Make Any Public USB Port Charge-Only on iPhone and Android

Set your iPhone or Android so public USB ports only charge it, and use a data blocker to cut the data wires completely.

This guide sets your phone so a public USB port can give it power but not talk to it, and shows you the cheap plug-in blocker that does the same job in hardware. It takes about 10 minutes.

Why bother

A USB port carries data as well as power. A rigged charging port could, in theory, try to copy your photos and contacts or push malware onto your phone, which is why the FBI, the FCC and the TSA have warned travellers about airport and hotel USB ports. The honest picture: the FCC says it is not aware of any confirmed cases of "juice jacking" happening for real. But researchers showed in 2025 that a malicious charger could fake your "Allow" tap on phones from eight vendors, and those makers have been rolling out fixes since. A few settings and an inexpensive adapter make the risk very small, so it is worth doing once.

Before you start

Time: about 10 minutes.
You need: your phone and its passcode. Optional: a USB data blocker (a small adapter that passes power but not data) or a charge-only cable from a trusted supplier.
Checked on: iOS and iPadOS 26, Android 14 to 16 on Google Pixel, and Samsung One UI 8. If you are on a newer version, the settings should be in similar places; use the search bar at the top of Settings if a menu has moved.
Backup: nothing here deletes your data. Step 2 can reset app location and privacy permissions on iPhone, so you may need to allow them again.

Steps

1 Update your phone

Updates carry the phone makers' fixes for the 2025 "ChoiceJacking" attacks, where a charger pretends to be a keyboard and taps "Allow" for you.

iPhone: go to Settings > General > Software Update and install anything offered.
Android: go to Settings > System > Software updates on Pixel, or Settings > Software update > Download and install on Samsung. The name differs a little between makers.

You should see "Your software is up to date" or similar.

2 On iPhone, make wired accessories ask first

Open Settings > Privacy & Security.
Scroll down to the Security section and tap Wired Accessories.
Choose Ask for New Accessories (asks the first time each new accessory connects) or Always Ask (asks every time).

You should see a tick next to your choice. Your iPhone still charges normally from any port; only the data connection waits for your answer.

If you don't see Wired Accessories (iOS 18 or earlier), go to Settings > Face ID & Passcode (or Touch ID & Passcode), scroll to Allow Access When Locked and make sure Accessories (or USB Accessories) is turned off.

If you have ever tapped Trust on a computer or charger you don't recognise, you can clear every trusted computer at Settings > General > Transfer or Reset iPhone > Reset > Reset Location & Privacy. This also resets location and privacy permissions for your apps.