Quantum computers will acquire the ability to break classical cryptography in a relatively short period of time. At the end of last March, a group of researchers from the California Institute of Technology (Caltech), the University of California at Berkeley and the emerging company Oratomic published a preliminary scientific article in which they explored the capabilities of quantum computers of neutral atoms. These machines are an alternative to quantum computers with superconducting qubits and ion traps, and are still in an experimental phase.
These scientists have estimated that Shor’s algorithm can be implemented using a quantum computer equipped with between 10,000 and 20,000 qubits of neutral atoms. In fact, in their article they even propose a design with which it would theoretically be possible to break the Bitcoin encryption in a few days using 26,000 qubits of neutral atoms. In any case, these researchers are not the only ones who in recent months have alerted us to the ability of quantum computers to violate classical cryptography.
In that same period, Google’s quantum artificial intelligence group published a study showing that the elliptic curve encryption used by Bitcoin or Ethereum, among other cryptocurrencies, can be overthrown using far fewer resources than initially estimated. According to these researchers, a quantum computer with less than half a million physical qubits will be able to decipher the algorithms used by current cryptocurrencies in a few minutes. In short, the scientific community has agreed that classical encryption technologies will be vulnerable before the arrival of large-scale quantum hardware.
We can now protect our data
Cryptography is the art of protecting our information through mathematical transformations. In this way, an encrypted message is incomprehensible to anyone who does not have the correct key. For decades, Internet security has rested on a seemingly solid principle: certain mathematical problems are so difficult to solve that no conventional computer could attack them in a reasonable amount of time.
Post-quantum cryptography brings together a set of cryptographic algorithms designed to resist attacks from both classical and quantum computers.
However, as we have seen, quantum computers are going to overturn this premise sooner rather than later. Fortunately, we have post-quantum cryptography, commonly known as PQC by its English name (Post-Quantum Cryptography).
This technology brings together a set of cryptographic algorithms designed to resist attacks from both classical and quantum computers. The most important thing is that these algorithms run on conventional hardware. They do not require quantum computers to operate and are designed to replace current standards on the same processors we use today.
In 2024, the US National Institute of Standards and Technology (NIST) published an initial set of standards that includes a post-quantum key exchange mechanism and several post-quantum digital signature schemes.
The three standards published by NIST have clear functions. ML-KEM is based on the CRYSTALS-Kyber algorithm and is a key encapsulation mechanism. Its function is to establish securely encrypted communication channels, replacing the classic protocols that the browser and the operating system use today to protect our connections.
On the other hand, ML-DSA and SLH-DSA are digital signature schemes. They serve to verify that a message or file comes from who it claims to come from, without any quantum computer being able to falsify that signature. The three standards rely on mathematical problems that quantum computers cannot solve efficiently with current knowledge.
The good news is that we don’t have to wait for our operating system to update. Some of the most used applications have already incorporated these standards in a way that is transparent to the user. Encrypted messaging app Signal implemented ML-KEM-1024 in its PQXDH protocol in 2024. Since then, every conversation protects session keys with post-quantum cryptography without the user having to configure anything. It is the clearest example that the transition has already begun, and that it can be completely invisible to users.
How to encrypt your files with a certified tool
To protect the files stored on our computer, the most accessible and audited tool available today for home users is VeraCrypt. It is free, open source and compatible with Windows, macOS and Linux. Its encryption is based on AES-256, a symmetric algorithm that NIST maintains as a standard and that remains resistant to quantum attacks.
And the quantum threat does not affect all cryptography equally: Shor and Grover’s algorithms effectively attack asymmetric cryptography (RSA, elliptic curves, etc.), but symmetric cryptography with 256-bit keys retains sufficient strength against any quantum computer. In practice, AES-256 offers quantum security equivalent to 128 bits – enough to protect any personal file for decades.
Using VeraCrypt takes just a few minutes. Once we have downloaded it from its official website, the process consists of creating an encrypted container: a file that acts as a password-protected virtual disk. On the main screen we will select Volumes/Create New Volumeand then Create an encrypted file container.
The strength of symmetric encryption ensures that no next-generation quantum computer will be able to access content by brute force
Next, we will choose the location and size of the container, select AES as the encryption algorithm, and set a strong password. Once created, that container is mounted as if it were another unit of the computer. In this way, any file that we drag inside is automatically encrypted. When you unmount the volume, the data is unreadable to any person or machine that accesses the disk without the password.
To protect our passwords, the most reliable domestic option is KeePassXC. It is an open source manager, without connection to external servers and with periodic independent security audits. Stores all passwords in a locally AES-256 encrypted database that is only opened with a master password or additional key file. The cloud alternative is Bitwarden, which also encrypts data with AES-256 before sending it to the server. In both cases, the strength of symmetric encryption ensures that no next-generation quantum computer will be able to access the content by brute force.
Anyone who wants to complete this strategy can do so with Signal, which is available for Android, iOS, Windows, macOS and Linux. Installation does not require any additional configuration, and post-quantum encryption operates by default on each message and call from the moment both interlocutors have the updated application. There is no other widely used messaging application today that has adopted the standards approved by NIST this far in advance.
Be that as it may, the transition to post-quantum cryptography is not a question of the future: the algorithms are already available, the standards are approved and the tools are accessible to any user without advanced technical knowledge. Anyone who encrypts their files with VeraCrypt, manages their passwords with KeePassXC and communicates through Signal will today have adopted the same protection that large infrastructure operators are deploying on a global scale.
Image | Rafael Minguet Delgado
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