Audience

Your Phone in Someone Else’s Hand

An Airport Queue, a Stranger’s Thumb and a Nephew in the Window Seat

Some apps can ask for a fingerprint before they open, even on a phone that is already unlocked.1 This is one of those mornings, in Noor’s airport terminal.

  • WhatsApp’s App lock asks for a fingerprint before the app opens, and can lock again straight away, after a minute or after half an hour.1
  • Signal’s Screen lock uses the phone’s own PIN, passphrase or fingerprint, and until it is given, Signal cannot be used.2
Noor in a bag drop queue at the airport with a suitcase, a coat over her arm, handing her phone to a man with a backpack behind her

Noor hands her phone to a stranger

The queue for bag drop is long, and Noor has a coat over one arm. A stranger behind her asks which flight this line is for, so she opens her boarding pass and hands him the phone. While he reads it, a WhatsApp message from her sister drops in at the top of the screen, his thumb lands on it, and her sister’s chat opens in front of him.

Noor lends her nephew the phone at the gate

The flight is late, and her nephew is bored. Noor gives him the phone for a puzzle game and goes to fill a water bottle. When she comes back, he has found Signal, opened the chat at the top of her list and is holding down the button for a voice message, singing to a friend of hers he has never met.

Noor’s nephew by the window on a plane, holding a phone, with Noor in the next seat reaching toward it

Noor gives her nephew a game on the plane

On the plane, her nephew has the window seat and wants the game again. Noor finds it for him and hands over the phone. By the time the drinks cart comes round, the game is gone and he is in WhatsApp, scrolling through the photos in her family group and laughing at one of his mother.

By two in the afternoon

Noor had taken handing over her phone for handing over all of it. She had no idea WhatsApp and Signal each kept a lock of their own, both under Privacy.

True to you

What your phone does is up to you. We think so too. So we built TrueTo to make every app behave the way you do. That’s what true to you means.

TrueTo goes into each app and changes the setting the way you would. Every one of them is reversible, one at a time.

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Noor hands her phone to a stranger

If Noor had used TrueTo, it would have gone into WhatsApp and Signal and turned on App lock in WhatsApp and Screen lock in Signal for her.

Noor lends her nephew the phone at the gate

With Screen lock on in Signal, the app would have asked for Noor’s fingerprint or PIN before her nephew could open it.

Noor gives her nephew a game on the plane

With App lock on in WhatsApp, the app would have asked for Noor’s fingerprint before it opened, and each lock would have stayed hers to turn off, in its own app.

App lock

In WhatsApp, under Settings and then Privacy, Noor can turn on App lock herself.1 In Signal, under Settings, then Privacy, then Screen lock, she can turn on Use screen lock.2

Sources

  1. Shah, Parth, “How to Lock WhatsApp With Face ID or Fingerprint on iPhone and Android,” Guiding Tech, August 1, 2024.
  2. Signal, “Screen Lock,” Signal Support, read October 12, 2026.