A recent report by Google software engineer Craig Gidney has rekindled debate within the Bitcoin community about the risks that quantum computing could pose to the security of cryptographic systems, including those that protect Bitcoin (BTC).
In his study, Gidney claimed that a quantum computer could break certain cryptographic schemes up to 20 times faster than previously thought, a finding that raised concerns in the cryptocurrency ecosystem. However, his tests focused specifically on 2048-bit RSA cryptography, a widely used encryption system for protecting sensitive data, comparable to a mathematical lock that safeguards information in the digital world.
Faced with this scenario, Charles Guillemet, chief technology officer (CTO) of Ledger, the renowned company that created hardware wallets, made a technical clarification about the real impact of this report on Bitcoin does not use the RSA system on which Gidney based his latest studies as a security method.
Ledger executive's clarification regarding concerns
Guillemet took it upon himself to clear up any doubts that arose after the Google engineer's report: “Bitcoin doesn't use RSA. In fact, no serious blockchain does,” noted the Ledger CTO. It's worth clarifying here that Google's Gidney didn't mention that his study considered a threat to Bitcoin, but rather referred exclusively to RSA.
RSA (Rivest, Shamir, Adleman), named after its creators Ron Rivest, Adi Shamir, and Leonard Adleman, is an asymmetric cryptography system developed in 1977. This method uses a pair of keys: a public key, which is shared openly, and a private key, which remains secret. Its security is based on the mathematical difficulty of factoring extremely large numbers, products of two prime numbers.
In simple terms, RSA works like a digital lock: the public key encrypts the data, and only the private key can decrypt it. This system is widely used in internet protocols, such as HTTPS, to protect sensitive communications and data. However, Bitcoin and other networks do not rely on RSA for security. Instead, Bitcoin uses a cryptographic scheme based on elliptic curve cryptography, known as ECDSA (Elliptic Curve Digital Signature Algorithm). This system is also asymmetric, but is based on a different mathematical problem: the discrete logarithm problem on elliptic curves.
Essentially, ECDSA allows Bitcoin users to generate public and private keys to sign transactions and verify their authenticity, ensuring that only the owner of a private key can move their funds. For Guillemet, the danger that a quantum computer poses to Bitcoin security is far from a reality today.
Guillemet limited the impact indicated by the Google engineer
Gidney's report highlighted that a quantum computer could reduce the security of 2048-bit RSA up to 20 times easier than previously estimated, equivalent to going from a security level of 2^112 to 2^107.
That might sound alarming, but Guillemet did contradict Gidney on this point, explaining that the change is negligible: “Going from 2^112 to 2^107 in RSA security is like going from impossible to even more impossible,” he said. In other words, even with Gidney’s reported reduction, breaking RSA encryption would still be impossible for any computer, quantum or otherwise, to accomplish in a reasonable amount of time, according to Guillemet.
Furthermore, Ledger's CTO highlighted an even bigger obstacle: the lack of a quantum computer advanced enough to pose a real threat. According to Guillemet, for a quantum attack to be effective against any cryptographic system, it would require “a machine with millions of stabilized and error-corrected qubits. We're nowhere near that,” he pointed out.
As quantum technology advances, the debate over its impact on Bitcoin and other digital security systems is likely to continue. Some consider it a more immediate risk, while, like Guillemet, other experts have expressed an optimistic stance on the matter, such as Adam Back, who considers quantum danger unlikely for now.
