Monero Considers Detective Mining and Consensus Changes After 51 Percent Attack

Monero Community Considers Consensus Changes After 51% Attack

The Monero (XMR) community is currently evaluating significant changes to its Proof-of-Work (PoW) consensus mechanism following a 51% attack. According to Cointelegraph: Bitcoin & Krypto-Nachrichten, several proposals are under discussion, including localizing mining hardware, switching to a merge-mining algorithm, enabling XMR mining alongside Bitcoin (BTC) or other major cryptocurrencies, and implementing Dash’s ChainLocks solution.

The ChainLocks method, as used by Dash, employs randomly selected masternodes to form a quorum for the first valid block broadcasted to the network. This process temporarily locks the blockchain ledger, allowing only blocks verified by the ChainLock system to be added. This would work in tandem with the existing PoW consensus. Joel Valenzuela, a developer at Dash DAO, explained that ChainLocks can prevent 51% network attacks and block reorganizations, even if malicious miners control a higher cumulative PoW than the ChainLocks-verified chain. However, Valenzuela also cautioned that blockchains using ASICs must ensure their economic models are robust to avoid attacks.

Qubic, a blockchain and mining pool specializing in AI, announced in August that it had gained 51% control over Monero, raising concerns that other PoW blockchains could also be targeted. Qubic currently controls 2.18 gigahashes per second (GH/s), making it the largest Monero mining pool, according to MiningPoolStats. The second-largest pool, Supportxmr, has a hash rate of 1.18 GH/s.

The Monero community remains divided over the incident. Some users claim Qubic never actually controlled the majority of the network’s hash power and only performed a limited block reorganization, not a full network takeover. Despite these claims, the Kraken exchange temporarily suspended Monero deposits, later reinstating them with a requirement of 720 confirmations before XMR is credited to accounts. Kraken stated, “Given the current uncertainty regarding the security of the Monero network due to significant consolidation of hash power under a single entity, Kraken may suspend deposits at any time and delay crediting at its discretion.”

Additionally, the Qubic community voted to make Dogecoin (DOGE) their next mining target, with over 300 votes—more than all other options combined. Sergey Ivancheglo, founder of the Qubic network, clarified that mining DOGE would require months of development and that the pool is currently focused on XMR.

• Monero is considering multiple technical solutions to prevent future 51% attacks.
• Qubic’s dominance in hash rate has led to immediate reactions from exchanges like Kraken.
• The community is split on whether a true 51% attack occurred.

“Given the current uncertainty regarding the security of the Monero network due to significant consolidation of hash power under a single entity, Kraken may suspend deposits at any time and delay crediting at its discretion.” – Kraken, as reported by Cointelegraph

Key Takeaway: The Monero network is under pressure to enhance its security mechanisms after a major mining pool demonstrated control over more than half of the network’s hash rate, prompting both technical and operational responses from the community and exchanges.

Monero Responds to Hashrate Shock – Developers Consider “Detective Mining” as a Defense Strategy

On August 12, the Qubic mining pool claimed to have temporarily controlled more than 51% of Monero’s network hashrate, triggering a reorganization of six blocks. Qubic described this as a “51%-takeover demo” and openly discussed the use of selfish mining—a tactic where a miner or pool withholds its own blocks to later release them for outsized rewards. This event served as a warning for exchanges, with Kraken halting XMR deposits due to concerns over excessive hashrate concentration and network security. Although trading and withdrawals remained open, the incident highlighted how even a twelve-minute reorganization (Monero has 2-minute blocks) can undermine trust in central infrastructure.

However, not everyone agrees with Qubic’s interpretation. Researchers from the RIAT Institute argued that the measured hashrate was significantly lower and that a six-block reorganization does not prove long-term network control or the ability to reverse confirmed transactions.

In response, former Monero maintainer Riccardo “fluffypony” Spagni proposed “Detective Mining” as a defense. This is not a protocol change but a strategy for mining pools. Each pool would publish job messages via Stratum protocols, including the previous block hash (prevhash). Detective miners or proxy systems could monitor these streams, and if a prevhash does not match the public blockchain, they would immediately build and publish a valid block on the “hidden” parent block. This forces selfish miners to reveal their private chain or lose their advantage. The key advantage is that this defense can be integrated into existing pool software without a hard fork or consensus change.

Spagni referenced the Lee–Kim model (2019), which shows that Detective Mining significantly increases the cost of selfish mining. If about half the hashrate (i.e., the largest pools) activate Detective Mining, the profitability threshold for selfish mining rises from around 25–33% to 32–42% hashrate, depending on assumptions. The more pools participate, the less attractive attacks become.

The proposal also addresses potential countermeasures, such as quorum detection with multiple sensors, short grace periods before redirecting hashrate, share submission checks to filter out fake jobs, and rate limits with telemetry to reduce false positives. The approach is positioned as a practical playbook for pools rather than a deep protocol change, aligning with Monero’s philosophy of strengthening incentives and operations before altering consensus mechanisms.

Whether Detective Mining will be implemented depends largely on the coordination of major pools. Only if a critical mass adopts the defense mechanisms will attack costs rise to the predicted level. The idea remains under public discussion in the Monero Research Lab, but the Qubic incident has made the risks clear and increased the urgency for a deployable, non-hard-fork solution.

1. Qubic’s temporary control of over 51% of Monero’s hashrate led to a six-block reorganization.
2. Kraken suspended XMR deposits, citing network security concerns.
3. Detective Mining could raise the profitability threshold for selfish mining attacks to 32–42% hashrate.
4. The solution requires no protocol changes and can be implemented at the pool level.

“Detective Mining raises the bar for profitable selfish mining attacks without requiring protocol changes, making attacks less attractive as more pools participate.” – Riccardo “fluffypony” Spagni, as reported by coin-update.de

Key Takeaway: The Monero community is actively exploring Detective Mining as a practical, immediately deployable defense against selfish mining and 51% attacks, with the effectiveness hinging on broad adoption among major mining pools.

Sources:

• Monero-Community überdenkt Konsensverfahren nach 51-Prozent-Attacke
• Monero reagiert auf Hashrate-Schock – Entwickler prüfen „Detective Mining“ als Abwehrstrategie