Other signature schemes could replace the Elliptic Curve Digital Signature Algorithm.
The replacement would seek to prevent the derivation of private keys from public bitcoin addresses.
The community of users and developers have expressed their concern about the future of Bitcoin in the face of the advent of quantum computing. To date, concerns have mainly focused on the SHA-256 algorithm, a cryptographic function that regulates the mining of the crypto asset and converts any block of data into a fixed-length character string. This hash function serves to, through proof of work, preserve the integrity of the protocol, specifically the authenticity of the blocks and the legitimacy of transactions on the network. It also helps verify transactions, avoiding double spending events.
However, there is a second line of defense for Bitcoin against quantum, focused not on the protection of the BTC accounting record, its distribution and integrity; but of the signing of transactions with the currency and the guarantee of exclusive possession over them through private keys securely encrypted.
According to this line of development, wallets would need to adopt (what is not yet known how urgently) signature algorithms resistant to quantum attacks, and be able to preserve the privacy and security of users who use bitcoin.
How do bitcoin wallets work today?
Today, Bitcoin wallets incorporate the scheme called Elliptic Curve Digital Signature Algorithm (ECDSA) to generate digital signatures capable of validating transactions on the network.
According to bitcoin.it, a source of technical information on the crypto asset, this signature algorithm used by the wallets depends on the hash function used by Bitcoin (SHA-256), but is not identical to it.
To achieve wallet protection, These require an algorithm that encrypts the generation and use of the user’s keys.. The same page that documents Bitcoin comments: “ECDSA’s signature and verification algorithms use some fundamental variables that are used to obtain a signature and the reverse process of obtaining a message from a signature.”
The computational power of today’s computers means that the ECDSA is sufficient for now to ensure that the funds in a bitcoin address can only be spent by its rightful owner(s), and that the relationship between public and private signatures cannot be easily decrypted.
However, the ability of quantum computer algorithms to factor numbers and solve mathematical problems could make this algorithm obsolete at some point, which would have implications.
For example, data leaks with user passwords that would facilitate access to private wallets and the theft of funds. In other words, a massive theft of bitcoin and cryptocurrencies during the social climax of quantum technology, when people capable of efficiently handling it have access to it at the same time.
Given this latent danger, what can be done to protect bitcoin wallets?
Cryptographers, even pre-bitcoiners, have been thinking about possible solutions for post-quantum cryptography for years. This is because the quantum concern is not new, and it affects technological society as a whole.
In 1994, Peter Shor demonstrated how quantum computers were “able to break all the digital signature schemes that are used today.”
A group of technicians and developers asked themselves, as a result of the previous demonstrations, the following: what type of digital signature algorithms are still secure in the era of quantum computers?
According to Buchman, “there are several candidates for post-quantum signature schemes. The most efficient are NTRU, SFLASH and the Merkle scheme”.
NTRU It is an encryption system that uses polynomials (types of mathematical equations) to protect sensitive information. One of its advantages is that it is fast and requires little memory, making it efficient and resistant to quantum computer attacks.
SFLASH is a symmetric key cryptographic scheme designed to be efficient on resource-constrained devices.
SFLASH is designed to be a very fast signature system, both for signature generation and verification. It’s much faster than RSA at signing and much easier to implement on smart cards without any arithmetic coprocessor, for example.
Courtois, Goubin and Patarin, technical paper on SFLASH.
The Merkle scheme, for its part, is one whose “security is based on the absence of collisions between an arbitrary cryptographic hash function and an arbitrary single signature algorithm.” According to the paper by Buchman and company, the Merkle scheme has competitive efficiency, and as CriptoNoticias reported, progress has been made in the application of this scheme to Bitcoin cryptography using the OP_CAT operation code. Bitcoin uses the Merkle scheme since its origins.
However, the introduction of OP_CAT and a quantum-proof Merkle scheme would help improve verification processes in the Bitcoin protocol.
The solution to achieve more secure post-quantum bitcoin wallets would then be in integrate robust signature schemes with greater processing powerwhich may come in the future. These new schemes would enhance the Elliptic Curve Digital Signature Algorithm (ECDSA) or replace it entirely.
Developers can find a way to use these signature models with Bitcoin wallets, positively affecting the security and the way they generate keys to avoid guessing the private key from the public key, or the so-called “problem of discrete elliptic logarithm.
