Is it safe to let someone use my Apple iPad charger?

One the basis of question as asked, there are two separate issues here...

The first part of this question presumably concerns whether or not you should (or would) loan your own Power Adapter and charging cable to somebody else - and, by extension, whether or not you might borrow these items from someone else.

The second element of the question, to which your subsequent comments relate, is the technical risk associated with USB power sources and charging cables. Understanding the risks associated with lending or borrowing - or connecting to a USB power source - will inform your attitudes and response to the first question.

USB (and in particular USB-C) is an active data connection that involves exchange of data. USB-C charging actively "negotiates" charging parameters between the USB-C power source and the connected device. The USB-C charging cable also contains electronic components and actively participates in the data exchange.

There are documented instances of USB power sources and connecting cables being modified by Threat Actors (i.e. the "bad guys") with the express intention of compromising either the connected device or the data stored thereon. While you might be specifically targeted - where your Power Adapter or charging cables might be surreptitiously exchanged - you are perhaps most likely to encounter this type of technical attack when attempting to charge your devices in a public environment where a USB power source and/or cable might be available as a convenience (such as Airports and other public transport hubs, shopping malls and restaurants). Professional Security Practitioners recommend that you actively avoid using public charging sources - and instead only use a trusted Power Adapter or portable Power Bank to charge your devices when away from home.

Armed with this knowledge, you will hopefully now understand that you should only charge your iPad (or other computers) using a Power Adapter or other USB power-source and cable that you trust. Purchasing a genuine Power Adapter and charging cable from a major "trustworthy" retailer (such as an official Apple Store) should ensure that you are not exposed to the risks outlined above. It follows, therefore, that you might be cautious about whom you lend your own charging equipment in the same manner that you would be cautious in lending the iPad (or other computer) to somebody else.

Setting aside the technical risks to the security of your iPad and data, also consider the potential risk of connecting to an untrusted power source or cable - as, if they have fault, they have the potential to cause significant or irreparable damage to the connected device.

Hopefully you are now better equipped and informed - and can make an objective analysis as to the risks associated with lending or borrowing a USB Power Adapter and/or USB charging cable.

As long as they’re only using it to charge a normal, factory-made, USB-powered device.

Thanks for this VERY thoughtful addition.

I was contemplating adding something similar, but just couldn’t muster the energy necessary to provide an adequate treatment of the subject.

A power adaptor only contains digital data about itself. e.g.:

• model
• serial number
• wattage

Any “data” which might be contained in the cable’s “chips” are used by the power adaptor and the device’s power supply to negotiate the charge rate.