I did a backup of the library on my edge, copied the .esi file to another computer (a vm of opensuse running on XP so I can see the file in both places.)
Linux identified the.esi file as a zip file, so I copied it to another file ending in the .zip extension and then Windows identified it as a zip, file too.
The usual tools on Windows and linux read the zip file fine, there's no password, or apparent encryption in the file .zip file itself.
The .esi/.zip contains two backed-up, absolute paths, /fridge and /sdcard.
Here's a list of all the directories containing one or more files in the .esi/zip:
/fridge/.edge/.esi-data/.databases/
/fridge/.edge/.esi-data/.edb/
/fridge/.edge/.esi-system/
/fridge/.edge/.esi-system/.fontconfig/
/sdcard/.edge/.esi-content/
/sdcard/.edge/.esi-content/.esa/
I can't say what prevents the files from being read on another edge if the files are unpacked in their appropriate places.
Using Windows and Linux to navigate to the location of a commercial book I bought, Adobe Reader in both cases reports, "This document requires (DRM) features supported by Adobe Digital Editions... ... blah blah". So, Acroread reads the file and recognizes the DRM. I'd figure the file should be readable on another system with the proper user/password from original purchase.
Journal files are named jrnl_*.esj in /sdcard/.edge/.esi-content directory. Linux says they are just .gzip compressed. The variable part of the filename appears to be a hash value or date/time expressed as a hex string. Using gzip to uncompress a file shows me plain text:
Code:
<?xml version="1.0" standalone="no"?>
<xournal version="0.4.2.1">
<title>ESI journal v1.0</title>
<author>Kenneth Jennings</author>
<page width="396.00" height="540.00" tabname="">
<background type="solid" color="white" style="lined" />
<layer>
<stroke tool="pen" color="black" width="1.41">
79.68 12.00 80.16 10.56 81.60 9.60 83.04 9.12 84.48 9.60 84.48 11.04 84.48 12.48 84.00 13.92 83.52 15.84 82.56 17.76 82.08 19.20 80.64 20.16 79.68 18.72 81.12 17.28 82.56 16.80 84.00 17.28 85.44 18.24 85.92 19.68
</stroke>
blah blah blah...etc