Original subtitles

Tonight on "Secrets Declassified,"

cracking secret codes that win battles and save lives,

from the Pacific, where a U.S. codebreaker races

to prevent another Pearl Harbor...

This code is just about impossible to break.

To Vietnam, where U.S. airmens' escape route is plotted

with clues from an unusual source...

They're gonna use the layout

of his favorite golf courses as a code.

To a housewife in Virginia

that reveals her husband is selling

top secret codes to the enemy.

Tucked away in the closet is a grocery bag

stuffed with classified Navy documents.

These are the astonishing and sometimes terrible things

done by governments and the people who work for them.

It's time to bring them to light.

The first hole at Tucson National Golf Course

is 430 yards and bends to the left.

The fourth at Abilene Country Club is 195 yards.

They might sound like trivial facts,

but for one U.S. airman shot down behind enemy lines

in Vietnam, they're the difference

between life and death.

On Good Friday, 1972,

the North Vietnamese launch a massive

surprise assault into South Vietnam.

The U.S. Air Force scrambles to launch

a series of tactical air strikes

to try and contain this invasion.

And many airmen who've been looking forward

to some leave suddenly find themselves back on active duty.

One of the unlucky men recalled from R&R

is 53-year-old Gene Hambleton.

Gene Hambleton is a navigator and an electronics specialist

in the U.S. Air Force.

He seems old to still be flying

combat missions, but it's his expertise in jamming

enemy radar that puts him back into the cockpit

heading to North Vietnam.

Just minutes into his mission,

his airplane is struck, and he finds himself

having to parachute into enemy territory.

For the U.S. military,

Hambleton isn't just another man down.

Because of his seniority,

Hambleton has an intimate knowledge

of top secret strategic air command operations.

He cannot be allowed to fall into enemy hands.

The race is on to find Hambleton

before the enemy does.

The Air Force manages to make radio contact with Hambleton,

and they launch one air evac after another.

But the rescue choppers keep getting shot down.

Then the Navy SEALs propose

a different kind of rescue.

Their plan is to covertly sail up the Mieu Giang River

and pluck Hambleton from an extraction point

two miles away from his current location.

There's one big problem.

The survival radio that Hambleton has

allows him to communicate with American forces,

but it also allows the enemy to listen in

on those transmissions.

They're going to need a secret code,

which only Hambleton can understand.

That's a lot easier said than done.

The rescuers reach out to Hambleton's squadron

to find things out about his personal life,

so they can come up with a coded language

that he would understand and the enemy wouldn't.

They discover that Hambleton

is an avid golfer, but not only that,

he has freakishly encyclopedic knowledge

about the world's most renowned golf courses.

Maybe they can encode a route to the extraction point

using the layout

of his favorite golf courses as a code.

It's a crazy idea, but it's the only hope

the Air Force has of getting their man back.

The rescue team starts overlaying

golf course plans over aerial reconnaissance photos.

And they start plotting a route

to the extraction point

across farmland that also stays away from roads

and enemy positions,

and they break that plan down into nine stages.

Each of those stages corresponds

to the individual length and bearing of a hole

from an iconic golf course.

Forget Whistling Straits, Augusta, or the Ocean Course.

This will be the toughest round of golf anyone has ever played.

On April 10th, Hambleton's radio

crackles to life.

The voice on the other end belongs to

Air Force Captain Harold Ike.

Hambleton's life depends

on him being able to decode what he hears next.

Ike tells him,

you're going to play nine holes,

and you're going to get in the Suwannee.

The round starts at number one at Tucson National.

Now, at first, Hambleton's totally confused

as would be any of the North Vietnamese

that are listening in.

But then Hambleton realizes that message

is so strange, it must be a code.

The Suwannee is a river in the U.S.,

So he figures they must be giving him coded directions

to get to a nearby river.

Hambleton racks his brains

trying to remember everything he can

about the course at Tucson.

The first hole is 430 yards running southeast.

Suddenly, he realizes that's his first direction.

Hambleton can hear enemy activity all around,

so he waits until the cover of nightfall before teeing off.

As he starts moving, it's tough going for Hambleton.

He has to count his strides, moving through darkness,

navigating through potential minefields,

and avoiding enemy soldiers.

After 40 minutes, he makes it to the first hole.

That's one hole down. Eight more to go.

He makes it through four holes

before dawn breaks when he takes cover again.

