The Q-Day Prize challenge, explained: Can quantum computers really break Bitcoin?

What is the Q-Day prize?

The Q-Day Prize is simply a situation to marque the Bitcoin web quantum resistant.

On April 16, 2025, quantum computing-focused institution Project 11 announced the “Q-Day Prize,” a contention to interruption a “toy version” of Bitcoin’s cryptography with a quantum computer. Contestants indispensable implicit the Q-Day Prize challenge by April 5, 2026.

Their reward? 1 Bitcoin (BTC).

The “Q” successful Q-Day refers to quantum computing, the imaginable menace to galore existing cryptographic information measures. 

But tin quantum computers interruption Bitcoin? Let’s find out.

Quantum computing and the menace to Bitcoin

Bitcoin utilizes the SHA-256 hashing algorithm, a National Security Agency (NSA)-developed encryption algorithm. SHA-256 prevents brute force attacks against the Bitcoin network, arsenic decrypting it with existent hardware tin instrumentality decades. However, the emerging menace to SHA-256 is quantum computing, a method of computing that harnesses quantum physics and is overmuch faster than accepted computing.

At a cardinal level, quantum computing utilizes quantum bits (qubits), which tin beryllium successful aggregate states. This contradicts binary (traditional) computing, which uses binary bits (1s and 0s). In 1994, mathematician Peter Shor presented an algorithm for quantum computers to lick analyzable algorithms successful seconds, alternatively than the decades it tin instrumentality for accepted hardware. At the time, nary hardware could efficaciously tally it, but recent advances similar Google Willow are nearing that capability.

Quantum computing, erstwhile paired with Shor’s algorithm, tin disrupt Bitcoin cryptographic systems arsenic we cognize them. Shor’s algorithm allows quantum computers to lick analyzable mathematics ace fast, perchance threatening Bitcoin’s safety.

Did you know? If quantum tech gets beardown enough, Bitcoin’s existent information could go obsolete, truthful developers are racing to make “quantum-proof” shields utilizing caller mathematics that adjacent Shor’s algorithm can’t break.

Quantum menace to Bitcoin: How existent is the danger?

Bitcoin is susceptible to quantum computing, but however superior is the risk?

When you make a crypto wallet, it generates 2 important things: a private cardinal and a nationalist key. The backstage cardinal is simply a concealed code, similar a password, that you indispensable support safe. The nationalist cardinal is created from your backstage key, and your wallet code (like a slope relationship number) is made from the nationalist key.

You stock your wallet code with others truthful they tin nonstop you cryptocurrency, conscionable similar you stock your email code for idiosyncratic to interaction you. However, you ne'er stock your backstage key. It’s similar the password to your email — lone you request it to entree and walk the wealth successful your wallet.

Your private key is similar a maestro password that controls your crypto wallet. From this backstage key, your wallet tin make galore nationalist keys, and each nationalist cardinal generates a wallet address. 

For example, if you usage a hardware wallet, it has 1 backstage cardinal but tin make unlimited nationalist keys (wallet addresses). This means you tin person antithetic addresses for each cryptocurrency supported by the wallet oregon adjacent aggregate addresses for the aforesaid cryptocurrency, each managed by a azygous backstage key.

While generating a nationalist cardinal from a backstage cardinal is straightforward, figuring retired a backstage cardinal from a nationalist cardinal is highly hard — astir intolerable — which keeps your wallet secure. Every clip you nonstop cryptocurrency, your backstage cardinal creates a peculiar codification called a signature. This signature proves you ain the funds and privation to nonstop them. The strategy that uses your backstage key, nationalist cardinal and signature to unafraid transactions is called the Elliptic Curve Digital Signature Algorithm (ECDSA).

It is believed that quantum computing could reverse the process and make backstage keys retired of nationalist ones. It is feared that this could origin galore Bitcoin holders (especially whales and Satoshi-era wallets) to suffer their funds. 

Bitcoin code types and quantum risks

When you nonstop Bitcoin, you usage a circumstantial code benignant to nonstop the payment. Each code benignant has unsocial features, affecting security, privateness and vulnerability to quantum computing attacks similar Shor’s algorithm.

P2PK code types

When you wage idiosyncratic with Bitcoin, the transaction is typically considered a “pay-to-public-key” (P2PK). This was the astir communal outgo method successful 2009, according to a report from consulting steadfast Deloitte. 

Much of the archetypal Bitcoin released astatine the network’s motorboat is held successful wallets with the P2PK code type, chiefly owed to the information that they’ve sent transactions since Bitcoin’s 2009 launch. These addresses are agelong (up to 130 characters), making them little user-friendly.

Wallets with the P2PK code benignant are astir susceptible to Shor’s algorithm, arsenic it tin brute unit the backstage cardinal from a P2PK wallet address. 

