CH-J SM Mobile

# SM Mobile — CH-J

SM Mobile is a standalone Android and iOS edition of CH-J Server Manager, built with Flutter and Dart. It connects directly to servers over SSH and SFTP, without an account, cloud service, or telemetry. The project is currently a development alpha (0.0.1). The desktop application is not a dependency.

## Download alpha

| Platform / artifact | Download | Installation |
| --- | --- | --- |
| Android 11+ | [Download APK](https://www.sm.ch-j.cz/download.php?id=1d5620956f34130e1e1d67d8&edition=mobile&lang=cs) | Direct installation; signed alpha package |
| iOS/iPadOS 15+ | [Download unsigned IPA](https://www.sm.ch-j.cz/download.php?id=75cd6f6c91f9244da4e116da&edition=mobile&lang=cs) | Requires your own Apple signing and provisioning |
| Android distribution tools | [Download AAB](https://www.sm.ch-j.cz/download.php?id=d71915fa77047540b2fa2c52&edition=mobile&lang=cs) | Cannot be installed directly on a phone |
| iOS simulator on Apple Silicon Mac | [Download simulator ZIP](https://www.sm.ch-j.cz/download.php?id=3d6da43cbef7dbf8c22d5b25&edition=mobile&lang=cs) | Simulator only; cannot be installed on iPhone or iPad |

**Development alpha:** back up important data before testing. See the [official mobile download page](https://www.sm.ch-j.cz/cs/?edition=mobile) for current build details and checksums.

## Development status and downloads

SM Mobile is an actively developed **alpha**, version `0.0.1`. The official catalog checked on **October 16, 2026** lists build `sm-mobile-20261016T050549Z-3678f2a05fa9`. It is available for testing; production readiness and physical-device validation remain incomplete. Use the [official mobile download page](https://www.sm.ch-j.cz/cs/?edition=mobile) for current packages, build IDs, SHA-512 values and Android signing-certificate details.

| Artifact on the official website | Purpose and installation status |
| --- | --- |
| Signed Android release APK | Direct installation on Android 11+; allow installation from the browser if Android requests it |
| Android release AAB | Distribution tooling; cannot be installed directly on a phone |
| Unsigned iOS IPA (`arm64`) | Requires your own Apple signing and provisioning; not directly installable from the website |
| iOS simulator application ZIP (`arm64`) | Apple Silicon Mac simulator; cannot be installed on iPhone or iPad |

A signed Android release package is still an alpha product. Test on non-production servers and prepare appropriate backups.

## Platforms and implemented features

The project targets **Android 11+ (API 30+)** and **iOS/iPadOS 15+**, with phone and tablet layouts. *In development (not yet published):* one adaptive layout for phones, tablets, split-screen windows and foldables. It follows the window's available size in logical pixels, never a device model: windows narrower than 600 logical pixels use bottom navigation, wider windows and short landscape windows use a navigation rail, and from 840 logical pixels the server list stays beside the selected tool. A half-folded fold or a hinge reported by the system splits the content on either side of it. Rotation, resizing and folding keep the SSH session, terminal, SFTP directory and unsaved input. The iOS project enables both iPhone and iPad device families. Physical iPad, foldable and iPhone Duo validation remains outstanding.

Implemented in the current Flutter / Dart application:

- Direct SSH access with password or private-key authentication, SHA-256 host-key verification and one active connection.
- An interactive PTY terminal with CTRL, ALT, ESC, TAB and arrow controls.
- SFTP browsing, upload/download, rename, directory creation and confirmed deletion, with transfer cancellation and no overwrite of existing destinations.
- *In development (0.0.3, not yet published):* a code and text editor (Re-Editor with Re-Highlight grammars) for remote files over SFTP and for files on the device (iOS/iPadOS Files and file providers, Android Storage Access Framework). It keeps encoding (UTF-8, UTF-8 BOM, UTF-16 LE/BE, Windows-1250/1252, ISO-8859-1/2), line endings and the final newline; detects changes made elsewhere before saving; saves remote files through a temporary file and an atomic rename while keeping permissions; offers find/replace with case and regular expressions, go to line, folding, JSON/YAML/XML validation and recent/favorite files. Images, safe SVG, archives (listing only), certificates (basic information only), notebooks and a hex view are shown in the app; PDF, office documents and media open in the system viewer.
- An AES-256-GCM encrypted local Vault, master-password unlock, optional OS-protected biometric unlock and automatic locking that disconnects SSH. *In 0.0.3:* master password of 4–64 characters with a strength indicator, password change (with a new data key), Argon2id key derivation, biometric unlock that starts automatically and never falls back to the device passcode.
- Desktop-compatible version 1 JSON profile import/export without credentials or trusted host keys.
- Foreground Linux monitoring for CPU, RAM, root filesystem usage, uptime, load and SSH command response time, with readable units and load gauges.
- IPv4/IPv6 DNS lookup and TCP connection checks in the published 0.0.1. *In development (0.0.2/0.0.3, not yet published):* on-device network diagnostics with real ICMP / ICMPv6 echo ping (count, interval, timeout, payload size; per-packet RTT, min/avg/max and loss), real traceroute with TTL / hop limit (three probes per hop, up to 30 hops by default, `*` for no reply), and TCP connect with DNS lookup. Automatic, IPv4 or IPv6, cancellable at any time, without root, a server or a cloud service. *In 0.0.3:* TCP connect ping and ICMP ping with presets or continuous runs, IPv4 + IPv6 measured side by side, per-attempt log, statistics (median, standard deviation, jitter, P95), RTT chart and TXT/CSV/JSON export; ICMP ping with TTL/hop limit and Don't Fragment; traceroute over ICMP, UDP and TCP (TCP on iOS/iPadOS only), repetitions, reverse DNS and comparison with the previous run.
- Czech, German and English interfaces, with light, dark and system themes.

