In August 2026, days after the Coldcard entropy failure became public, Stacker News user @tokyo_vyse made a proposal: stop trusting any single hardware vendor to stay bug-free for the lifetime of your wallet. Instead, build a 2-of-3 multisig where the third key is not a hardware wallet at all, but a Tails plus Electrum USB stick.<\/p>\n
The idea is exotic. It is also the logical endpoint of the vendor-diversification thesis, and it pairs directly with our Tails cold wallet guide<\/a>.<\/p>\n First, the verified facts, because the scale matters. In late July 2026, a firmware bug became public: since March 2021, Coldcard seed generation had silently fallen back to a software pseudo-random generator instead of the device’s hardware randomness source. The result was roughly 40 bits of entropy on Mk2 and Mk3 devices running firmware 4.0.1 through 4.1.9, and roughly 72 bits on Mk4, Mk5, and Q, against a design target of 128 bits. On July 30, attackers drained about 1,083 bitcoin in a single roughly 40-minute sweep, with later estimates putting total losses near $110 million. Patched firmware shipped shortly after (5.6.0 for Mk4 and Mk5, 1.5.0Q for Q, 4.2.0 for Mk3), and affected users were urged to generate new seeds and move funds immediately.<\/p>\n One allegation in the Stacker News thread deserves careful labeling: the claim that the entropy function was botched specifically in the move away from GPL, removing the incentive for public source review. That is an unverified community allegation. The verified part is the bug itself, the losses, and the vendor’s response.<\/p>\n The poster’s argument runs like this. With AI systems uncovering bugs faster than ever, betting that any single hardware vendor stays bug-free for the decades your wallet must last is unwise. Multisig<\/a> is the way out: in a 2-of-3, one vendor’s catastrophic bug costs you a key, not your coins.<\/p>\n That thesis is sound independent of the Coldcard specifics. It is the same reason this site recommends mixing vendors in every multisig build. The Tails stick is the thesis taken one step further: make the third key a completely different technology stack, so no single vendor’s failure mode, hardware or software, can touch a threshold of keys.<\/p>\n The suggested setup is a 2-of-3 with two hardware wallets plus a Tails USB stick running Electrum:<\/p>\n The descriptor-backup point is worth repeating because it is where multisig builders most often fail. Seeds alone do not recover a multisig. The descriptor, with every cosigner’s xpub, must exist somewhere recoverable. Digital copies in multiple places are fine, since xpubs reveal addresses but cannot spend. Seed words are not enough<\/a>, and this is exactly why.<\/p>\n A Tails stick is not a hardware wallet. It has no secure element, no tamper-evident packaging, no dedicated signing screen. What it has is a completely independent software stack, amnesiac by default, running on commodity hardware anyone can inspect. That is a different security profile, not a strictly better one.<\/p>\n Operationally, it is also more work. Booting Tails, moving PSBTs by SD card, and maintaining the persistent volume is friction that a third hardware wallet does not have. Friction you skip becomes the weak link, so be honest about whether you will actually do the ceremony every time.<\/p>\n For most people, three hardware wallets from two or three vendors remains the practical diversification play. Compare hardware options in the Die beste Bitcoin-Wallet<\/a> guide. The Tails third key is for the builder who wants maximum vendor independence and will maintain the operational discipline it demands. Our Tails cold wallet guide<\/a> covers the stick setup in detail, and the compatibility checker<\/a> shows which coordinators work with Electrum-based signers.<\/p>\n If you are still deciding which shape fits your threat model, the multisig wizard<\/a> walks you through it in six questions.<\/p>\nThe context: what actually happened with Coldcard<\/h2>\n
The thesis: multisig as vendor diversification<\/h2>\n
The proposal: Tails plus Electrum as key three<\/h2>\n
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The honest tradeoffs<\/h2>\n