P2PKH code types

There’s a 2nd code benignant that’s much resistant to Shor’s algorithm: the pay-to-public-key-hash (P2PKH). P2PKH addresses are shorter and are generated from the hash (a unique, hexadecimal value) of a nationalist cardinal created utilizing SHA-256 and RIPEMD-160 algorithms alternatively of displaying the afloat cardinal itself.

These addresses are shorter (33-34 characters), commencement with “1,” and are encoded successful Base58 format. Such addresses are wide utilized and see a checksum to forestall typos, making them much reliable.

P2PKH addresses are much resistant to Shor’s algorithm than P2PK due to the fact that the nationalist cardinal is hashed. The nationalist cardinal is lone revealed erstwhile you walk from the code (not erstwhile receiving). If a P2PKH code ne'er sends Bitcoin, its nationalist cardinal stays hidden, offering amended extortion against quantum attacks. 

However, reusing a P2PKH code (sending from it aggregate times) exposes the nationalist key, expanding vulnerability. Also, erstwhile you walk from a P2PKH address, the nationalist cardinal becomes disposable connected the blockchain, making transactions trackable.

Taproot addresses

Taproot is the newest code type, introduced successful November 2021 via the Taproot brushed fork. It uses Schnorr signatures alternatively of the ECDSA signatures utilized by P2PK and P2PKH. These addresses commencement with “bc1p,” usage Bech32m encoding, and are 62 characters long.

They connection amended privacy. Multisignature (multisig) transactions look similar single-signature ones, hiding analyzable spending conditions. However, Taproot addresses exposure the nationalist cardinal (or a tweaked version), making them susceptible to Shor’s algorithm, akin to P2PK. 

Did you know? Google’s “Willow” computer chip is susceptible of solving a analyzable occupation successful conscionable 5 minutes. The aforesaid task would instrumentality a classical supercomputer 10 septillion (!) years.

The contention toward quantum-proofing Bitcoin

Quantum absorption is simply a existent challenge, but not an intolerable one.

Quantum computers, inactive successful aboriginal development, could 1 time usage Shor’s algorithm to interruption Bitcoin’s cryptography by deriving backstage keys from nationalist keys. This would endanger Bitcoin and different systems utilizing SHA-256 oregon ECDSA (the algorithms securing Bitcoin transactions). However, this menace is not imminent, and solutions are already successful progress.

While immoderate judge that Project 11 presented the Q-Day Prize to instrumentality down Bitcoin, the institution claims this inaugural is aimed astatine “quantum-proofing” the network.

In July 2022, the US Department of Commerce’s National Institute of Standards and Technology (NIST) announced 4 quantum-resistant cryptographic algorithms resulting from a six-year situation to make specified solutions.

Quantum computing won’t make successful isolation, and centralized systems similar authorities and fiscal networks could beryllium bigger targets than Bitcoin’s decentralized blockchain. These systems usage outdated cryptography, similar RSA, susceptible to Shor’s algorithm, and store delicate information (e.g., banking records). Their azygous points of nonaccomplishment marque breaches easier than attacking Bitcoin’s distributed nodes. 

The International Monetary Fund warns quantum computers could disrupt mobile banking, portion Dr. Michele Mosca from the Institute for Quantum Computing highlights “harvest-now, decrypt-later” risks for centralized information (where attackers store encrypted information contiguous to decrypt with aboriginal quantum computers). In 2024, the G7 Cyber Expert Group urged fiscal institutions to assess quantum risks, noting that centralized systems’ information could beryllium exposed if intercepted present and decrypted later.

Did you know? Many blockchain networks are exploring quantum-resistant algorithms, specified arsenic Quantum Resistant Ledger oregon Algorand. These quantum computing blockchain information methods contiguous a fewer antithetic approaches.

How to summation your information against quantum threats

While the quantum computing cryptocurrency hazard is little of a menace than 1 mightiness think, it’s inactive champion to enactment prepared.

Still, if you’re disquieted astir Bitcoin quantum vulnerability, determination are a fewer precautions you tin instrumentality to unafraid your crypto finances.

• Avoid reusing nationalist addresses: Most crypto wallets let you to make a caller nationalist code for each transaction. This signifier volition marque it overmuch harder to way your spending habits.
• Move funds to a backstage wallet: If you’ve been utilizing the aforesaid nationalist wallet code for immoderate time, see moving your funds to a caller wallet with nary history. This volition assistance support your spending habits private. 
• Use a antithetic blockchain network: Legacy networks similar Bitcoin and Ethereum are considered little quantum resistant than newer networks with much modern information algorithms. Consider alternate networks with quantum absorption successful mind.
• Stay informed: Pay attraction to the results of the Q-Day Prize challenge, and enactment up to day with quantum computing quality truthful you tin respond accordingly. The champion defence is an informed one.

While quantum hazard is not immediate, developers and cybersecurity experts are actively moving connected solutions to guarantee semipermanent security. In the meantime, users should enactment updated astir Bitcoin protocol updates and champion practices, specified arsenic avoiding code reuse, arsenic the web gradually moves toward quantum resistance.