Next evening, he moves on to hole 5,

and this one comes with a serious hazard.

The fifth hole is the number four

at Abilene Country Club, where Hambleton

once hit a hole in one.

This time it's not so easy.

The route takes him right through the outskirts

of a Vietnamese village.

As he's tiptoeing through this village,

suddenly, from around a building,

a man leaps out at him brandishing a blade.

Instinct takes over, and Hambleton

pulls out his own knife, plunging it into his attacker

before escaping onward into the jungle.

Now his next round is against the clock,

because once the body is discovered,

the North Vietnamese will be hot on his trail.

Over the final four holes,

Hambleton grows weaker and weaker.

After three days,

Hambleton makes it to the ninth and final hole.

He locates his extraction point and waits.

It feels like his ordeal is nearly over.

Then Hambleton's heart sinks.

He spots a sampan boat heading upriver

towards him, with a Vietnamese man on the prowl,

holding an AK-47.

Days of surviving in the jungle,

only to get caught now.

But then someone else emerges from the boat.

It's an American.

It's the Navy SEAL extraction team.

News of Hambleton's rescue

hits the headlines, but something crucial is missing.

All mention of the Navy's clever code

has been scrubbed from the stories.

The secret remains locked away for nearly a decade,

until 1980, when Hambleton finally reveals

the story of his amazing escape

and the world hears of one of the U.S. military's

most audacious codes.

Improvising a code to rescue a man

behind enemy lines is one thing.

But during World War II, the U.S. military

needs something that can save thousands

and help turn the tide of the war.

So they turned to an unlikely source,

an ancient Native American language.

After months of Naval warfare,

the U.S. military is prepping to engage the Japanese

on land for the first time,

and their plan is to island hop their way

across the Pacific towards the Japanese mainland.

Radio communication will play

a pivotal role in the campaign,

but it has a downside.

In the chaos of battle,

there is no quick way to encrypt

or decrypt battlefield commands.

So Japanese forces will be able to hear

everything the U.S. is saying.

In 1942, an engineer

raised in a remote region of Arizona

has an idea which could change all that.

His name is Philip Johnston.

Philip Johnston was

actually raised by missionaries on a Navajo reservation.

And as such, he learned the Navajo language.

Johnston recommends to the U.S. Army

using Navajo speakers as code talkers,

communicating battlefield orders in real time

before the Japanese can decipher them.

It's estimated that less than 30 non-Navajo

speak the language in 1942,

making the odds of a Japanese soldier

being able to understand Navajo virtually zero.

When the U.S. military hears

about Johnston's idea, they take notice.

He's asked to come in and put his idea to the test.

In February 1942, Johnston assembles

four Navajo men at Camp Elliott in San Diego.

Under the scrutiny of the top brass,

the Navajo sit in separate offices

and are made to relay half a dozen simple messages

to each other via telephone.

The Navajo test subjects perform flawlessly.

The messages are relayed far faster

than they could have been encoded and decoded,

and there's not a single mistake among them.

Johnston's big idea gets the green light.

Now he needs to scale it up for battle.

Hundreds of Navajo volunteer for service,

and they're rapidly given basic military training.

But pretty soon, a problem arises.

The Navajo language is almost a thousand years old,

but this language doesn't contain

any words for modern warfare.

To get around the missing words,

Johnston proposes using everyday words

that have military meanings.

So for example, "whale" became the word

that was used for battleships.

In November 1942,

the first 13 Navajo code talkers

are deployed to the Pacific.

It's finally time to put Johnston's idea

to the ultimate test in the heat of battle.

Chester Nez and Roy Begay

are two of the first Navajo code talkers

who arrive in Guadalcanal.

And they have a literal trial by fire.

On the 7th of November,

Chester and Roy's platoon comes under attack

as they try to take an airfield.

They are pinned down.

A runner comes with an urgent message

to call in an artillery strike.

While bullets and mortar rounds whiz overhead,

Chester begins transmitting the message

to call in the artillery strike

in his native language of Navajo.

Seconds later, artillery buzz overhead,

neutralizing the Japanese machine gun nest

holding them down.

The entire message

took just 20 seconds to send and receive.

If sent using standard military code,

it would have taken 30 minutes,

by which time Roy and Chester's company

would have been annihilated.

Roy and Chester's commanding general contacts his superiors,

saying this Navajo code is terrific.

The enemy never understood it.

