Even if quantum computing destroyed the SHA-256 algorithm, a community consensus to build a new hash function would be possible in Bitcoin.
by Paulo Márquez December 30, 2024 Reading time: 6 minutes.
The post-quantum era of bitcoin is a topic of discussion following the latest advancement in Google's chips.
Bitcoin could change its hash algorithm on the fly in case of a break of the SHA-256.
Recently, the tech giant Google launched a quantum chip called Willow. The processing capability of this chip has been attractively described for marketing, saying that it can solve a mathematical problem in 5 minutes 'that would take a supercomputer 10 septillion years (that is, 10^25), a number that far exceeds the age of the Universe.' Despite this technology being in the experimental phase and lacking practical applications, its existence is considered crucial for the future of computational systems and cryptography.
Satoshi Nakamoto had already foreseen something like this in 2010 when he imagined the possibility that the SHA-256 algorithm could be destroyed. The creator of Bitcoin does not specify what or how this hash function could be destroyed, but he outlines the consequences of any technology rendering this algorithm obsolete.
SHA-256, whose name is Secure Hash Algorithm 256, is a cryptographic function that converts any block of data into a fixed-length character string of 256 bits. This algorithm has two characteristics that make it highly secure.
One is that it possesses irreversibility, as the original data cannot be recreated from the data encrypted by the hash in reverse. Another is that it is resistant to collisions: it is designed to prevent two different inputs from producing the same numerical string. The collision or repetition of these numerical series would have consequences such as replication of bitcoin addresses, which would undermine the overall functioning of the network and its ability to safeguard digital ownership.
According to Satoshi, SHA-256 was already 'strong enough' in 2010, sensing that this algorithm could remain valid for several decades unless a massive attack on the network occurred. It is a reality that it has maintained this validity for a decade and a half, and it would have to last at least two more decades for the prediction of the creator of Bitcoin to come true.
In any case, Satoshi considered that, if there existed a technology capable of breaking the hash function, such as quantum computing, whose processing power is superior to everything known today, it would not mean the end of the world for Bitcoin, which is an open, free system and can be modified on the fly to circumvent difficulties of all kinds...
