Is Monero Quantum Safe?

Monero faces a uniquely devastating quantum threat. While most cryptocurrencies risk financial theft, Monero risks retroactive destruction of all privacy. Ring signatures, stealth addresses, and Pedersen commitments all rely on the discrete logarithm assumption. When quantum computers break this, every historical Monero transaction becomes deanonymizable — revealing senders, receivers, and amounts for the entire blockchain history.

Monero's privacy model creates layers of quantum vulnerability. Ring signatures obscure the true signer by including decoy inputs — but the ring signature construction relies on ECDLP, which Shor's solves. A quantum computer could identify the real signer in every ring, deanonymizing all historical transactions. Stealth addresses (one-time addresses generated via Diffie-Hellman) could be linked to recipients. Pedersen commitments hiding transaction amounts could be opened. Bulletproof range proofs — which prove amounts are positive without revealing them — would also fail. The devastating aspect is retroactivity: all historical Monero transactions are recorded on-chain with encrypted privacy. Quantum computers could decrypt the entire history at once, retroactively exposing years of "private" transactions.