The time required for a quantum computer to break a specific encryption algorithm depends on several factors, including the algorithm itself, the strength of the encryption, and the capabilities of the quantum computer. Currently, there is no universal quantum computer powerful enough to break widely used encryption algorithms in a practical timeframe.
To give you an idea, let's consider the most commonly used encryption algorithm, RSA, which is based on the difficulty of factoring large composite numbers. Breaking RSA using classical computers is a computationally intensive task, as it requires factoring large numbers into their prime factors. The security of RSA relies on the assumption that factoring large numbers is a difficult problem.
Quantum computers have the potential to break RSA and other public-key encryption algorithms more efficiently than classical computers using an algorithm called Shor's algorithm. Shor's algorithm utilizes the quantum properties of superposition and entanglement to perform prime factorization more efficiently.
The time required for a quantum computer to break RSA or any specific encryption depends on the number of qubits and the error rates of the quantum computer. The larger the number of qubits and the lower the error rates, the more powerful and capable the quantum computer is.
the largest quantum computers have been able to factorize relatively small numbers using Shor's algorithm. For example, in 2019, IBM announced that they had used a quantum computer with 53 qubits to factorize the number 291311.
However, breaking 16-digit RSA encryption (assuming it refers to a 16-digit key length) is still beyond the capabilities of current quantum computers. To break such encryption, it would require a significantly larger and more stable quantum computer than what exists today.
It's important to note that quantum-resistant encryption algorithms, also known as post-quantum cryptography, are being developed to withstand attacks from quantum computers. These algorithms are designed to be secure against both classical and quantum attacks, ensuring the long-term security of sensitive information.
The timeline for when a quantum computer will be capable of breaking widely used encryption algorithms is uncertain. It depends on the progress of quantum hardware development, error correction techniques, and advancements in quantum algorithms.