We don't understand it either, but it works.

Send us more Navajos.

After the arrival of the Navajo code talkers,

the American forces go on to win

the Battle of Guadalcanal.

It's a decisive point in the fighting

in the Southwest Pacific.

The Navajo code talkers

continued to play a critical role,

including in pivotal action at Iwo Jima and Bougainville.

And the Japanese never managed to figure out

their ancient language.

After the war is over, code talkers

don't get the official recognition they deserve.

While part of that is due to race relations at the time,

a larger part is due to the oath

that the code talkers took,

promising to keep their operations secret

in case they were ever called upon in time of need again.

Only in 1968 is

the service record of the code talkers declassified.

Then, in 2008, President George W. Bush

signs the Code Talkers Recognition Act,

and the hidden heroes of the Pacific War

are finally given their due.

After Pearl Harbor, a U.S. codebreaker

discovers Japan is planning an even more devastating attack,

only he doesn't know where.

If he can't crack the Japanese cipher,

then the whole U.S. Pacific Fleet could be destroyed.

On December 7, 1941,

the Japanese launch a surprise attack

on the U.S. fleet at Pearl Harbor,

claiming the lives of over 2,400 Americans.

Pearl Harbor ranks with 9/11 as the worst

intelligence failure in American history.

Captain Joseph Rochefort

is the head of the codebreaking unit

at Pearl Harbor.

Rochefort vows to make sure the U.S. will never

be ambushed like this again.

In the aftermath of the attack,

Rochefort and his team are tasked

with cracking the notorious Japanese code JN-25.

The code uses a huge codebook to translate

common words and phrases into individual five-digit numbers.

From there, there's

an additive codebook that then scrambles

those numbers yet again.

This dual system makes it just about impossible to break.

Rochefort and his team

began studying the mass of Japanese communications

from the days leading up to Pearl Harbor.

Rochefort discovers that, in the rush before Pearl Harbor,

the Japanese coders got careless.

They began transmitting codes using

an additive book that had already been

partially cracked by the U.S.

This allows Rochefort to spot something else.

It seems that when the Japanese are discussing

target locations, they use the prefix A

to represent U.S. interests in the Pacific.

AI seems to stand for Oahu.

AH is Hawaii; AK, Pearl Harbor.

Soon after Rochefort has discovered these

two-letter codes, a fresh set of intercepts

arrive mentioning a fourth two-letter code location.

Japanese air commanders are inquiring about wind speed

for an upcoming attack on AF.

What the Americans don't want is to be caught

in some kind of trap.

It's so very important to know exactly where AF is.

Rochefort is reading

the messages over and over, and then it hits him.

He looks at who the message was sent to

and who it wasn't sent to.

And Rochefort notices that there was

one military branch that didn't receive the message,

submarine commanders.

If submarines are not included,

this attack is likely to be an air attack,

meaning AF needs to be within range of the Japanese base

on the Marshall Islands, where their

aircraft carriers are harbored.

That narrows down AF to only a few possible locations.

By process of elimination,

he knows the attack can't be on the Hawaiian Islands

because they have a code name assigned to them.

And so, narrowing it down,

he knows that AF has to indicate

the American bases on Midway.

Rochefort believes he's cracked the code

and knows where the attack will happen.

But it all counts for nothing if he

can't convince his commanders.

The stakes couldn't be higher.

It's crucial that the Americans

hold on to Midway.

After the losses already suffered at Pearl Harbor,

to lose Midway at this point would kind of be like

the 1-2 punch that really makes the knockout.

Rochefort has this sense that AF is Midway,

but he can't prove it.

And there's no way that he is going to advise Admiral Nimitz,

who commanded the Pacific Fleet,

to send out America's remaining carriers

to ambush the Japanese on that kind of hunch.

So he comes up with a plan.

Rochefort arranges for

Midway's garrison commander to send a fake message,

saying that they're low on fresh water.

Now, if the message is sent uncoded,

the Japanese will immediately realize it's fake.

So Rochefort gets the message sent

using a U.S. cipher that he knows the Japanese

have already cracked.

Then Rochefort waits.

48 hours later, he gets the response he was banking on.

Rochefort's team decodes a message

about the imminent attack on AF,

and it specifically states AF is low on water.

This is the clincher Admiral Nimitz needs.

AF is Midway.

This is the kind of intelligence

that commanders dream of.

