MechaCat02 87c5cedf3c Add RFC 6238 one-time codes ...

WebUntis authenticates the mobile app not with a password but with a static
base32 key, from which every request derives a fresh code. That is the
credential an always-on server wants: it works under the school's SSO, needs
no session, and expires only when a new key is generated.

Implemented rather than pulled in. It is HMAC-SHA1 plus a truncation,
node:crypto has the hard part, and a dependency that handles a credential is
one worth not having. The tests are the RFC's own vectors, which validate the
base32 table as much as the arithmetic.

The code comes back zero-padded, as a string. One in ten begins with a zero
and a JSON number would drop it, which is a login that fails a tenth of the
time and looks like a server fault.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

2026-09-17 20:43:24 +02:00

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