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I back up a lot of my files encrypted, but what I wonder is how to make sure that I will have access to this data in, let's say, ten years, when the tool that I used to encrypt the files is not available anymore. Are there some open standards? I ask this because even if the encryption algorithm is public, the way an encryption tool handles keys varies.

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  • Source code is eternal. As long as your encryption tool is open source, a bit of programming work can restore support for even the most abandoned of encryption tools. I'm sure they'll even have digital computer emulators on quantum computers that will enable it to work. Mar 21, 2016 at 2:47
  • while you are right, it doesn't sound like a practical solution to me
    – user430
    Mar 21, 2016 at 3:04

4 Answers 4

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Long Lived Programs

You can start by looking at encryption tools that are already long establish & have been around for years. Being well used and supported for so long is a good indicator that they'll still be around in another 10 or 20 years. Being open source can only help the odds of being "forked" and still continued in the future.

  • PGP & GPG have both been around since 1991 & 1999 respectively, can handle file encryption (with conventional passwords or public keys), and are excellent with backwards compatibility with old versions of files. They're available for just about any OS I can think of (Windows, Mac OS X, Linux/Unix, BSD) They're probably the tools most likely to "still be around in the future" (imo).

  • Linux's cryptsetup / dm-crypt / LUKS has been around for (give or take) 12 years and shows no signs of slowing. The LUKS homepage bills itself as:

    LUKS is the standard for Linux hard disk encryption. By providing a standard on-disk-format, it does not only facilitate compatibility among distributions, but also provides secure management of multiple user passwords. In contrast to existing solution, LUKS stores all setup necessary setup information in the partition header, enabling the user to transport or migrate his data seamlessly.

  • Truecrypt was released in 2004 & is still widely used, even though the official developers have abandoned it old versions still seem to work well, and there are several new forks of it. Linux's cryptsetup also supports TrueCrypt volumes too, see archlinux's wiki entry on TrueCrypt.

Software (OS) Emulation

Inspired by @allquixotic's comment about a software Emulator solution. Getting old source code for an abandoned program to work on a new OS may be a titanic undertaking to a general non-programmer user, but running an emulator and then running old software should be relatively easy.

Just keep the program you used to create the files, and maybe a copy of your OS if you have to use a virtual machine. Then use an emulator or VM.

There are still Apple II emulators available, and the Apple II was released in 1977 ($1,298 USD (with 4 kB of RAM) FYI). Android emulators are also available today. Odds are good that there will be an emulator for your favourite OS in the future. that's still available "in the future", like maybe one of these:

  • DosBox is ( as wikipedia says):

    DOSBox is an emulator program that emulates an IBM PC compatible computer running a DOS operating system. Many IBM PC compatible graphics and sound cards are also emulated. This means that original DOS programs (including PC games) are provided an environment in which they can run correctly, even though the modern computers have dropped support for that old environment.

  • And with Virtual Machine programs like VirtualBox readily available you can "install" just about any old OS you can think of (if you kept the install media or can find online) and run all your old programs to your heart's content.

Physical Security Only (Unencrypted data)

Another direction could be to create plain data CD/DVD/Blu-ray/[Future Giant disk format] disks(discs?), and instead of encrypting them, just keep them locked away somewhere safe. Like in an actual Safe, or in a bank's safety deposit box. This takes away the encryption security completely, also removing it's future readability question.

The ISO 9660 disk format has been around ~30 years (1986), odds are excellent that any future computer that has an optical drive will be able to read an ISO-9660 disk. The relatively newer Universal Disk Format has "only" been around 21 years (1995). Many disc authoring programs can write multiple formats too, using ISO and UDF (and other) formats for the same disc, ensuring greater odds of future readability.

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  • "also removing it's future readability question" Not really. Optical media has a lifespan of about 10 years (if they are of high quality and stored properly). Also today most new systems don't have an optical drive at all. Things to consider when thinking long term. Sep 7, 2016 at 12:03
  • @DavidBalažic Do you have a link / reference to the lifespan of cd/dvd/optical disks? Google seems to have a few different opinions. At any rate, making two backup copies is an excellent idea for important data, and a new copy every decade or so is a good idea (opportunity to use whichever current "future giant disk" format is popular). And you can still buy floppy disk drives on amazon (5.25" and 3.5"), they haven't been sold in new computers for decades either yet they still exist. DVD/Blu-Ray drives won't be going away any decade soon either.
    – Xen2050
    Sep 15, 2016 at 13:51
  • CDs Are Not Forever: The Truth About CD/DVD Longevity, “Mold” & “Rot” says written cd & dvd's could last 20-100 years. Has some tips like: Choose a high quality medium from a good brand. - If you want to maximize CD longevity, go for gold as a reflective layer. - Treat CDs & DVDs with care - Keep in dry, dark, and cool place - Store in jewel cases - Use non solvent-based felt-tip permanent markers, suitable for writing on CD or DVD labels - Choose slow writing speeds to reduce errors and increase quality.
    – Xen2050
    Sep 15, 2016 at 14:18
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Something worth considering is that any backup, or encrypted file could get corrupted at any time, and be unopenable. Software gets abandoned, OSes get EOLed, encryption becomes more and more trivial to break. As such, ensuring CIA (confidentiality, Integrity and availability) is a process.

I like @xen2050's idea of a VM. Especially with x86 architectures, and/or full emulators like qemu, you could set up a known, standard environment, maybe on a read only VM.

I'd however suggest treating a encrypted container as something with an expiry date. Use filenames with the expiry date "Secret-project-folder-2017-Jan-01-checksum" and have a day (a month? year?) where you check on these files, de-encrypt them, check if they're fine, and re-encrypt them from scratch with your program of choice.

This way, even if your program of choice is EOLed, dead, or compromised, you'd still have up to date files you know work when you need it, and have been tested at predictable intervals.

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There's an additional issue... if the data is not also in a common format, .txt etc, then you may find when you come to view the unencrypted file in 10 years time, there's no current software that can read it. [I've had it happen to me, with important archived material.]

Organisationally we came to the conclusion that very special projects need to have the actual machine they were created on also packed & stored alongside the data. This is, of course, damned expensive :-) & still no absolute guarantee, the machine will eventually break.

The alternative idea of making a VM of that machine at the time also suffers from the same potential outcome - that nothing is capable of running that VM any more.

In our particular case, we could retrospectively create a VM [Windows XP in this case] however, even with the co-operation of all the companies involved in the project's creation, we still could not get all our relevant software re-authorised. Some of it relied on remote authorisation services that simply no longer exist - on occasion, neither did the originating company.

With the eventual blessing & assistance from some of the companies involved, we actually used cracked software to regain some of them. The companies themselves could no longer authorise those particular versions. [I'm not giving any names, nor would I ordinarily condone such methods, but we did work in co-operation with the original companies to achieve this.]

This was an audio recording project we needed to get back to for remixing. We partially succeeded - to the satisfaction of the client - but we had to use modern equivalents of some of our 'historic' plugins to try to recreate the original sounds.

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Well, I would back up the encryption tool along with the encrypted backup files (of course making sure the tool itself isn't encrypted).

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Use an open source tool like 7zip and use standard zip encryption to encrypt your files. This is going to be around for a very long time (including 10 years) and available on a number of OS's.

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  • What if I change OS? What if the tool is discontinued?
    – user430
    Mar 21, 2016 at 3:03
  • @user430 Go with standard zip encryption (using software like 7zip), that's something that's going to be supported for a very long time and available on a number of different OS's in the future.
    – Tom
    Mar 21, 2016 at 3:08

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