Nimitz understood that, if he got it right,

the Japanese Pacific fleet would be devastated.

Somebody was headed for an ambush.

Would it be the Americans or the Japanese?

Wasting no time,

Admiral Nimitz sends three aircraft carriers

with 117 aircraft to await the Japanese.

On June the 4th, 1942,

they catch the Japanese fleet entirely by surprise.

The Battle of Midway is resounding naval victory

for the United States.

The United States sends to the bottom of the Pacific

four Japanese aircraft carriers,

thus neutralizing the Japanese threat in the Pacific.

Midway is such an incredible triumph

that everyone wants a piece of the glory.

And credit for cracking JN-25 is

ultimately claimed by the Director of Naval Intelligence.

And Rochefort's role is basically

forgotten from history.

Only in 1985, when a book is published

by a former colleague, is Rochefort finally

revealed as the unsung hero

who stopped a second Pearl Harbor.

The following year, he is posthumously awarded

the Navy Distinguished Service Medal.

When a U.S. POW in North Vietnam's

Hanoi Hilton wants to reveal to the world

that he's being tortured,

he does it without his captors noticing.

Blink, and you'll miss it.

Commander Jeremiah Denton

is an experienced and respected career aviator

in the U.S. Navy.

In 1965, he's flying a bombing mission

when his airplane is struck by anti-aircraft fire.

Denton manages to bail out and parachute to safety,

but he's quickly captured by Vietnamese forces

who take him to the infamous prison Hoa Lo.

The prison is better known among U.S. POWs

by its nickname, the Hanoi Hilton.

But there's nothing luxurious about the conditions

Denton checks into.

Hoa Lo is a horrid situation for the aviators

that are held there.

The Vietnamese classify American aviators

as air pirates, and they claim that they are not protected

by the Geneva Convention.

They are kept in a prison facility

where they're often subjected to harsh interrogation

and torture.

They're not allowed to communicate

with one another,

and any attempt to speak to a fellow prisoner

will probably result in a pretty nasty beating.

Denton understands keeping his sanity

intact relies on one thing.

He must find a way to connect with his fellow inmates.

Denton discovers that the POWs

have already found a way to communicate

without using spoken words.

They pass messages by tapping on their cell walls

in Morse code.

Through their secret communications,

Denton is able to incite a campaign of resistance.

But the guards identify Denton as the ringleader.

He is beaten and brutally tortured.

In October 1967,

Denton is moved to another prison unit

reserved for the inmates deemed to be troublemakers.

This one has the less ironic nickname, Alcatraz.

Here, the tap code won't work.

Alcatraz is a much harsher system,

and the guards will inflict punishment

on any individual who appears to be

communicating via Morse code or any other form

of encryption system.

Denton is desperate to communicate

with any of the other POWs there,

but he's terrified of any more torture.

So Denton starts devising an entirely

new code based on the sounds he hears all around him,

and that the guards would never think twice about--

coughs and sniffs.

Due to the terrible conditions,

practically all the inmates

have some sort of respiratory problem.

So coughs and sniffs will easily

fall under the cover of the current

environmental conditions.

With this new code, a single cough means one,

a cough or a sniff twice means two,

and so forth and so on.

Using a standard five by five grid,

where each letter is designated two numbers

between one and five,

the airmen are able to spell out full messages

to each other without anyone ever detecting it.

Denton wants to speak to more

than his fellow prisoners.

What he dreams of is to be able to tell

the outside world of the brutal conditions

being endured by POWs.

One time out of the blue,

Denton got an incredible opportunity.

After nearly 10 months of captivity,

the guards informed Denton that the following day

he is to be interviewed in front of a global audience.

Denton is told that this

media appearance is very important,

and he is warned to be on his best behavior.

It's entirely likely that, if he doesn't comply,

he'll be killed.

How can he tell the world what's happening

without his captors finding out?

Denton's solution is ingenious and so sensitive,

it remains secret for years to come.

Morning comes, and Denton

is taken out of his cell, blindfolded,

and driven away from the prison.

He finds himself in a nicely-appointed room,

sitting in front of a Japanese journalist and crew.

Denton has no idea how

he can subvert this interview.

But then it's action.

The lights go on, and he's temporarily blinded,

and he squints and blinks to try to avert

the light from his eyes.

And then the idea comes to him.

Denton is answering the questions

in the way that his captors want him to.

But his eyes are telling a completely different story.

