Carl Hollywood had long suspected that, among other things, the network of 
the Drummers was a giant system for breaking codes. The cryptographic systems 
that made the media network run securely, and that made it capable of securely 
transferring money, were based on the use of immense prime numbers as magic 
keys. The keys could theoretically be broken by throwing enough computing power 
at the problem. But at any
given level of computing power, code-making was always much easier than 
code-breaking, so as long as the system kept moving to larger and larger prime 
numbers as computers got faster, the code-makers could stay far ahead of the 
code-breakers forever.