Potential risks of quantum computation (2)


Ken Becher

Jul 26, 2021

The risks of quantum computation vary with the type of cryptographic algorithm:

Symmetric keys are considered to be quantum-resistant under certain circumstances. The current security standards recommend the use of AES algorithm with a 256-bit key for symmetric encryption, which is called AES 256. An attacker would have to try 2,256 combinations to crack a 256-bit AES key with brute force. A traditional supercomputer will take more than 7 billion years to do this, while a quantum computer can reduce the complexity of cracking symmetric encryption keys by half. However, even a quantum computer still needs to run for millions of years to crack an AES key, which makes most experts believe that this algorithm is quantum-resistant at present.

Hash functions are also considered to be quantum-resistant under certain conditions. Hash functions can generate a unique fixed-size code based on any input, and the novelty is that they are almost impossible to reverse. If a certain hash code is given, it would take thousands of years to generate the input of the same code. A quantum computer can reduce the time it takes to reverse the hash function from 2n to 2n /2 (“n” is the number of bits used for hash output). As a result, a longer hash function usually produces a 256-bit output, which is considered quantum safe and is expected to remain as the current recognized standard.

Asymmetric keys (public keys) may be eliminated in the field of quantum computation. In theory, by using Shor's algorithm and related optimization, a fully functional quantum computer can crack an asymmetric key in just a few hours.


Special for You

Privacy Policy | Terms of Use

Copyright 2019 - 2023

Contact us at : [email protected]