Denton's blinking is actually spelling out

a message in Morse code.

The message spells out one word, "torture."

In plain sight, with the world watching,

Denton spells out "torture" in Morse code again and again,

a single word that says it all.

The North Vietnamese don't notice what Denton is up to,

and the broadcast is actually transmitted worldwide.

This is big news.

It's the first indication that

the United States has that North Vietnam

is violating the Geneva Convention.

Denton has no idea

if his message has been heard.

The U.S. authorities never make public

his blink code, fearful that it would lead

to more extreme consequences,

like more beatings or even execution.

He doesn't find out that his code

was actually received until 1973

when he's finally released.

A year later, Denton is awarded

the Navy Cross for his conduct during captivity.

But the full story of his ordeal

remains unknown until 1975,

when he publishes his memoir, "When Hell Was In Session."

And now the world finally discovers the story

of Denton's courageous blinking code.

What if I told you that a key part of beating

the Nazi's unbreakable Enigma code

was a bunch of Ohio factory workers

who made cash registers?

It's a wartime secret so sensitive

that it remains under wraps for more than 50 years.

In the early 1940s,

it's open season in the North Atlantic

for Nazi submarine wolfpacks.

The German Navy is sinking vast numbers of Allied ships.

From the summer of 1940

into the spring of 1941, hundreds of allied ships

are sent to the bottom of the Atlantic by German U-boats.

It's what the U-boat crews gloatingly call the happy time.

The secret weapon behind all this

is the Enigma device, a code machine the Nazis used

to encrypt orders to their submarine fleet.

If the Allies are to escape the U-boat attacks,

this code needs breaking.

But that's no easy task.

The Enigma machine is a typewriter-like device

that's used to encrypt messages and then unencrypt them

so they can be read normally.

For the process to work, both the sending and receiving

Enigma machines have three rotors

that have to be set to the same configurations.

And those are determined by using the key from a code book.

Unless you had the code book

and the setting sheets,

it is impossible to solve this by simple trial and error.

Then, in 1941, the British

have a major stroke of luck.

Their Navy captures an enemy U-boat

with an intact Enigma machine plus codebooks.

Now they are able to use their own decryption device,

which they call the bombe.

Overnight, they can now listen to encrypted

German communications. U-boat patrols are tracked.

Thousands of lives are saved.

But nine months later,

the German Navy decides to ramp up their security.

In February of 1942, the Germans quietly

roll out a new version of the Enigma machine

that has now a new fourth rotor.

Adding that single extra dial results in the number

of extra settings possible for encrypting the codes

increasing exponentially.

There are now 92 septillion different ways

to set up a German 4-rotor Naval Enigma machine.

It's a complete disaster for the Allies,

and they are completely locked out

of German Naval-encrypted communications.

U-boats basically go on the rampage again.

The British need a much faster

version of the bombe.

And that means not having to design

a mechanical decryption device,

but an electronic one.

The British are struggling to produce these machines,

so they turn to the United States,

and they ask for assistance.

Washington starts looking for someone

to build this new, improved bombe.

They need a visionary engineer with a team

of electronics experts in a vast manufacturing space.

They find all three in Dayton, Ohio,

at the National Cash Register Company,

or NCR.

The NCR is a world leader in electronics,

and they just invented the world's first

electronic accounting machine

that runs at a million pulses per second, a megahertz.

NCR has an enormous

production facility in Dayton.

They're led by Joseph Desch, an engineer

who has an intrinsic grasp of the potential of electronics.

Desch designs a way

of scaling up the British bombe,

utilizing the might of American engineering.

The biggest issue is it comes with an incredible price tag,

around $4 million each.

It also weighs over 2 and 1/2 tons.

So it needs to be built in a special room of the NCR

with one of the first steel-reinforced

concrete floors in the United States.

The Navy signs off on the costs,

and Desch's team gets building.

The process is relentless,

with the team working seven days a week.

Finally, on May 28, 1943,

after 11 long months, Desch's super sized bombe

gets its first test.

Inside the NCR,

Desch switches on the machine.

And he feeds it an Enigma M4 message.

The machine starts up.

It begins to whine.

And then the machine stops.

It seems like an electrical short circuit,

and the teams are deflated.

But suddenly it springs back to life.

And incredibly the machine scores a hit.

It prints out the precise key used to encipher the message.

They then use that key to set the rotors

on their own Enigma machine.

