How cryptography holds the digital world together

Encryption is like the steel frame of a building. Invisible, but it holds everything together. Encryption is an absolute must in our digital age, and even if you think you don’t have skeletons in your closet, there’s good reason to keep your data secret.

“We all have things we want to hide, and for good reason. Information is valuable, so we should have the opportunity to decide for ourselves who can see what we have. It’s important, encryption helps with this,” says the associate professor. Tyge Tiessen of DTU Compute.

We usually say that not encrypting the communication is like sending an open postcard so that everyone involved in processing the message can read it. Then encrypting the message makes it something like a sealed envelope that only the recipient can read after opening.

“Without encryption, we would be back in the digital middle ages, as most of our communication systems are based on encryption,” says Tyge Tiessen.

You have to pay cash everywhere, you have to physically access the Citizen Service to change your address, you can’t shop at Nemlig.com or any other online store, and you can’t let unauthorized people send your email. Easy to read. In short, our entire digital everyday life will slowly collapse.

electromechanical encryption

Today most cryptography is done digitally with lots of zeros and ones, but cryptography used to be more difficult. Perhaps the most famous encryption machine in history was the Enigma, used by the Germans during World War II to send secret messages, where each letter typed into the machine was electromechanically transformed into another letter. It is believed that there are only about 300 Enigma Machines left in the world, and DTU has one of them.

Enigma used a rotor that spun when one of the machine’s keys was pressed, changing a letter to another through an electrical circuit, which then lit up in the Enigma machine. Knowing the rotor’s starting setting makes it easier for the recipient to decipher the message.

“Enigma was not a unique method of encryption. There were other similar encryption devices, but the way it was broken was very important to us,” says Tyge Tiessen.

The British team led by Alan Turing, who cracked the Enigma, has developed a specific machine called the Bombe that automates the code-breaking. This allowed the British to decipher nearly all of Germany’s encrypted messages towards the end of World War II. Believed to have shortened World War II by up to two years and saved millions of lives, Turing’s work laid the foundation for modern computers.

Christian Majenz, Assistant Professor of Cryptography at DTU Compute, said:

“Modern cryptography is simpler and more complex. Much harder to crack than Enigma, but at the same time very easy to implement on a computer.”

Today many non-military enemies

Cryptography used to be primarily used by the military, but today it has permeated every corner of society, and this poses a challenge.

“Today, we use encryption in multiple contexts, so we have even more enemies. Enemies will discover your network is insecure and hack it to see what you can do. It could be a neighbor who discovered what was going on,” says Tyge Tiessen.

Therefore, from private companies to public institutions, banks, utility companies, and individuals, everyone needs encryption as a bulwark against hackers. As whistleblower Edward Snowden’s revelations show, even law-abiding citizens risk being monitored, so telecom services are starting to use encryption that is virtually impossible to monitor. .

Quantum computers change everything

But in the future, with quantum computers capable of solving complex problems where even the fastest supercomputers fail, all encryption could be broken. It’s a bomb ticking beneath our digital society.

“This is the transition to post-quantum cryptography,” said Associate Professor Christian Majenz, who conducts research on precision quantum cryptography at DTU Compute.

“We are trying to develop cryptography before the advent of quantum computers, because otherwise we could use quantum computers to access all existing data. Once you build it, it’s like Lego bricks that you can build.”