A June 24 report explains that researchers at Shanghai University have successfully cracked a 22-bit RSA key. This meant breaking an encryption system widely used to protect sensitive data, such as banking transactions or digital communications.  

Although 22 bits is a modest length compared to the 2,048-bit RSA keys used in practice, the Shanghai University's success suggests a step forward in the application of quantum technologies.  

The experiment was based on converting the factorization problem (which underpins RSA) into a combinatorial optimization problem. RSA, an asymmetric encryption system, secures sensitive data by using a pair of keys: a public one for encryption and a private one for decryption, whose security depends on the difficulty of factoring a large number into its prime factors. Classically, breaking an RSA key takes exponential time on traditional computers, but quantum computing, with algorithms like Shor 's, could reduce that complexity.  

However, the Shanghai University team opted to use a quantum annealing processor, developed by D-Wave Systems. This is a technique that uses quantum fluctuations to explore the solution space. By avoiding the deep circuitry typical of other quantum systems, this technique produces more optimal solutions. 

The report notes that the D-Wave Systems processor used more than 5,000 qubits (basic units of quantum information) to achieve the factorization.  Although it's not specified, it's understood that the publication refers to 5,000 physical qubits. In quantum computing, logical qubits are the most important because they guarantee error correction and long-term stability, each of which is composed of hundreds or thousands of physical qubits working together. 

The Chinese university's breakthrough doesn't mean RSA encryption is compromised today: current keys are resistant to attacks due to their exponentially larger size.  However, the experiment shows which improvements in quantum hardware and algorithms are bringing us closer to “Q-Day,” the day when current cryptography will be vulnerable. 

For Bitcoin, the impact is indirect, as it doesn't use RSA encryption. Bitcoin relies on ECDSA (Elliptic Curve Digital Signature) and SHA-256 to protect users' private keys and secure the network, algorithms that guarantee its current integrity.  Many analysts believe that quantum risk is still distant, such as Adam Back, a bitcoin developer and founder of Blockstream, who believes that the alleged danger is “one or two decades away” due to the current limitations of quantum computing.  However, other experts in quantum physics development warn that this danger could approach more quickly with ongoing technological advances.