hdm-am

A Rust client for the Armenian fiscal cash register protocol — the spec published by the State Revenue Committee of Armenia (ՊԵԿ) for integrating external (commercial) software with fiscal cash registers (Հսկիչ Դրամարկղային Մեքենա — HDM, ՀԴՄ).

This crate is the core library of the hdm-am workspace: the wire framing, encryption, and one typed request/response per operation. The CLI (hdm-am-cli), HTTP bridge (hdm-am-bridge), and GUI (hdm-am-app) all build on top of it.

Scope

The crate speaks the HDM TCP protocol directly:

• 12-byte fixed header with D5 80 D4 B4 D5 84 magic ("ՀԴՄ" in UTF-8), 2-byte protocol version, 1-byte operation code, 2-byte big-endian payload length.
• 3DES-ECB-PKCS7-encrypted JSON payloads.
• Two-key model: a SHA-256-derived password key for operator login (and the operator/department listing), a session key returned by login for everything after.
• All 16 operations from spec v0.7.3.

It does not handle the surrounding business logic — selecting an HDM device, persisting fiscal receipts, deciding what to print. That belongs to the consumer.

Features

• schema — derive [schemars::JsonSchema] for every wire request/response type. Off by default to keep schemars out of the default dependency graph. The dump-schema example regenerates docs/schema/*.json from these impls.

Documentation

See the workspace README for the full project overview (CLI, HTTP bridge, GUI, TypeScript clients), per-device operation coverage, and the archived protocol specifications.

License

Licensed under either of Apache-2.0 or MIT at your option.