I would like to find an HMAC-SHA256 key for a PDF file, I have been studying hashcat but it seems just to allow 51Bytes strings. My PDF file is bigger than that. How can I deal with a PDF file to find its secret key? Is it possible or I´m losing some information about HMAC procedures?

This is what I understand from the procedure:
PDF File --> Calculate HMAC-SHA256 (key unknown) 
So what I have to do is

Apply hmac-sha256 to my PDF file and a known hmac-sha256 value and bruteforce until I find the right key.
I thought that hashcat could help with that, any help is welcome!

Thanks for the help, 
 Best Regards,

Messages In This Thread
HMAC-SHA256 PDF File - by scourge - 07-27-2021, 11:43 PM