Modern encryption algorithms like RSA 2048 will remain safe from decryption by quantum computers for the foreseeable future, according to scientists from Fujitsu.
The researchers used the company’s Fugaku supercomputer and its 39 bit quantum simulator to simulate a quantum-based attack on RSA using Shor’s algorithm.
They found that to factor a composite number of 2048 bits would require around 10,000 qubits, 2.23 trillion quantum gates, and “a quantum circuit depth of 1.8 trillion”, Fujitsu said in a statement.
The researchers also found a sufficiently-large fault-tolerant quantum computer would need 104 days to crack RSA.
While warning against complacency, senior director of data and security research at Fujitsu Dr Tetsuya Izu said: “Our research demonstrates that quantum computing doesn’t pose an immediate threat to existing cryptographic methods”.
US academic Peter Shor proposed his algorithm for using quantum computers to attack cryptography in 1994.
Fujitsu was able to factor RSA-type integers from 15 to 511.
The researchers then generated quantum circuits to factor composite numbers from 10 bits to 25 bits, and used the results to estimate what would be needed to factor a 2048 bit composite number.
The research is to be presented at this week’s 2023 Symposium on Cryptography and Information Security (SCIS 2023) in Kitakyushu City in southern Japan.
