Bitcoin Magazine: Could Quantum Computing Pose a Risk to Bitcoin Security?
(BitcoinMagazine) ITQ-News has summarized here the Bitcoin Magazine article discussing quantum computing’s potential risk to bitcoin. Click on source for extensive discussion of potential quantum computing attacks on bitcoin and also methods for combating potential quantum attacks.
Theoretical methods of attacking bitcoin with quantum computing:
1 Transaction hijacking: Here, an attacker computes the private key from a public key of a pending transaction and creates a conflicting transaction spending the same coins, thus stealing the victim’s assets. Timing is crucial for such attacks. Hence, the performance level of quantum computers dictates the success probability of this threat vector.
2 Selfish mining: In this potential attack vector, the attacker could theoretically use Grover’s algorithm to gain an unfair advantage when mining. The ability to mine quickly in a sudden quantum speedup could lead to destabilization of prices and control of the chain itself, resulting in possible 51% attacks.
Combined attacks: Combining the above two vectors, an attacker could theoretically build up a secret chain and, when in the lead, selectively publish blocks to reorganize the public chain.
Methods for combating potential quantum attack vectors
1 Data gathered via mempool APIs can be used to run real-time machine learning algorithms to spot anomalies in offered transaction fees and thus, flag attempts at transaction hijacking.
2 A “reputation score” can be computed for each node in the blockchain. APIs capturing device details, IP address, etc. can be used to cluster activities (mining and/or transactions) into homogenous clusters, thus having a high chance of originating from the same users. Such patterns can also be used to directly detect quantum computers in the blockchain. ‘’Reputation scores’’ might be of special significance in case of combined attacks
Wallet interface design
1 Intelligent design of user interface can help in alerting customers to the risk of reusing addresses, via strategic placement of warning messages.
2 Principles of effective incentive design can be used to formulate changes in consensus rules, such as applying a markup on transaction fees for p2pk and reused p2pkh wallets. This would prompt users to switch to safer behavior.