[Jason Fagone:] The invention of radio completely transformed the value of code breaking.
So it put an incredible premium on cryptography,
on strong codes and ciphers
because now that those messages were flying through the air
they had to be protected.
The problem for America is that on the eve of World War I
the United States was completely unprepared
to break codes in the war.
The United States had no code breaking agency or bureau
in the United States military.
It just didn’t exist.
There was no NSA. There was no CIA.
The military branches had their own very, very small intelligence agencies,
we’re talking about dozens of people not thousands in this case.
[Narrator:] At Riverbank, George Fabyan saw an opportunity to serve his country –
and to enhance his reputation.
He established the first dedicated codebreaking unit in America
and, much to their disbelief,
placed Elizebeth and William in charge.
Soon, the Navy and the War, State, and Justice Departments
were sending thousands of secret messages to Riverbank for decryption.
[Houghton:] So William and Elizebeth Friedman at this point
hadn’t really done this systematically for very long.
They’d kind of played with it a little bit.
But all of a sudden, they’re being asked to break codes for the United States military in a world war.
Talk about on the job training,
this is as deep as on the job training gets.
[Narrator:] The couple scrambled to expand their knowledge of codebreaking:
starting with the most fundamental concepts
like the difference between a cipher and a code.
[Houghton:] A code is when you take a word or even a phrase
and you replace it with another word or a phrase.
So if we have the word “gun”
we might say every place the word gun is, we’re going to put “Bob” instead.
That way you’re able to replace the words,
but if somebody intercepts your message,
they may not actually know there’s a secret message there,
because it reads like plain text.
A cipher, on the other hand, is taking individual letters
(or groups of letters)
and changing them through some process,
through some algorithm,
into other letters, into numbers, into symbols, into anything,
so that you can mix up the message and make it unreadable.
[Narrator:] Using a method that had been around for hundreds of years,
they began decrypting messages using frequency analysis.
[Houghton:] This is what’s called a frequency chart.
This is what allows a code breaker to very effectively look through an enciphered message
and say okay, look, there’s a lot of Ns,
there’s a lot of Gs,
there are a lot of Qs,
so the likelihood is those are going to be some of these very common letters in the English language.
Es, Ts, Ns, As…
If we understand this in a very mathematical way,
it can help us to attack secret messages and break them down
and understand what they actually mean.
[Narrator:] Elizebeth quickly discovered that she was quite good at spotting patterns hidden in the texts.
Before long, though, William and Elizebeth reached the limits of what was known about codes and ciphers
and they began inventing their own methods.
[Fagone:] They figured out methods of solving secret messages
that had never been imagined before.
For the first eight months of World War I,
this sounds incredible but it’s completely true,
Elizebeth, William and their colleagues at Riverbank
broke all messages for every part of the US military and the Department of Justice.
[Narrator:] They documented their breakthroughs in eight volumes --
known as the Riverbank Publications,
which established a mathematical foundation to the principles of cryptology.
[David Hatch:] Prior to the publications at Riverbank from Elizebeth and William,
cryptology had been thought of as a field for linguists,
for people with knowledge about foreign cultural areas
and perhaps math might be a tool.
But the Riverbank Laboratories’ publications turned cryptology from language to statistics.