How To + Security & Privacy

Use AirDrop to Securely Transfer Files Across Your Devices

Posted on May 17th, 2018 by

Use AirDrop to Securely Transfer Files Across your Devices

There are many ways to transfer files from one Mac to another, and a few ways to transfer files to and from iOS devices. The easiest and most practical way to do this is to use AirDrop, a feature built into iOS, since version 7, and macOS, since Lion (Mac OS X 10.7). Macs and iOS devices built since 2012 support AirDrop.

In this article, I'm going to show you how to use AirDrop to quickly and securely transfer files across your devices. I'll also teach you how to configure AirDrop so you don't get potentially malicious files from people you don't know.

How AirDrop Works

AirDrop uses an interesting combination of technologies to transfer files securely. It uses Bluetooth to find devices that you can send to, and the device you send from creates a secure peer-to-peer Wi-Fi network connection with the receiving device and transfers the file(s). This transfer does not use the Internet, nor a local Wi-Fi network; you don't need to be on a Wi-Fi network to use AirDrop. This makes it practical anywhere, such as in the field, where you may want to transfer files from, say, an iPhone to a MacBook Pro.

There is no limit to file size, and files transfer as fast as their individual hardware allows. Since you're not transferring files over a network, you don't share bandwidth with anyone. As a test, I transferred a one-gigabyte file from my iMac to my MacBook Pro over AirDrop in about 50 seconds. This will be slower if the devices are further apart (they were both on my desk), and if there's interference with other devices around. Also, AirDrop only works with devices that are within about 10 meters, or 30 feet, because it uses Bluetooth to create a connection (that's the distance limit for Bluetooth connectivity), then creates the peer-to-peer Wi-Fi network.

How to Use AirDrop

AirDrop is the simplest way to transfer files from one device to another. To use AirDrop, both devices need to have Bluetooth and Wi-Fi on, and neither device should be acting as a personal hotspot.

On the Mac, there are two ways to use AirDrop. The first is to go to AirDrop in the Finder by choosing Go > AirDrop, or pressing Command-Shift-R. A window shows which devices are available to received files. (All devices need to be awake to display: Macs can't be asleep, and iOS devices need to have their screen on.)

How to Use AirDrop

Drag a file onto one of the icons. The other device will receive a notification. On a Mac, it looks like this:

AirDrop notification on Mac

On an iOS device, the notification looks like this:

AirDrop notification on iOS

If you send a photo via AirDrop to a Mac, the receiver will have two options as to how to save it. If they click Accept, they can choose to save it to the Photos app or to the Downloads folder. On an iOS device, photos will be saved to the Photos app, and, for other file types, the receiver will see a list of apps to open the file, depending on the file type.

Another way to send files via AirDrop is to use the Sharing menu. On iOS, tap the Share button, then you'll see the AirDrop section populate with any devices in range that can accept files. On the Mac, right-click a file, then choose Share > AirDrop to bring up a dialog asking you which device you want to send a file.

And you can send more than just files. You can send web pages from a browser, tweets from a Twitter client, a song from the Music app on iOS, and more. Wherever you see the share button—the small square with the upward-pointing arrow—you can share something via AirDrop.

How to Keep AirDrop Secure

As mentioned above, when sharing a file, you'll see any device within range that can accept files in AirDrop dialogs. These may be your devices—say you want to send a file from your iPhone to your Mac—and it could also be devices owned by your friends, colleagues, or even strangers. Because of this, it's important to set up AirDrop so it's secure.

To do this on the Mac, invoke AirDrop (in the Finder, Go > AirDrop), then, at the bottom of the Finder window, you'll see "Allow me to be discovered by." There are three options: No One (which turns off AirDrop access), Contacts Only (which displays your AirDrop devices only to people in your contacts and uses the Apple IDs in Contacts), and Everyone (which means, well, anyone within range).

How to Keep AirDrop Secure

On iOS, go to Settings > General > AirDrop to make this change.

You should most certainly not set this to Everyone. If you do, you'll run the risk of receiving unsolicited files. These may be explicit photos that people send you, or could even be malicious files.

You may want to temporarily change this setting to Everyone if, for example, you're in a meeting and someone who is not in your contacts wants to send you a file, but remember to change it back later.

It's worth noting that, on a Mac, AirDrop is inherently more secure than file sharing, which could allow attackers to get into your Mac. If you travel a lot, it's a good idea to turn off file sharing on your laptop, because anyone on a public Wi-Fi network could access your Mac, whereas with AirDrop, the limit of 10m/30ft makes access more difficult.

When Apple first introduced AirDrop—together with features that use similar technology, such as Handoff and Continuity—the feature was buggy and unreliable. It is now rock-solid for me, and it's the way I transfer most files from one of my Macs to another, and to and from my iPhone and iPad. It's fast, it's not finicky—no more need to mount network volumes—and it's reliable, as long as you keep it secure.

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About Kirk McElhearn

Kirk McElhearn writes about Macs, iPods, iTunes, books, music and more on his blog Kirkville. He is co-host of The Committed: A Weekly Tech Podcast, and a regular contributor to The Mac Security Blog, TidBITS, and several other websites and publications. Kirk has written more than twenty books, including Take Control books about iTunes, LaunchBar, and Scrivener. Follow him on Twitter at @mcelhearn. View all posts by Kirk McElhearn →

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