linux, mac and windows system entropy are all fine. obviously ony linux live usb can be done airgapped on a fresh machine never connected to a network. this is basically what a seedsigner is but unlike the tiny linux on a tiny rpi the desktop linux has at least the mouse to add entropy, and it does, by default. modern linux (5.17+ especially) mixes entropy from: - **input devices** — keyboard, mouse, touchscreen (add_input_randomness) - **network devices** — interrupt timing on packet arrival (add_network_randomness via add_interrupt_randomness) - **block devices** — disk interrupt timing (add_disk_randomness) - **rdrand/rdseed** — CPU hardware RNG if available, mixed in, not trusted exclusively - **jitter entropy** — CPU execution timing variance as a fallback source - **boot-time entropy** — saved seed from previous shutdown, fed back on boot the CSPRNG (chacha20-based) is reseeded continuously from all of these. the old blocking `/dev/random` vs non-blocking `/dev/urandom` distinction is gone since 5.17 — both are the same CSPRNG, and you cannot deplete entropy. the coldcard failure was an embedded micropython problem — no kernel entropy infrastructure, no multi-source mixing, just a misconfigured hardware RNG falling back to a deterministic yasmarang PRNG seeded from chip serial and clock. linux has the opposite architecture: assume every source is potentially weak, mix them all.