The clash between Quantum Computing and Cryptography is one of the most exciting and critical technological issues of the 21st century. For decades, modern digital security has been based on mathematical problems that are considered practically unsolvable by classical computers. Algorithms such as RSA and elliptic curve cryptography protect banking transactions, state secrets, medical data, and our everyday communication on the Internet. However, the development of Quantum Computing threatens to overturn this foundation of security.
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Unlike classical computers, which rely on bits with values of 0 or 1, quantum computers use qubits, which can exist in superpositions of states. Thanks to phenomena such as superposition and entanglement, quantum computers have the potential to solve certain problems exponentially faster than traditional ones.
In 1994, mathematician Peter Shor presented Shor's algorithm, which theoretically demonstrated that a sufficiently powerful quantum computer could factor large numbers in polynomial time. Since the security of RSA relies precisely on the difficulty of factorization, the practical implementation of such a quantum system could render current public cryptography vulnerable.
Companies like IBM and Google are investing huge sums of money in developing quantum computers with ever-increasing numbers of qubits and improved stability. While today's quantum systems are not yet powerful enough to break the cryptography used on the internet, progress is steady.
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In 2019, Google announced that it had achieved “quantum supremacy” on a specialized problem, proving that quantum computers can outperform classical ones on specific tasks. While this didn’t have a direct impact on cryptography, it showed that the technology was maturing.
The risk is not just for the future, but also for the present. There is the “harvest now, decrypt later” scenario, where malicious actors harvest encrypted data today with the expectation that they will be able to decrypt it when quantum computers become powerful enough. This is particularly worrisome for information with long-term value, such as government records or medical data.
In response to this threat, the research community is developing so-called post-quantum cryptography. These are cryptographic systems based on mathematical problems that are considered resistant to both classical and quantum computers, such as lattice-based problems. But the transition is not simple. It requires upgrading infrastructure, protocols, and devices worldwide, which can take years.
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The showdown between quantum computing and cryptography is not just a technical challenge but a geopolitical and economic battle. States and multinationals are competing for the lead, knowing that whoever first achieves practical quantum supremacy will have a strategic advantage. The question is not whether the quantum era will come, but when and how ready we will be for it.
