Background:

I've already reviewed Remove DRM from ePub Files? and How can I remove DRM from Kindle books? - the answers to which have already brought me partial process.

The challenge is that I have a few purchased *.pdb e-books that I purchased in years past, e.g. 2006. In particular, they were purchased from the palm eBook Store (ebooks.palm.com - now defunct, possibly part of http://www.ereader.com / Barnes & Noble?) - originally for use on a Palm Treo that has since died.

Of particular note is that I have a revision / publication of a book that is no longer published, and not available as an e-book from anywhere else that I've been able to find. (I feel fortunate to have even found the *.pdb files on backup.)

I have a copy of the electronic invoice for it - which includes the details necessary for unlocking - the "Purchaser's Name" and the "Unlock Code" - which is the digits of my credit card # that I had used to purchase it.

Given the above information, I was surprised to be able to open the book using the Windows eReader software and unlock it. Here I am able to view the complete contents and functionality of the book as I had done on the Palm Treo - including viewing of linked annotations / footnotes, etc.

Following the full spirit of Remove DRM from ePub Files?, I want to ensure that I can access this on any device of my choosing - especially now and in the future, and as new technologies arrive and disappear. Ideally, I'm just looking to accomplish the minimum necessary to allow import into calibre.

Outstanding Issue:

I've found a few solutions that have given me "90%" success - all based on various versions of some Python scripts - including versions 0.21 and 0.11 of "erdr2pml.py" (based on "ereader2html"). Unfortunately, unless I'm missing something, these programs are attempting to also "convert" - instead of just "decrypting". As such, the outputs are missing embedded images and/or footnotes. I.E., there is a linked, underlined, and super-scripted "a" after some text - but the content of the footnote no longer exists. I can validate this by inspecting the generated *.pmlz file, and nowhere does it contain the original footnotes that are still visible in the original *.pdb file.

I'm hoping to find a process that focuses on the decryption only, instead of attempting any type of a content conversion - or if a content conversion is required / involved, that it maintains all of the features and content of the original. (Again, I'm confident that if/once a version is obtained that calibre can import, I'll be able to fulfill the rest of my requirements.)