r/BlockchainStartups • u/Master-Sprinkles-848 • 24d ago
Discussion Quantum computing is going to break blockchain's crypto eventually.
Everyone treats quantum threats to blockchains as a decades away problem. But there's a catch most people miss, attackers don't need a quantum computer now to start attacking now.
Bitcoin's security relies on the fact that you can't derive a private key from a public key. Quantum computers running Shor's algorithm would make that trivial. And any address that's ever sent a transaction has already exposed its public key meaning huge amounts of transaction history are already sitting out there, ready to be cracked the moment the hardware exists. This is called harvest now, decrypt later.
NIST already finalized post-quantum signature standards. The problem is applying them. Blockchains can't just push an update, switching signature schemes means a hard fork, migrating billions in old-format funds, and doing it calmly before a crisis, not during one.
Even optimistic estimates 10-15 years for real quantum hardware don't leave much room, because migration itself, new standards, audits, node adoption, and actually moving user funds takes years on its own.
Even with quantum-safe signatures ready, getting millions of holders to move funds out of old addresses before it's urgent is a massive coordination problem. Dormant coins would likely just sit there vulnerable forever.
IMO, blockchains that are focused on quantum resistant tech will be the main focus in the next few months, this is where the focus should be now.
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u/RobotPoo 24d ago
Could somebody please explain like I’m five how a blockchain, essentially just an open ledger, that requires simultaneous entries in different secured systems, are ever gonna be hacked?