Analysis: 128-bit symmetric encryption remains secure, quantum computing mainly threatens asymmetric cryptographic systems

According to Odaily, cryptography engineer Filippo Valsorda wrote that the impact of quantum computing on current encryption systems is mainly concentrated on asymmetric algorithms (such as ECDSA, RSA, etc.), while its effect on symmetric encryption (such as AES, SHA series) is limited. The Grover algorithm does not substantially weaken the security of 128-bit keys in practical scenarios.

Although the Grover algorithm can theoretically accelerate brute-force attacks, it is difficult to parallelize, and the actual cost of an attack is extremely high. Even under ideal quantum computing conditions, the resources required to break AES-128 are far greater than the cost of attacking elliptic curve encryption using the Shor algorithm.

In addition, standard institutions, including the United States National Institute of Standards and Technology, unanimously believe that AES-128 still meets post-quantum security requirements and does not need to be upgraded to a 256-bit key. Industry opinion holds that focusing resources on replacing asymmetric encryption schemes vulnerable to quantum attacks is currently a more pressing task.