Secret Six Translator

I have recently read a nonfiction book, George Washington's Secret Six,
by Brian Kilmeade and Don Yaeger. In it I learned this spy ring used
coded messages and invisible ink and passed them hidden in books. Each
agent was assigned a number, key places were assigned a number etc.

Here's an example:



I haven't written up a well thought out Programming Challenge for
September yet but it would go something like this

Write a program in C that reads a "dictionary" file that has number,
definition entries, and a coded message text file like the above, and
translates it to a text file like the below.



Feedback is welcome.