jerabaul29/qrdump

Add md5sum to the page header

Closed this issue · 7 comments

gtheler commented

The md5 sum or any other suitable hash function should be printed in the pages along the page number to help to re-order and re-assign printed pages to each original file in case of an unexpected shuffle and/or mix of pages from different files.

jerabaul29 commented

Good point, will add it soon.

jerabaul29 commented

(Btw @gtheler were you able to run the script on your machine? If you have any problems please let me know in separate issues).

gtheler commented

Yes, it runs but:

  1. when the script is called without arguments it complains about only being able to use base64. I think no arguments should be equal to -h.
  2. when I try to pass an abolute path as the input files, it complains about only being able to process files.
  3. when I follow the example from the README I do not get any PDF output. I imagine I am missing some dependency (is img2pdf a command?). It should check everything is there with which before running.
jerabaul29 commented

Ok, many thanks for the feedback. Opening separate issues and tagging you for the other points you mention.

jerabaul29 commented

@gtheler I added not MD5 (which I think starts to be regarded as a bit old) but sha512. I has been added:

  • on the 1st page in full
  • on each of the data page, 20 first chars
  • in the qr-code on the first page about metadata

You can see it for example there:

https://github.com/jerabaul29/qrdump/blob/master/doc/illustration_pdf_dump/illustration_2.png

If you are satisfied let me know and I will close.

gtheler commented

well, it's your project but the idea of adding this information is to help a human to identify a printed sheet of paper and to be able to know to which actual file the sheet belongs. A 512 ubit hash is too long for that, a 128-bit hash is better becaise
it fits in a single line without needing to chop it. As deprecated as it is, it still allows the user to differentiate two versions of the same file.

jerabaul29 commented

I do not think that taking the first 128 bits of sha512 is weaker than using the 128 bits of md5sum anyways, so if the user want to check, should be ok. Also this is not to resist attacks, for example dumped gpg keys are armoured. So I think I am happy with the current solution as you say :) .

Closing then, as this is added and functional, if you find any problem feel free to re open.