After this article, you will no longer be fooled by scare tactics and exaggerated fears of quantum computing threatening Bitcoin, with an in-depth and comprehensive technical explanation

By Eli Nagar - CEO of Braiins Translated with some adaptation
April 11, 2026

I wrote this article because I wanted to understand the topic better myself. It then turned into a comprehensive technical report on how quantum computers could break Bitcoin, what proposed solutions exist, and how a new scheme called QSB works without requiring any upgrades to the Bitcoin protocol network.

Section 01: The cryptographic foundations of Bitcoin:
Before diving into the quantum threat, I realized I first needed to understand how Bitcoin actually works under the surface. Bitcoin relies on several mathematical tools to keep your satoshis and bitcoins secure. Let’s go through each one.
- Public keys, private keys, and addresses:
*Private key (PRIVATE KEY):
A secret number generated randomly. Think of it as your Bitcoin wallet’s password. It’s a 256-bit number, chosen from a set of about 10⁷⁷ possibilities (more than the number of atoms in the observable universe). If someone knows your private key, they can steal your bitcoins.
*Public key (PUBLIC KEY):
A number mathematically derived from the private key using a one-way function called elliptic curve multiplication (remember this). You can share your public key freely; no one can reverse-engineer the private key from it — at least not with today’s hardware. Bitcoin uses a specific elliptic curve called secp256k1.
*Bitcoin address (BITCOIN ADDRESS):
A shortened, hashed version of the public key. When someone sends you Bitcoin, they send it to your address. Importantly: the address hides the actual public key behind two layers of hashing (SHA-256 + RIPEMD-160), adding an extra layer of security.
*How transactions are signed:
When you send Bitcoin, you create a transaction and must prove you own the coins. You do this by producing a digital signature using the ECDSA algorithm.

* ECDSA (Elliptic Curve Digital Signature Algorithm): — A mathematical procedure that takes your private key and transaction data, producing a signature. Anyone can verify this signature using your public key, but no one can forge it without the private key. Bitcoin uses ECDSA with the specific curve secp256k1.
*Digital signature: — A pair of numbers (called r and s) that mathematically prove: "The person who owns the corresponding private key authorizes this specific transaction." Any change in the transaction (even one byte) invalidates the signature.
*How mining uses SHA-256
SHA-256 :(Secure Hash Algorithm, 256-bit) — A hashing function. A mathematical grind. You input any data (a word, a file, a whole book) and it produces a fixed-size 256-bit "fingerprint." The same input always yields the same output, but even a tiny change in the input produces a completely different output. Most importantly: you cannot reverse the process to find the input from the output.
Bitcoin miners repeatedly hash block data with SHA-256, trying trillions of variations per second to find one that begins with a certain number of zeros. This is the "proof of work" that secures the network. The more zeros required, the harder the puzzle.

-Section 02: The quantum computer threat:
Here’s where things start to get interesting for me. Classical computers store information as bits (bits). Each bit is either 0 or 1. But quantum computers use qubits (qubits), which can exist in a "superposition" (superposition) of 0 and 1 simultaneously. This property, along with entanglement (entanglement) — where qubits are linked in ways that classical bits cannot be — allows quantum computers to solve certain types of mathematical problems exponentially faster than any classical computer.
When you measure a qubit, the superposition collapses, and you get either 0 or 1. But before measurement, quantum algorithms can process all possible states at once.
One thing I kept encountering in my research: quantum computers are not "faster computers" in general. They are specialized tools that exploit quantum physics for specific types of problems. Unfortunately, two of those problems are directly related to Bitcoin.

*Shor’s algorithm: the key cracker:
Shor’s algorithm — discovered by mathematician Peter Shor in 1994 — can solve the discrete logarithm problem and integer factorization efficiently on a quantum computer. These two mathematical problems underpin most modern cryptography, including Bitcoin’s ECDSA signatures. On a classical computer, these problems would take billions of years. On a large enough quantum computer, they could be solved in hours.$BTC