The on-device settings PIN (devices.settings_pin, minted at pairing) and the pairing code
assigned to imported devices both came from
`Math.floor(100000 + Math.random() * 900000)`.
Math.random is not a CSPRNG. V8 implements it as xorshift128+, whose internal state is
recoverable from a handful of consecutive outputs, and every call in a process draws from
that one shared stream. Both values are also observable by ordinary users — settings_pin
is returned in device API responses today — so a user who collects a few outputs could
predict the values minted around them, including for other tenants.
lib/numeric-code.sixDigitCode() uses crypto.randomInt, which is CSPRNG-backed and
rejection-samples so the distribution stays uniform. Range is 100000..999999 inclusive,
identical to the old expression, so codes are still exactly six digits with no leading
zero — the on-device keypad and pairing UI are unchanged.
Deliberately NOT converted, because neither gates access: the image-generation seed in
lib/image-gen.js, and the anti-burn-in pixel jitter inside generated widget HTML.
Also unchanged: the settings_pin backfill in db/database.js, which uses SQLite's random()
— that is ChaCha20 seeded from OS entropy, not a weak PRNG.
This is the generator half of the finding only. The separate half — that settings_pin is
returned to every workspace member, including read-only roles — is a response-shape change
and waits on the consumer enumeration.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
