Quantum, the world’s favourite science buzzword. This includes in computer science, where quantum computing has become of the hottest areas in research. But how does this new technology threaten the way we currently use encryption on the internet? Could the age of online banking be over, will cash make a comeback?
Although it feels a scary topic to approach, computer information can be stripped back to very simple core principles. We have all heard of binary, the language of computers. A single binary unit (a one or a zero) is what we call a bit. These binary bits are to computers what letters are to literature, the key to how they can process and store information.
Quantum computers are fundamentally very different, importantly they don’t use binary bits. A quantum bit is not strictly one or zero, but in fact a mixture, waiting to be confirmed. The details of how a quantum bit can be a mix of one and zero comes from physics that even Einstein described as “spooky”, so let’s leave the science and look at what these reimagined computers are capable of.
Imagine the classic game of two doors, one concealing a prize and the other nothing. This is a binary problem, if you want to guarantee finding the prize then you would of course have to open both doors. An ordinary computer would agree with you; to check both possibilities two actions must be made, and so two bits must be turned on or off. A quantum computer proceeds differently. It sends a signal at both doors, and the correct door amplifies this signal while the incorrect one dampens it. The quantum computer then opens the most likely door based on the amplified signal, which only requires one action. Importantly, the quantum algorithm never opens multiple doors at once. The process simply amplifies the door most likely to be worth opening, an incredibly powerful trick for certain problems which drastically reduces computation time.
So how does this all relate to banking? In the modern age, most transactions happen online rather than in the physical world, so encrypting people’s data is extremely important. Encryption is considered by many mathematicians an important issue of the modern age. This is because encryption works by hiding data behind hard maths problems, but importantly the sort of problems that would take a lifetime to solve. Realistically you need an access key. You might then wonder how a key is secure. This is because keys are the most protected thing in a computer system, hidden and disjointed; like finding a needle in a haystack, or more accurately a single atom in the whole universe.
With the simple door analogy, the improvement in computation time is clear. We can extend this logic to, say a million doors, and the quantum computer will still send out the signal that is either amplified or dampened. It won’t always pick the right door on the first try, but it massively narrows the search – turning an unfeasible task into a manageable one. This is a big problem for many modern encryption methods, maths problems that were regarded as impossible can now be solved much more quickly without a key.
Quantum computing is becoming a realistic and dangerous threat to banking security. That is why the international tech community is racing towards Post-Quantum Cryptography (PQC) – maths problems that can be used for encryption that are quantum-proof. The leading body for encryption standards is the National Institute of Standards and Technology (NIST), who released their three principal PQC standards in 2024. These are encryption methods they believe are safe for the future. While regulation changes to standards are set for 2035 by NIST, they emphasise that implementation should begin now.
Although quantum computers capable of breaking current encryptions are not imminent, the move to security is urgent, with PQC providing the foundations to protect us. Whether encryption can withstand the future of quantum computation is yet to be known, so maybe hold on to that cash for now.
“Quantum Computer Interior” by IBM Research is licensed under CC BY-ND 2.0.