How Does Monero Work?
Monero is the leading privacy-focused cryptocurrency, using mandatory ring signatures, stealth addresses, and RingCT to make all transactions private by default. With a market cap of approximately $6.3 billion, XMR ranks among the top 20 cryptocurrencies. Its C+ grade reflects significant recent security events — Qubic mining pool executed 51% attacks with 6-block and 18-block chain reorganizations in August-September 2025 — combined with 73 exchange delistings in 2025 due to regulatory pressure on privacy coins. These risks are balanced by 10+ years of operation, a fair-launch distribution, and a tail emission model providing permanent mining incentives.
TVL
—
Sector
L1
Risk Grade
C
Value Grade
B-
Core Mechanisms
5.1.1
RandomX Proof-of-Work — CPU-optimized, ASIC-resistant mining algorithm designed for commodity hardware
RandomX launched in November 2019 to maintain ASIC resistance. CPU-friendly design enables broader participation but also makes hashrate rentable via general-purpose compute.
1.1.4
Monero tail emission — perpetual 0.6 XMR per block after initial supply exhaustion (reached June 2022)
Tail emission provides a permanent security budget. Annual inflation ~0.86% and declining. Novel at introduction but now an established pattern in the taxonomy.
4.3.1
Ring signatures with RingCT — mandatory transaction privacy using ring signatures to obscure sender among decoy outputs
CryptoNote ring signatures in production since 2014. RingCT added in 2017 to hide amounts. Ring size currently set to 16.
4.3.1
Stealth addresses — one-time addresses generated per transaction to protect recipient privacy
Standard CryptoNote feature. Each transaction creates a unique destination address, preventing address linking.
1.3.1
Dynamic block size with penalty-based fee mechanism — blocks can grow beyond median size with a quadratic miner reward penalty
Adaptive block size allows throughput scaling without hard forks. Penalty prevents spam while allowing organic growth.
5.2.1
Monero difficulty adjustment — recalculates every block using a moving average for smooth adjustments
Per-block adjustment is more responsive than Bitcoin's 2,016-block window, reducing vulnerability to hashrate oscillation.
How the Pieces Interact
The August-September 2025 Qubic 51% attack demonstrated that RandomX's CPU-friendly design makes hashrate capturable through dual-mining incentives. A successful chain reorganization on a privacy chain is particularly dangerous because it can enable double-spend attacks that are harder to detect and trace than on transparent chains.
Mandatory privacy for all transactions means the entire supply is unauditable from the blockchain alone. If a cryptographic flaw in ring signatures or RingCT allows undetectable token creation, there is no transparent pool to cross-reference. Supply integrity depends entirely on the soundness of multiple privacy primitives working in concert.
While tail emission provides a permanent mining incentive (0.6 XMR/block), the relatively low emission rate may not generate sufficient miner revenue at lower XMR prices to prevent hashrate concentration. The 2025 attacks occurred despite active tail emission, suggesting the incentive may be insufficient to maintain decentralized mining.
Private transactions are larger than transparent transactions due to ring signatures and RingCT proofs. The dynamic block size accommodates growth, but larger transactions mean higher per-transaction resource costs, limiting throughput compared to transparent chains.
73 exchange delistings in 2025 demonstrate that mandatory privacy directly conflicts with regulatory compliance requirements. As atomic swaps and DEX access grow, Monero's economy increasingly depends on decentralized infrastructure that is less liquid and less accessible than centralized exchanges.
What Could Go Wrong
- In August-September 2025, the Qubic mining pool gained >51% of Monero's RandomX hashrate through its 'useful Proof-of-Work' dual-mining incentive, executing a 6-block reorganization in August and an 18-block reorganization in September. Kraken halted XMR deposits during the incidents. This demonstrated that Monero's RandomX mining can be captured by a single well-incentivized pool.
- Monero faced 73 exchange delistings in 2025, including restrictions from Binance and Kraken across parts of Europe, severely fragmenting centralized exchange liquidity. Mandatory privacy features make Monero a primary target for regulatory action, and atomic swap adoption is growing as an alternative access mechanism.
- Mandatory privacy (ring signatures, stealth addresses, RingCT) means all transactions are private by default, making supply auditability dependent on the cryptographic soundness of the privacy primitives. Unlike Zcash's opt-in privacy, there is no transparent fallback to verify total supply.
- The community is exploring defensive measures including ChainLocks integration, merge mining with Bitcoin, and the 'Publish or Perish' proposal, but these are not yet implemented, leaving the network vulnerable to repeat hashrate concentration attacks.
Repeated Hashrate Capture Enabling Systematic Double-Spend
ElevatedTrigger: A mining pool or dual-mining scheme (similar to Qubic's uPoW model) captures >51% of RandomX hashrate for periods exceeding 24 hours, enabling reorganizations deeper than the 10-block safety threshold.
- 1.A dual-mining incentive (like Qubic's uPoW) attracts >51% of Monero's RandomX hashrate to a single pool — The pool gains ability to produce blocks faster than the rest of the network and perform chain reorganizations
- 2.Attacker executes deep reorganizations (18+ blocks as demonstrated in September 2025) to reverse confirmed transactions — Double-spend attacks succeed against exchanges and merchants. Due to mandatory privacy, the double-spend is harder to trace and prove than on transparent chains
- 3.Remaining exchanges with XMR listings increase confirmation requirements to 100+ blocks or suspend deposits entirely — Effective settlement time increases from ~20 minutes to hours, destroying XMR's utility for commerce and exchange transfers
- 4.Network confidence collapses, XMR price declines, further reducing mining revenue and honest hashrate — Negative spiral where reduced price makes the attack cheaper relative to declining miner revenue, enabling persistent hashrate control
Risk Profile at a Glance
Overall: C (43/100)
Lower score = safer