I guess, here is the description:

http://www.angelfire.com/b

One of the ways is to read the fisrt matrix as strings and then tokenize

into individual numbers use this method Integer.parseInt(String, 16)

and get [4][4] array of integers

Then you read matrix of decimal integers.

Then you multiply matrices and

transform each one with Integer.toHexString

and you should get another matrix.

I don't understand, though, it should be not just simple multipilication

as all numbers should be no bigger than ff after multiplication -and I'm not

sure I understood from the above metntioned text