Coldcard Hack Exposes Single-Hardware Wallet Risk

The Coldcard entropy bug has exposed the risk of relying on single hardware wallets for self-custody, prompting experts to recommend multi-vendor multisignature wallets as a more secure approach.

Self-custody is an advanced practice in Bitcoin that involves users taking direct control of their funds by storing and managing their private keys. However, recent events have driven a revaluation of custody practices, with many bitcoin owners moving coins to exchanges or upgrading their self-custody setups.

Casa's CEO, Nick Neuman, claimed that 233k bitcoins were moved to safety in reaction to the Coldcard hack. To understand when self-custody makes sense and for whom, it is essential to create a personal threat model by analyzing potential threats and designing security practices accordingly.

Multi-vendor multisig theory posits that users should make sure every keypair used to construct a Bitcoin multisig is generated from a different wallet vendor. This approach minimizes trust in any single wallet vendor, protecting users from entropy failures like the one seen in Coldcard.