In response to the uncertainty surrounding the launch of Google's Willow chip and analysts' views on its potential to compromise Bitcoin (BTC) security, the BIP-360 improvement proposal emerges as a possible solution. 

This proposal seeks to introduce a quantum-resistant transaction mechanism, ensuring compatibility with current systems and preparing Bitcoin for future cryptographic threats.  

Among those who believe quantum computing could affect Bitcoin is Chamath Palihapitiya, an engineer and venture capitalist. He explained that 8,000 Willow chips working together could pose a security risk to the Bitcoin network. 

He also said that within a period of “2 to 5 years”, cryptocurrency networks will have to adopt hash algorithms resistant to quantum computing.

In this context, Ben Sigman, CEO of Bitcoin Libre, a company that offers a BTC wallet , gave his opinion on how the implementation of BIP-360 would work. This Bitcoin improvement proposal, known as “QuBit”, was developed and presented by the developer Cryptoquick on June 8, 2024.  

What is BIP-360 and how does it work?

According to its document, BIP-360 is a proposed improvement to the Bitcoin protocol that introduces the P2QRH ( Quantum-Resistant Hash Payment) cryptography payment method and provides a transaction mechanism resistant to quantum attacks.  

Currently, the ECDSA  (Elliptic Curve Digital Signature Algorithm) algorithm is the encryption that Bitcoin uses to sign transactions and guarantee the security of private keys.  

With this current Bitcoin mechanism, funds are locked with ECDSA-derived public keys, which would be potentially vulnerable to quantum attacks. 

The risk would be given, according to Sigman, by the possibility that the elliptic curve cryptography (ECC) currently used in this network, such as the ECDSA algorithm, could be compromised.  

However, algorithms like Shor, which quantum computers could run on private keys, have the theoretical potential to compromise this system.   

BIP-360 would replace that mechanism, locking and unlocking users' funds with robust hashes , such as SHAKE256 or SHA-3, that would be immune to potential advances in quantum computing, Sigman noted.  

According to Bitcoin Libre’s CEO, using hashes instead of public keys would eliminate the risk of exposing sensitive information, as hashes are results of one-way functions that cannot be reversed to obtain the original input, even “with advanced technology.” 

BIP-360 includes support for multi-signature

Continuing his explanation, Sigman explained that P2QRH introduces the ability to use multiple types of keys in a transaction. This means that a user could employ both traditional keys (ECDSA) and keys resistant to quantum computing. 

This mixed approach would allow users to gradually transition to technologies that would be more secure while maintaining compatibility with the current system. 

For example, a user could set up a multi-signature wallet that requires both a traditional key and a quantum-resistant key to authorize transactions. This would benefit security, and encourage more flexible adoption. 

In addition, P2QRH’s design leaves room for incorporating advanced cryptographic primitives. This means that if even more powerful quantum algorithms or new advances in quantum-resistant cryptography emerge in the future, Bitcoin could adapt without the need to introduce new disruptive mechanisms. 

BIP-360 would not increase block space in Bitcoin

As for the efficiency of P2QRH, Sigman argued that it is “designed to minimize block size growth, optimizing quantum-resistant signatures.” 

Compared to ECDSA, quantum-resistant signatures are typically larger, which could increase the load on the network. P2QRH would propose optimizations to minimize this impact, keeping transactions compact and decreasing the on-chain data size. 

Sigman went on to say that P2QRH follows a similar approach to SegWit. BIP-360 separates out the additional data required for quantum resistance, ensuring that older nodes can verify transactions without having to process all the new information. This would enable a reduction in computational cost for older nodes and facilitate gradual adoption. 

The implementation would be done through a soft fork, meaning that non-upgraded nodes will continue to operate on the network, even if they do not take advantage of the new features of P2QRH. This feature is important to avoid network fragmentation and ensure a smooth transition.

In this way, BIP-360 seeks to shield Bitcoin from potential future risks of quantum computing, offering a transition towards post-quantum cryptography that ensures integrity and trust in the network.   

However, it is worth remembering that, according to many analysts, the risk of quantum over Bitcoin is still far away.