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Bitcoin Draft to Sunset Legacy Signatures for Quantum Risk Faces Pushback

Opponents tout opt‑in defenses, including a bounty 'canary' that activates only after a proven attack.

Overview

  • BIP-361, updated Tuesday in Bitcoin’s proposal repository and built on BIP-360’s quantum-safe output type, remains a draft that would block deposits to legacy addresses after about three years and then invalidate old signatures after five, with a research-only recovery option using zero-knowledge proofs.
  • Roughly one third of all bitcoin, estimated at 6.7 to 6.9 million BTC, has exposed public keys on-chain, including Satoshi-era holdings around 1.1 to 1.7 million coins that would be prime targets for a future quantum attacker.
  • BitMEX Research proposed a “canary” system that posts a bounty to a special address and triggers restrictions only if a quantum-capable party spends from it, creating public proof of the threat before any network‑wide freeze.
  • Blockstream CEO Adam Back, speaking Wednesday at Paris Blockchain Week, urged optional, opt‑in quantum‑resistant upgrades and said the community can coordinate quickly in a crisis without preset freezes.
  • Cardano founder Charles Hoskinson said the plan would require a hard fork and argued that about 1.7 million pre‑2013 coins lack seed phrases needed for the proposal’s zero‑knowledge recovery.