Privacy and Security

We’ll have to upgrade our security if we want to be able to communicate securely.

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You're already in the 7th track! This means that after this one, there's only one more left to complete. Keep going!

Enter Jaya Baloo.

Jaya is recognized as one of the 100 most influential people on security issues worldwide. And she's been keeping her eye on quantum for some time now.

So, let's talk about cyber security some more.

And we'll use an everyday app that most people count on for their personal communication.

Just like Alice and Bob.

You can see them in this picture. They are good friends and they like to send each other text messages.

It means that Bob's message is made unreadable while it is on the way to Alice.

Using a clever algorithm his text, all the letters are temporarily scrambled. We call that ‘encryption’.

So, when a hacker is able to intercept the message on the Internet.

He or she can only see the scrambled message. Your secrets are still safe.

And when Alice gets the message, it is converted back into readable text.

That’s possible because she receives a digital key with the message. This key allows Alice’s phone to reconstruct the encrypted message.

Making such an encryption algorithm isn’t easy.

The way in which you mix up the letters, cannot be too obvious. You don’t want criminals to be capable of solving your encryption with a few guesses.

It’s a bit like computers having to solve very difficult sudokus. Welcome to the world of cryptography!

Here's Christian Schaffner.

As a professor of theoretical computer science he is fascinated by cryptography.

So, how can a hacker try to decrypt a message?

For that we have a little exercise for you.

What you’ve just done is a form of decryption.

In a rather simplified situation WhatsApp would use '403' as the secret decryption key. In that case Bob's message sent with his key (13) can only be read by people who's key multiplied by 13 gives 403.

For a criminal to 'guess' that 31 was the right key, would be easy.

That's why WhatsApp and banks use extremely large prime numbers for their multiplications. If you want to go out and write a computer program that tries out all kinds of numbers, it would take thousands or even millions of years before it guesses the right number.

Remember?

Remember how Koen told us that a quantum computer could solve very complex problems in a short time? And then Stacey told us about algorithms for quantum computers.

Imagine what would happen if a quantum computer is used to decrypt messages...