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I want to split a file into M parts, such that I can recover the file from N of those M parts. (Where M>N, and I get to choose both M and N).

For example:

  1. I have FILE.IMG
  2. I split FILE.IMG into M=3 parts.
  3. I set the split-time encoding to allow me to recover the file from any N=2 of those parts.
  4. The encoding/splitting is finished, I now have FILE.IMG.1, FILE.IMG.2 and FILE.IMG.3
  5. I delete any one of those three new files, and yet I can still recover the original FILE.IMG

I use Ubuntu Linux, and hope for an answer using apt-get-able tools thereon.

Rick Ramstetter
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    This site is about helping other people with their computer problems, not about doing other people's assignments and tasks. If you need help, at least show us what you've done so far and what doesn't work. – Julie Pelletier Aug 18 '16 at 23:57
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    Might want to start with [par2](https://en.wikipedia.org/wiki/Parchive) – Mark Plotnick Aug 19 '16 at 00:32
  • For M-N=1or2, look at RAID5 and RAID6. You could use mdadm on loop devices to work with files instead of disks. – Stéphane Chazelas Aug 19 '16 at 06:57
  • I discovered and am now using the [gfshare](http://www.digital-scurf.org/software/libgfshare) (`apt-get install libgfshare-bin`) implementation of [Shamir's Secret Sharing](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing), though [par2](https://github.com/Parchive/par2cmdline) would likely also work. – Rick Ramstetter Aug 20 '16 at 01:20

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