Key Points - Bitcoin's encryption is theoretically crackable with a powerful enough quantum computer. - Those computers don't exist yet, but they might within a decade or less. - The main obstacles to mitigating the threat are social and organizational in nature, not technological. On July 21, asset manager Galaxy Digital pledged to spend up to $5 million to defend Bitcoin(CRYPTO: BTC) against a future quantum computer that could crack the cryptography guarding everyone's coins. No such computer exists yet, and there probably won't be one for at least five years at the earliest. Even so, the quantum threat to Bitcoin already appears as a disclosure in the risk filings of BlackRock's iShares Bitcoin ETF. So is the quantum threat to Bitcoin real, or is it an academic issue that's become overblown? Missed Nvidia in 2009? This Rare Signal Is Flashing Again.In 2009, a "Double Down" signal flashed for a little-known chipmaker called Nvidia. For the first time in years, that same "Total Conviction" signal is flashing for a company 1/100th the size of Nvidia. Continue » What could a quantum computer actually do to this coin? Bitcoin's mining and ledger are built on SHA-256, a hash function that quantum computers cannot efficiently break. That means nobody, not even someone with a sufficiently powerful quantum computer, will be able to mine all of the as-yet unmined coins all at once, nor will they be able to change the details of the past transactions on the chain. The weak spot is its system of digital signatures, known as the elliptic curve digital signature algorithm (ECDSA), which is used to prove ownership whenever coins are spent. A powerful enough quantum computer could work backward from a wallet's public details to recover the private key that controls it and then drain the coins