[Coinbase Claims to Custody Approximately 5% of Bitcoin, Urges Immediate Action for Quantum Migration] Odaily Planet Daily News: Cryptocurrency exchange Coinbase stated that it holds custody of approximately 5% of the total existing Bitcoin and urged Bitcoin developers to immediately address the threat posed by quantum computing. Coinbase pointed out that changes to Bitcoin consensus and ecosystem migration could take years and cannot wait until quantum computers capable of breaking cryptographic signatures emerge to take action. Coinbase suggested adopting a flexible 'container' design similar to BIP-360 to gradually replace quantum-resistant signature systems. Additionally, it proposed a phased implementation of a '1-of-2' scheme, allowing the same funds to be spent using either traditional keys or quantum-resistant keys during the transition period. The scheme would also need to be compatible with multi-party computation (MPC) key-splitting mechanisms. Coinbase emphasized that dormant, lost, and Satoshi-era Bitcoin holdings represent separate governance issues, and any rescue mechanisms must also possess quantum-resistant capabilities. In January of this year, Coinbase established a Quantum Advisory Board; in July, it joined the Bitcoin Security Alliance alongside BlackRock and Strategy, committing a total of $15 million to Bitcoin's quantum-resistant upgrades. (Decrypt)