Is there a cross platform solution similar to a volume like with some DMG application installers when double clicked, they open with a prompt which pops up and asks if you agree with the terms or license before allowing you to open or access the contents of the volume.

I would like to be able to do something similar with personal sensitive files I intend to share, I want to require that recipients agree to conditions before being able to view/ access the files. As I understand it DMG only works on macs though (with no additional specialized software installed).

Readmes are usually ignored by most people, if they didn't read it, they don't have to accept the agreement. That's why I'm looking for a more in-your-face solution for confidential files, say, I was an attorney or lawyer (I am not), I would not want a terms of use to be contested just because it was easy to miss. I want to be able to be able to use a compressible archive. Encryption is desirable, but not always with a pass code. I would like an option of merely accepting the agreement as the trigger / key to decrypt the volume or archive.

Lastly, I do want this to be portable, I send stuff through email attachments, wetransfer.com, dropbox etc.

  • What would be the way you are sharing these files (over a personal or enterprise network or through google drive)? You could just create a readme.txt that is included with files. The readme could say "by viewing or reading these files, you agree to the[...]". Is how most open source software would do it.
    – bret7600
    Nov 11, 2016 at 0:33
  • Or perhaps Bitlocker might be a good choice if you are looking for encryption. hsc.fr/ressources/outils/dislocker/download
    – bret7600
    Nov 11, 2016 at 0:35
  • But Bitlocker is unavailble for macOS...
    – bret7600
    Nov 11, 2016 at 0:39
  • Possibly USB encrypted with gnupg.org/download/supported_systems.html
    – bret7600
    Nov 11, 2016 at 0:41
  • You know what, it just occurred to me that you could make any kind of unencrypted archive that has a plain text file and then a encrypted archive next to it. The Readme would have the license agreement etc, and at the bottom there would be a simple statement "if you disagree with this, close this archive and securely delete said archive immediately" and "if you agree, use _ passcode to unlock _ archive. Probably the simplest solution I can think of of the top of my head. It'd be cool if there was something fancier though. If there is, I'd love to hear about it. I'll submit as an answer tmw.
    – adamlogan
    Nov 11, 2016 at 1:30

1 Answer 1


Create a password secured zip archive of your sensitive contents.

Create a terms of use simpletext file or optionally a pdf version with the same text as these will be easily readable on just about any system.

An overly simple example:

"if you disagree with these terms of use, close this zip/image archive and securely delete zip/image archive immediately"


"if you agree, use _ passcode to unlock _ zip/image archive"

Create and place the password protected zip file and the terms of use plain text and/or pdf documents into an unsecured zip file.

The user that opens the content would not be able to miss the terms of use before opening the sensitive content.

If you're scratching your head. we are leveraging nesting as a technique to ensure users have read and accepted the terms of use before accessing the contents. Here's a picture of and a link to the Wikipedia article on Matryoshka Dolls to better visualize how this works.

Matryoshka doll with outermost top half removed. 2nd outermost doll is visible

  • The downside of this method is that it would probably only be feasible for true desktop operating systems. Opening an imagine within an image… there are plenty of people who would not know what they're doing when this happens, and they'd likely just leave the image open, anyone else that uses the computer would find an unlocked image and not have to read the terms of use to access the private data. This is an issue with most other secure image/volume based solutions. I wonder if a URI scheme or small flash or java program could be used to open the secure sensitive content image.
    – adamlogan
    May 23, 2017 at 11:17
  • 1
    Isn't it easier and more compatible to use a Matryoshka zip: nested zips with a read-me and the inner zip with your data password-protected/encrypted?
    – klanomath
    May 23, 2017 at 11:42
  • I did a search for Matryoshka zip, couldn't find anything on the topic. I got results for a phone card. Mind including a link?
    – adamlogan
    May 23, 2017 at 11:46
  • "Matryoshka zip" is just a trope/(neologism) ;-): it's simply a normal zip with another protected zip inside and an unprotected read-me (with the passphrase and an some "agreement") file.
    – klanomath
    May 23, 2017 at 11:51
  • 1
    One of the downsides of using a dmg file: Linux and Windows users have to download additional apps (dmg2img/ 7-Zip/DMG Extractor) and I'm not sure whether protected dmg files can be opened.
    – klanomath
    May 23, 2017 at 11:59

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