cracking a pdf

Hello,
Total noob
So I have a pdf - unable to open without a password. I have zero idea of the length , characters or anything about the password. I know the pdf has 128 bit RCA4 encryption. I only have a intel core i3, and no gfx cards.

1) Is it possible to crack the password in reasonable time < 1 month? A brute force program is telling me 1 year+.

2) How do I go about this ? I have generated the hash using pdf2john.py and tried using hashcat but it just keeps telling me hash was not read.

Thanks