Does mongodb support non readable files?
BSON has a Binary data type in which you can store anything you want. MongoDB sees it as a binary blob and does not care what type of data it is, so of course ot is possible to store PDF files. MongoDB documents are limited to 16 MB in size, so if you need to store large data, try GridFS.

http://blog.mongodb.org/post/183689081/storing-large-objects-and-files-in-mongodb