They can then decipher the code and reveal

the original message.

Desch has done it.

He sends the results direct

to the codebreakers in Washington.

Soon, Desch's machines

are being put to work decrypting German messages.

The Americans and the British are actually

decrypting Enigma messages faster

than the German recipients are.

After NCR and its decryption machines

start going into action,

the tide turns against the German U-boat commanders.

It stops being a happy time,

and it starts becoming a Nazi-hunting time.

For over 50 years,

the Dayton codebreakers' contribution

to breaking Enigma remains classified.

Desch and the women who made the U.S. bombe

take their secrets to the grave.

Only in 1995, after a campaign by Desch's daughter,

is their role finally acknowledged.

It's 1968.

Someone is selling the U.S. Navy's

top secrets to the Soviets,

and the Navy brass have no idea it's even happening.

When the truth is finally revealed after two decades,

it's not by the FBI or the CIA.

It's by a disgruntled spouse.

Senior U.S. Naval officials are a bit troubled.

Time and again, their opponents seem to gain the upper hand

on them and anticipate their moves

with almost clairvoyant skill.

From tracking their subs in the Atlantic

to eventually dodging bombing raids in Vietnam,

they sense that something is up.

The U.S. has no idea how this is happening.

It's as if the USSR has cracked U.S. Naval codes.

To U.S. commanders, that's a ludicrous suggestion.

At this time, the U.S. Navy uses

one of the world's most advanced coding machines,

known as the KW7.

It is one of the first fully electronic coding machines,

faster and more secure than ever before.

In order to break this code,

the enemy would have to get their hands on a KW7 machine

and have access to the key cards

that are necessary to operate it.

Those key cards, however, are changed out regularly,

usually about once a month.

And that means that even if the Soviets get their hands

on a machine, well, they'd still have

to have the latest key card in order

to figure out what a coded message says.

The Soviets have got their hands on some KW7s

after a U.S. ship was captured in North Korea.

But because the captured machines didn't have key cards

with them, the U.S. Navy believed that their code

was still secure.

A series of security breaches followed,

but the Navy is sure that this is just a run of bad luck.

It's not just bad luck.

It's something far worse.

Their top secret code is no longer secret.

The truth is first discovered

not by a cryptography specialist,

but by a housewife in Virginia.

Barbara Walker is the wife of John Walker,

a radioman in the U.S. Navy.

From the outside, they have a happy life with four kids.

They'd had money troubles before,

but now they live a very comfortable life,

a fact she puts down to John's rising career.

One day, Barbara Walker comes across something strange.

Tucked away in a closet is a grocery bag

stuffed with classified Navy documents.

And they've been hidden away there by John.

When confronted, Walker comes clean.

He's been stealing top secret information

and passing it to the Soviets in exchange

for millions of dollars.

Among John Walker's responsibilities

is taking care of these KW7 seven cards.

It's his duty and responsibility

to destroy the old ones and to safeguard the new ones.

But instead of doing that,

he's sending them to the Soviets.

Once they have the keycards,

the Soviets can decode the American messages

that they recorded over the previous month.

The Soviets then tunnel

their way into at least a million

encrypted Naval messages.

It's the most damaging

code breach in U.S. history,

and the Americans don't even know it's happening.

For over ten years,

John is able to intimidate Barbara

into keeping his secret.

Barbara is terrified of her husband's temper.

And she fears that, if she goes to the authorities,

she might lose her kids.

Over the years, John secretly drags more family members

into his twisted spy world, including

one of their adult sons.

Then in 1984, Barbara finally

breaks John's hold over her.

Barbara learns that John recently attempted

to pull their daughter in.

Even though the daughter refused,

she picks up the phone and calls the FBI.

She tells them about the drops,

what he's doing, how this all works.

As they listen, they see the KGB patterns at play.

Furthermore, as they investigate Walker,

it becomes clear that he has a little more cash

than one should for his station.

And he's taking some rather odd trips at odd times.

But they need more than

just circumstantial evidence.

So they attempt to catch John in the act.

In May 1985, the FBI trails Walker

to a wooded area near Washington, DC,

and watches him hide a package before leaving,

a classic dead drop.

Agents move in and retrieve the documents.

It's a goldmine.

Inside, they find 129 pages of classified material.

John is arrested at his hotel room just a few hours later.

Faced with the prospect of life in prison,

Walker does the only thing he can.

