TOTP in BQN

This is a simple implementation of the TOTP algorithm in BQN, including most of its dependencies. Without comments, the code in totp.bqn weighs in at around 50 lines; the implementation follows the following RFC's:

• RFC 3174 for SHA1
• RFC 4648 for Base32 decoding
• RFC 2104 for HMAC
• RFC 4226 for HOTP
• RFC 6238 for TOTP

For ease of use—but don't actually use this, please—a main.bpn file is provided that can read input from stdin:

$ echo "ZYTYYE5FOAGW5ML7LRWUL4WTZLNJAMZS" | bqn main.bqn
024999

Right now, the implementation is locked to a time step of 30, six digits, and SHA1 as the hashing algorithm. Incidentally, this covers 100% of my real-world use-cases for TOTP, so it seems like a sane minimal implementation.

Inspirations

The venerable mintotp.