In short: I’m looking for a hardware/software solution to handle an amount of data, which should be accessible from multiple devices including iPhone and protected from unauthorised access.

In detail:

I’ve got a file repository of some 500GB with that I want to check in from once a day to several times an hour. Most of the data is confidential, so I can’t carry it around on an unprotected USB stick.

I want to access the repository from any of my devices, namely two Windows 10 PCs (home and work), a Windows 10 laptop and necessarily iPhone 11 Pro. (If no iPhone were involved, then the task would be trivial.)

The repository must be accessible regardless of the Internet connection, so cloud storage isn’t an option. The solution should probably include a physical storage device that I can keep on hand.

The data must be protected with a password I need to enter exactly once per connection to a device. E.g., so that I can connect the repository to iPhone, then enter a password and gain full access to the data without re-entering the password until disconnected.

I also don’t want a physical combination lock, fingerprint scanner, etc. on storage device; only a regular old-school password to enter on a PC or iPhone to which the device is connected.

I’ve tried an iDiskk device that can work as an external drive for iPhone, but it doesn’t support password encryption.

There might be some kind of specialty adapter that can connect a regular external SSD to my iPhone and works with a dedicated app, but I haven’t found one.

So I would appreciate your suggestions.

1 Answer 1


Since I got no response on a few dozen of discussion websites (not only here), I had to do my research, and here’s the result.

I was able to connect an encrypted USB flash drive to my iPhone and manage files on the drive. The general appearance of the solution is shown on the picture:

Connecting USB flash drive to iPhone

The effect is determined by several factors listed below.

  1. iOS version. According to Apple, external drives in Files app are supported since iOS 13.0, and support for encrypted drives was added in iOS 14.0 (see Files section in both sources). I’ve used iOS 14.6 on iPhone 11 Pro A2215 (MWC72RU/A).

  2. External storage device connectivity options. I’ve tested several USB devices, and I’ve no information about other connection types (e.g., SATA or Bluetooth).

  3. The device’s USB version. All my storage devices were USB 3.x, and I don’t know if USB 2.0 is going to work, too. I picked out the relatively old Kingston Data Traveler HyperX 3.0 (256GB) for this example.

  4. A way to physically connect the storage device to iPhone. I’ve used Lightning to USB 3 Camera Adapter, and it seems to be the only adapter that can work in my case. The name of the adapter is quite misleading because you can use it not only with a camera, but with other external devices as well.

    The adapter has two ports: USB 3.0/3.1 Gen 1 (for connecting an external device) and Lightning (for powering it, if necessary).

  5. Powering. After connecting a device, you might see the message: “This accessory requires too much power”.

    This accessory requires too much power

    That means you need to connect a power source to the Lightning port but beware of the pitfall: not every power source is going to suit. For instance, a 63W Belkin adapter (WCH003vf) that I usually use to charge the iPhone didn’t work for me. But an original 20W USB-C Power Adapter with an USB-C to Lightning Cable did the trick.

    I didn’t look more into this issue, but it’s surely not about wattage.

  6. Organization of data on the storage device. I tested devices of the GPT partition style only, and formatted them to FAT32, exFAT and APFS (case-insensitive), with exactly one partition occupying the entire device. In all cases, the devices were accessible from iPhone just fine when unencrypted. The device is showing up in the Files app (it’s named Kingston in my case). Encryption works in APFS only, and iPhone prompts for a password.

    An external storage device showing up in Files app on iPhone        iPhone prompts for a password to access an encrypted storage device

    I think case-sensitive APFS would also work, although I haven’t checked.

Formatting a storage device to APFS with encryption can be tricky if you don’t happen to have a Mac at hand, but I was able to do with macOS in a virtual machine.

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