He makes a deal.

In exchange for his full confession,

he negotiates a more lenient sentence for his son, Michael.

John Walker is sentenced to life in prison.

For the Russians, this has been

a brilliantly simple strategy.

Their code breakers haven't had to crack anything.

All they had to do was crack open the checkbook.

The story explodes across the media,

along with Walker's stinging comment

that Kmart has better security than the Navy.

When the story of this domestic spy ring

goes public, it reveals huge flaws

in U.S. Naval security,

leading to the implementation of new security measures

to ensure this won't happen again.

It's New York in 1919.

A poker prodigy is lying in bed.

He's about to doze off when he's

struck by a flash of inspiration,

one that will help him crack a notoriously

difficult Japanese code.

In the aftermath of World War I,

American leaders have learned a hard lesson.

Information is power.

So if you can read other nations codes,

you can know what your enemies and even your friends

are really thinking.

Even in peacetime,

Washington doesn't want to rely on what other governments

choose to tell them,

so they decide to start cracking

other countries' codes.

The U.S. turns to an unlikely establishment

that publishes puzzle books from a nondescript brownstone

in New York City.

It's the secret headquarters of the U.S.'s

most advanced code-breaking operation,

called the Cipher Bureau,

an outfit so secret that it doesn't

even officially exist--

essentially, a U.S. government black op.

The young man who runs this

is Herbert Yardley, a prodigy with a flair

for numbers and puzzles.

In fact, he funded his education

through poker winnings.

Working for the State Department,

he secretly cracked a coded message,

meant only for the president in just two hours.

From there, Yardley's skills land him his own gig,

running the secret codebreaking team for the U.S. government

under its cover as a puzzle publisher.

Yardley and his Cipher Bureau

break all kinds of codes for the U.S. government.

Around 20 countries have their messages

cracked by Yardley's outfit.

The Cipher Bureau's most fiendish challenge

is cracking Japanese coded telegrams.

These are concerned with Japanese and U.S. negotiations

over a Naval Arms Limitation Treaty.

Yardley's Cipher Bureau is given

a collection of diplomatic cables from Japan to decode.

And this is a monumental challenge

because, even before you consider any encryption,

Japanese is incredibly complicated.

Instead of a 26-letter alphabet

like we have in English, they have the kana,

which is a collection of every possible syllable sound,

and there are 73 of those.

Despite the scale of the challenge,

Yardley vows that if he doesn't break the code

within a year, he will resign.

But after half a year, Yardley still can't

discern any real patterns.

He's really starting to wish he hadn't been

so hasty offering to resign.

Yardley dedicates so much of his time to breaking the codes

that he even starts dreaming about them.

And one night, inspiration strikes.

Suddenly, he's able to pick out

the Japanese word for Ireland in the telegrams.

Irish independence is in the news right now,

and the Japanese are discussing it

in their diplomatic telegrams.

Now it's like he has the corner of a jigsaw puzzle,

and he builds out from this,

cracking one syllable and then another.

And finally, after six months,

Yardley and his team have the Japanese code

completely defeated.

Yardley's work helped

secure a historic peace deal on U.S. terms,

and Yardley is rewarded with a Distinguished Service Medal.

But this becomes the high point

of his code-breaking career.

By 1929, after a series of funding cuts,

Yardley's Cipher Bureau is closed for good.

But because it didn't officially exist,

he's not able to draw a civil service pension.

So in the end, he ends up broke.

Feeling betrayed,

Yardley decides to publish a tell-all book

called "The American Black Chamber."

This effectively makes him the Edward Snowden of his time,

but it also makes him a small fortune.

He rakes in the equivalent of half a million dollars

in today's currency.

The U.S. government is outraged by Yardley

having gone from their secret puzzle nerd

to a rogue operator.

Yardley's book is an embarrassment

to the U.S. government.

Because of it, some 19 nations are alerted

that their codes have been broken

by the United States.

They can't throw him in jail because only limited laws exist

on spilling state secrets.

In March of 1933,

Congress amends the Espionage Act

by passing an act for the protection

of government records.

This prohibits the disclosure of anything sent in code.

These laws Yardley inspired

become informally known as the Official Secrets Act,

and they still bind government officials today.

From a prison cell to battlefields,

secret codes are a vital way nations hide information

from their enemies.

But for every locked door, there is a key,

and for every code,

a genius mind trying to crack it.