Recently, the technology giant Google launched a quantum chip called Willow. The processing capacity of this chip has been described in an attractive way for marketing, saying that it can solve in 5 minutes a mathematical problem “that would take a supercomputer 10 septillion years (that is, 10 25), a number that far exceeds the age of the Universe.” Although this technology is in the experimental phase and has no practical applications, its existence is considered decisive for the future of computing and cryptography systems.
Satoshi Nakamoto had already foreseen something like this in 2010, when he imagined the possibility of the SHA-256 algorithm being destroyed.. The creator of Bitcoin does not mention what or how this hash function could be destroyed, but it exposes the consequences of any technology making said 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 256-bit character string. This algorithm has two characteristics that make it highly secure.
One is that it has irreversibility, since the original data cannot be recreated from the data encrypted by the hash. Another is that it is collision resistant: it is designed to prevent two different inputs from producing the same number string. The collision or repetition of these numerical series would have consequences such as replication of bitcoin addresses, which would violate the integral functioning of the network and its ability to safeguard digital property.
According to Satoshi, SHA-256 was already “quite strong” in 2010, sensing that this algorithm could remain valid for several decades if a massive attack on the network did not occur.. It is a reality that it has remained in force for a decade and a half, and it would have to last at least two decades for the prediction of the creator of Bitcoin to come true.
In any case, Satoshi considered that, if there is a technology capable of breaking the hash function, such as quantum computing, whose processing capacity is superior to anything currently known, This would not mean the end of the world for Bitcoin, which is an open, free system and can be modified on the fly. to overcome difficulties of all kinds.
If SHA-256 were to break completely, I think we could come to some agreement on what the legitimate blockchain was before the problems started, fix it, and go from there with a new hash function.
Satoshi Nakamoto, creator of Bitcoin.
Selecting a new starting point for Bitcoin after the destruction of its algorithm would imply that all nodes and participants in the network would accept a chain as the true one, and they have the incentives to do so.
Satoshi then goes into technical details on how to preserve the network after a SHA-256 break:
“If the hash break occurred gradually, we could transition to a new hash in an orderly manner. The software would be programmed to start using a new hash after a certain block number. Everyone would have to update their bitcoin client at that time. “The software could save the new hash of all the old blocks to ensure that a different block with the same old hash cannot be used.”
Satoshi Nakamoto, creator of Bitcoin.
Other bitcoiners weighed in on the hash function and Bitcoin
Theymosa well-known figure in the Bitcointalk community who has served as the forum’s administrator since its inception, agreed with Satoshi that “broken crypto” could not be the end of bitcoin if the currency became popular, which it ended up happening.
Since the blockchain can be forked without losing too much data, modifications can be made to all aspects of BitCoin. If SHA-256 were violated, a new version of BitCoin would be released that would use a more robust hash function for addresses.
Theymos, Bitcointalk moderator.
known collisions for the year 2010, fifteen years after its publication, suggesting that this family of hash functions is quite robust and resistant to the passage of time, even if they become outdated.
Luke Dashjranother bitcoin developer who is still active, commented in 2011 that the solutions proposed by Satoshi and other commentators a year earlier were somewhat simplified. Especially because In a single year, Bitcoin had changed considerably:
“’Switching’ to a new hash means creating a new protocol (possibly derived from the existing one) and an entirely new network (possibly based on a genesis block that offers bitcoin funds to the SHA-256 addresses that had them pending). In 2010, there was only one customer, and reinventing everything may have seemed like an easy solution. But as of 2011, we are starting to see alternative implementations of Bitcoin, and by the time SHA-256 is broken, we will no doubt have many different possibilities.
Luke Dashjr, Bitcoin developer.
Both Satoshi and Bitcointalk contributors agree that the Bitcoin protocol, and especially its developers, They have the ability to fully preserve and move ownership records within the system while “uploading” the network over a new hash function.probably causing a protocol fork. This new hash function would be quantum computing proof.
Efforts in this direction have been made by cryptographers, and their results are the SHA-3 function, in whose family of algorithms there are at least a couple with more than 300 bits, and therefore capable of creating longer numerical series with a greater number of possible combinations.
But the most important series of developments to defend the crypto of the future comes from the “Post-quantum cryptography” (PQC), from which new hashing algorithms have emerged, such as those based on lattices (lattice-based), the hash-based cryptography, including modern versions of systems such as Lamport signatures and the Merkle signature scheme; and code-based cryptography.