@dracoe/tail-number-gen

Converts a hex UID to a 6-character visual tail number. Identical output to the C, Go, and Python implementations in the same family.

Install

npm install @patrick_dracoe/tail-number-gen

Usage

const { uidToTail } = require('@patrick_dracoe/tail-number-gen');

uidToTail('1A2B3C4D5E6F7081');             // '3Z4P18'
uidToTail('1A2B3C4D-5E6F7081-9A2B3C4D');  // spaces and hyphens stripped
uidToTail('a1b2c3d4');                     // case-insensitive

TypeScript types are included.

API

uidToTail(uid: string): string

Accepts 1–36 hex characters. Spaces and hyphens are ignored. Short UIDs are left-padded with zeros.

Throws Error if the UID is empty or contains non-hex characters.

Algorithm

1. Strip spaces/hyphens, uppercase, left-pad to 36 hex digits
2. SHA-256 the normalized ASCII string
3. Take the first 4 bytes as a big-endian uint32
4. Reduce mod 34⁶, base-34 encode to 6 characters (alphabet excludes I and O)

No dependencies — uses Node's built-in crypto module.