Encrypted Daisy Format

Anyone know something about that weird format?
I downloaded a book from openlibrary. This was a zip with a some files and .txt:
“This DAISY book is encrypted with a key from the National Library
Service, and may be read on appropriate reading devices with the key
installed.
For more information, see
http://openlibrary.org/help/faq/accessing#what-is-daisy or
https://nlsbard.loc.gov
”
How to get that key? The main file is xml with cypher data :/
I’ve coded the link(s) for you this time – if you don’t know how to do it, please check the sticky thread in the helpdesk section.
Red Devil
Answer #1
http://www.daisy.org/daisypedia/daisy-digital-talking-book
i hope this helps