COLDCARD EXPLAINS HOW THE SEED GENERATION BUG HAPPENED Coinkite says the issue was not with Bitcoin’s cryptography itself, but with how COLDCARD generated wallet seeds. During the March 2021 libNgU migration, the wallet accidentally used a weaker software random number generator instead of the device’s dedicated hardware random number generator when creating new seed phrases. That reduced the amount of randomness protecting some wallets, making certain seeds far easier to guess than intended. The bug affected seed generation beginning in March 2021. Mk3 devices were the most exposed. Mk4, Q, and Mk5 mixed in additional hardware-generated randomness, providing significantly stronger protection, though they still relied on the same software component afterward. Coinkite says the mistake happened because two pieces of software used the same function name, allowing the wrong one to be selected during the build process without triggering an error. The company has now changed the build process so this cannot happen again.