Quantum Computers Pose New Threats to Bitcoin's Encryption

Quantum computers have long been touted as potential game-changers in the field of cryptography. But how exactly do they pose a threat to secure digital transactions? To understand this, let's take a closer look at bitcoin's encryption and the weaknesses it has.

Bitcoin uses elliptic curve cryptography, which involves generating public keys from private ones using a mathematical operation called 'secp256k1.' This creates a one-way trapdoor: it's easy to go forward but difficult to reverse-engineer the process. However, Shor's algorithm, discovered in 1994 by Peter Shor, has been known to break this trapdoor efficiently.

Shor's algorithm relies on three key quantum properties: superposition, entanglement, and interference. By harnessing these properties, it can solve the discrete logarithm problem in polynomial time, rendering bitcoin's encryption vulnerable. But what does this mean in practical terms?

The study by Google's Quantum AI division has introduced a new attack scenario that takes advantage of precomputed parts of Shor's algorithm and exposed public keys on the blockchain. This 'at-rest' attack can take place over an extended period, putting 6.9 million bitcoins at risk. Moreover, if a user broadcasts a transaction and their public key is visible in the mempool, a quantum attacker has roughly nine minutes to derive a private key and submit a competing transaction.