Microsoft's PDFs don't open on linux?

2 days back, I downloaded 3 ebooks from Microsoft. I downloaded it because, they were giving the whole book for free and who needs to pay exhorbitant prices for hard-bound books. Anyway, the download was from my linux distro(Mint). After the download, to my dismay, Evince showed that it was password protected. I started looking out for PDF password crackers and even tried some common words like microsoft, microsoft.com, name of the book, the filename but nothing helped. Just out of curiosity, I try to open the file from Windows and it opens!! Is this restriction something to do with MS or Evince?