We use it everyday and we certainly rely on it.
Although cryptography began thousands of years ago, mathematical analysis
of encrypted communications has effectively altered the course of history.
The most important Japanese code in World War 2 was used by the Japanese navy.
And the breaking of that code turned out to be the most significant source
of intelligence information available to the allied forces.
Japanese navy made several fundamental blunders in the development of the code.
Instead of having a 100,000 possible code book entries the maximum numbers you can have was
33,334 cause that's the number of multiples of three with five digits.
That turned out to be an absolutely critical blunder because it enabled the codes
to be broken steadily in time for the famous Battle of Midway in the middle of 1942,
so the American navy knew exactly what the Japanese battle plan would be.
[ airplanes, gun fire ]
Suddenly, the trap is sprung.
The invasion forces were hit, and hit, and hit again.
In World War 2 the Germans needed a mechanism to automate cryptography.
The invention of the Enigma, an electromechanical rotor machine,
made it easy for operators to just type in a daily key to encrypt their message,
which the other end could then de-crypt.
The clever mathematicians at Bletchley Park in the UK, including Alan Turing,
the father of computers, managed to break the Enigma.
I'm head of the Crypomathematics Research Discipline in the Defence Science
and Technology Organisation DSTO and our role is to support defence research into cryptography
and crypt analysis to support defence future security and Australian national security.
Defence to do its role needs to ensure that they can communicate effectively [yeah cheers thanks]
and securely [comms on maintaining in the vicinity, over]
troops overseas on dangerous operations need to be able to communicate to their base
[ on mission] And so all of those links are need to be real time
and secure otherwise peoples lives are jeopardised [Victor Tango 4 2 5 2] What came
out after World War 2 which revolutionised cryptography was a system called RSA,
the initials of the three people who developed it.
Traditionally you had symmetrical encryption, you had to have the same key,
the breakthrough really was in coming up with this idea of an asymmetric algorithm
where you needed two different keys one of which you could make public the other one so long
as you kept it secret you could be assured
that the communications people were sending you were secure.
It's quite easy to multiply 2 numbers together, it is a much harder problem to look
at a huge number and ask what two numbers were multiplied together to form that number.
So to make the RSA problem as hard as possible you create these two secret prime numbers you
multiply them together, you get a very big composite number which means it can be broken
up as product and you're the only one that knows how to do that.
Pierre de Fermat proved his little theorem in 1640.
It is an important component in proving that RSA cryptography works.
I'm a principal security consultant in the information security group at Westpac.
Cryptography and banking is very important in today's society.
It gives us the ability for us to trust the customer, to manage risk, to reduce fraud.
If you look at a modern credit card you'll see a little gold chip on the card
and on that chip is special circuitry that enables information to be encrypted
and decrypted in a very safe way.
The beauty of modern cryptography is that it is invisible.
An example of that would be using internet banking.
The customer's browser and our internet banking server talk to one another.
All communications between the browser and the server are encrypted.
For certain customers of Westpac that transact in very large amounts of money,
we augment the internet password with an additional layer
of security we use an RSA token device that we give to the customer.
You'll see 6 numbers displayed on the front of that token.
The number is derived from the time of day
and also a secret encryption key that's unique to every token.
Those 6 numbers change every 60 seconds and that number can only be used once by the customer
to log on or authenticate with our server.
Without that mathematics the cryptography would not be possible and without
that cryptography modern banking would not be possible.
Our business is the application of cryptography to solve real world problems
on high speed optical communication systems.
So our customers tend be people who care deeply about the security of their information.
That includes military and defence type organisations, all branches of government,
the financial sector, in the industrial sector, in the mining infrastructure.
And we have to use symmetric rather
than asymmetric encryption algorithms because they're much faster.
We have to transfer securely the encryption key from the sender to the receiver
across the network and to do that we do use a symmetric RSA encryption in our products.
We use AES 256 bit symmetric encryption to encrypt the data keys and we use RSA encryption
with the key size of 2048 bit to securely exchange those data encrypting keys
across the network The challenges aren't going away.
Networks are getting faster, the bad guys are getting cleverer, it's really a constant war
between the code makers and the code breakers so we need the best and brightest minds
to help us with that problem in the future.