-sourced on Oct 29, 2026 · awaiting human check ↩

12. Darley & Latané (1968) — Bystander intervention in emergencies: diffusion of responsibility · AI-sourced on Oct 29, 2026 · awaiting human check ↩

13. Signal — Group link or QR code · AI-sourced on Oct 29, 2026 · awaiting human check ↩

14. Service-Public — Garde à vue · AI-sourced on Oct 28, 2026 · awaiting human check ↩

15. Signal — Delete messages, alerts or chats · AI-sourced on Oct 29, 2026 · awaiting human check ↩