Presswerk

High-Assurance Local Print Router/Server

Presswerk (German: press works / printing press) is a cross-platform mobile app that discovers network printers, manages print jobs, processes documents, and exposes your phone as a network print server.

Built with formal verification (Idris2 ABI proofs), memory-safe Rust throughout, encrypted local storage, and a complete audit trail.

Table of Contents

• Features
• Architecture
• Crate Dependency Graph
• Tech Stack
• Project Stats
• Quick Start
• Formal Verification
• Security
• Container
• License
• Architecture

Features

• Easy Mode UI — 3-tap printing (Choose file → auto-select printer → PRINT); giant touch targets for elderly/children

• Printer Discovery — mDNS/DNS-SD, SNMP, manual IP entry; remembers printers across restarts

• IPP Printing — Full RFC 8010/8011 client with all settings (copies, duplex, colour, paper, orientation)

• Protocol Downgrade — IPPS → IPP → LPR → Raw TCP; always starts from most secure

• Print Doctor — 6-step diagnostic wizard (network → discovery → reachable → IPP → ready → test print)

• Retry Engine — Exponential backoff with jitter, circuit breaker, network self-healing

• Universal Connectivity — USB, Bluetooth, Wi-Fi Direct, NFC, Serial, Parallel, FireWire, Thunderbolt, and more

• Document Processing — PDF read/merge/split/rotate/crop, image resize/enhance, text-to-PDF, format auto-conversion

• Document Scanning — Camera capture with edge detection, perspective correction, binarisation, OCR

• Print Server Mode — Phone advertises itself as a network printer; other LAN devices can print to it

• Encrypted Storage — age (X25519) encryption at rest for all local data

• Audit Trail — Append-only encrypted SQLite log of every operation

• Formal Verification — Idris2 ABI proofs for protocol correctness, encryption invariants, and bridge safety

• Human Error Messages — Plain English with actionable suggestions, not raw technical strings

Architecture

presswerk/
├── Cargo.toml # Workspace root (6 crates)
├── Dioxus.toml # Dioxus CLI config (iOS/Android bundle IDs)
├── Justfile # Build recipes
├── crates/
│ ├── presswerk-core/ # Shared types, errors, config
│ ├── presswerk-security/ # Encrypted storage, audit trail, TLS certs
│ ├── presswerk-document/ # PDF ops, image processing, scanning, OCR
│ ├── presswerk-print/ # IPP client/server, mDNS discovery, job queue
│ ├── presswerk-bridge/ # Native platform FFI (iOS objc2 + Android JNI)
│ └── presswerk-app/ # Dioxus UI (10 pages, routing, state)
├── src/abi/ # Idris2 ABI proofs (5 files, no Admitted)
│ ├── Types.idr # Core types, C ABI sizes, injectivity
│ ├── Protocol.idr # IPP ops, job state machine
│ ├── Encryption.idr # encrypt/decrypt roundtrip, bounds
│ ├── Layout.idr # Struct alignment proofs
│ └── Bridge.idr # Toll-free bridging, keychain, threads, JNI
├── ffi/zig/ # Zig FFI (C-compatible, 5 tests)
├── generated/abi/ # Auto-generated C headers
├── .machine_readable/ # SCM metadata (STATE, META, ECOSYSTEM, etc.)
└── .bot_directives/ # Bot directives (7 bots)

Crate Dependency Graph

presswerk-core (no internal deps — thiserror, serde, uuid, chrono)
↑
presswerk-security (→ core; age, ring, rustls, rusqlite)
↑
presswerk-document (→ core; lopdf, printpdf, image, imageproc, ocrs)
↑
presswerk-print (→ core, security; ipp, mdns-sd, tokio)
↑
presswerk-bridge (→ core; objc2 [iOS], jni [Android])
↑
presswerk-app (→ ALL above; dioxus with mobile feature)

Tech Stack

Layer	Technology	Purpose
UI Framework	Dioxus 0.7+	Pure Rust, React-like, mobile-native
Print Protocol	IPP/1.1 + LPR + Raw TCP	Protocol downgrade chain, retry engine
Discovery	mdns-sd	mDNS/DNS-SD printer scanning
PDF	lopdf + printpdf	Read/write/manipulate PDFs
Image	image + imageproc	Processing pipeline
Scanning	Canny edge + Hough + perspective correction	10-step pipeline
OCR	ocrs (pure Rust neural)	No C deps (Tesseract-free)
Security	age + ring + rustls	Encryption, TLS, integrity
Storage	rusqlite (bundled)	Persistent job queue + audit trail
ABI	Idris2	Formal verification (5 proof files)
FFI	Zig	C-compatible implementation
iOS Bridge	objc2 + objc2-ui-kit	UIKit, Security.framework
Android Bridge	jni + ndk-context	PrintManager, Intents, Keystore

Project Stats

• 46 Rust source files (10,749 lines)

• 5 Idris2 ABI proof files (0 Admitted, 0 believe_me)

• 3 Zig FFI files

• 68 unit tests (47 print + 14 security + 7 document)

• 7 criterion benchmarks (3 security + 3 print + 1 document)

• 21 GitHub Actions workflows (CI, security, release, benchmarks, CodeQL, Scorecard)

• 0 clippy warnings, 0 audit vulnerabilities

• 0 critical security findings (panic-attack)

Quick Start

# Desktop development
just dev
# Run tests (library crates only — avoids desktop linker deps)
just test-libs
# Full CI check (test + lint + fmt)
just ci
# Clippy lint
just lint
# Run benchmarks
just bench
# Security scan
just assail
# Type-check Idris2 ABI proofs
just verify-abi
# iOS (requires macOS + Xcode)
just ios
# Android (requires NDK)
just android

Formal Verification

The Idris2 ABI layer provides compile-time proofs for:

File	What It Proves
Types.idr	Core types with C ABI sizes, platform detection, injectivity
Protocol.idr	IPP op-code injectivity, job state machine transitions, terminal states
Encryption.idr	encrypt/decrypt roundtrip identity, ciphertext bounds, key separation
Layout.idr	Struct memory layout alignment for FFI boundary safety
Bridge.idr	Toll-free bridging (iOS), keychain semantics, thread safety, JNI invariants

Every unsafe block in Rust references the specific ABI proof that justifies it.

Security

• Encrypted storage — age (X25519) encryption at rest

• Audit trail — Append-only encrypted SQLite log

• TLS certificates — Ed25519 self-signed for print server mode

• Document integrity — SHA-256 hashing with content-addressed storage

• Formal proofs — No Admitted, no believe_me, no transmute

• SAFETY comments — Every unsafe block references Bridge.idr/Layout.idr proofs

Container

# Build (Podman, chainguard base)
podman build -f Containerfile -t presswerk:latest .# Run headless print server
podman run --rm -p 631:631 -v presswerk-data:/app/data presswerk:latest
# Seal and sign
selur seal presswerk:latest
cerro-torre sign presswerk:latest

License

SPDX-License-Identifier: CC-BY-SA-4.0

Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>

Architecture

See TOPOLOGY.md for a visual architecture map and completion dashboard.