In the end, Princess Nell had to apprentice herself to a master cipherer 
and learn everything there was to know about codes and the keys that unlocked 
them. This done, she was given her own key, as a badge of her office, and found 
a job in one of the stalls enciphering and deciphering books. As it turned out, 
the key was more than just a decoration; rolled up inside its shaft was a strip 
of parchment inscribed with a long number that could be used to decipher a 
message, if the sender wanted you to decipher it.