### Current limits and validation

There is one active SSH connection. SFTP uses POSIX paths, refuses symlink traversal and existing destination files, and deletes directories non-recursively. Release 0.0.1 has no text editor; 0.0.3 adds one (not yet published). There is no CSV import, desktop plugin system, local Hash & Checksum tool, automatic updater or persistent background monitoring. Changed trusted host keys block connection; there is currently no UI for rotating or removing them.

The [recorded test results](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FTESTING.md) cover automated tests, local OpenSSH and Linux integration, an Android emulator and an iPhone simulator. They do not establish physical-device biometric behavior, iPad operation, mobile-network IPv6, large real-device transfers or a complete accessibility audit. These areas still require validation.

## Official links and source code

- [SM Mobile — official website](https://www.sm.ch-j.cz/cs/?edition=mobile)
- [SM Mobile — releases and downloads](https://www.sm.ch-j.cz/cs/releases/?edition=mobile)
- [SM Mobile — source code browser and source archives](https://www.sm.ch-j.cz/cs/source/?edition=mobile)
- [SM Mobile — GitHub](https://github.com/ch-j-code/SM-Mobile)

This GitHub repository contains only this README. Application source code, source archives, documentation, and builds are published on the official website. To follow the development and build instructions below, download and extract the mobile source archive from the source browser, then open the extracted project directory.

## CH-J Ecosystem — Desktop & Mobile

CH-J Server Manager is the separate desktop application for Windows, macOS, and Linux. The mobile and desktop applications can each be used independently; neither requires the other.

| | CH-J Server Manager | SM Mobile |
| --- | --- | --- |
| Platforms | Windows, macOS, Linux | Android, iOS/iPadOS; phones and tablets |
| Technology | Electron / JavaScript | Flutter / Dart |
| Server access | Multiple SSH sessions, terminal, SFTP and Monaco editing | One SSH connection, PTY terminal, SFTP browsing and transfers |
| Tools | Extended diagnostics, local hashing and first-party management plugins | Foreground Linux monitoring, DNS/TCP diagnostics |
| Profile exchange | Version 1 JSON and desktop CSV | Shared version 1 JSON only |
| Status | Development alpha | Development alpha; see package restrictions above |
| Project README | [Desktop README](https://github.com/ch-j-code/CH-J-Servermanager#readme) | [Mobile README](https://github.com/ch-j-code/SM-Mobile#readme) |

Shared profile JSON carries only name, host, username and port. The applications use separate Vault formats; encrypted Vault files are not interchangeable.

- [CH-J Server Manager — official website](https://www.sm.ch-j.cz/cs/)
- [CH-J Server Manager — GitHub](https://github.com/ch-j-code/CH-J-Servermanager)
- [CH-J Server Manager — desktop source code](https://www.sm.ch-j.cz/cs/source/)

## Requirements

- Flutter with Dart compatible with the SDK constraint in `pubspec.yaml` (`>=3.10.0 <4.0.0`).
- For Android development: OpenJDK 17, Android SDK and platform tools, and an Android device or emulator. Android Studio is optional; the command-line tools can be used instead.
- For iOS development: macOS, Xcode, CocoaPods, and an iOS device or simulator.
- Python 3 for the build and integration test scripts.

The configured minimum versions are Android 11 (API 30) and iOS/iPadOS 15; see the platform and validation limits above. Run `flutter doctor -v` to check your development environment before building.

## Getting started

Run the following commands from the project directory:

```sh
flutter pub get
flutter devices
flutter run -d <device-id>
```

Replace `<device-id>` with a device listed by `flutter devices`. To use an Android emulator, list available emulators with `flutter emulators` and launch one with `flutter emulators --launch <emulator-id>`. On macOS, you can open the iOS Simulator with `open -a Simulator`.

For VS Code, install the Dart and Flutter extensions, open `SM Mobile.code-workspace`, select a device in the status bar, and press F5.

## Using the application

1. Choose a language, read the security recommendations and the full CH-J license version 1.14, and explicitly accept the license.
2. Create a Vault with a master password (12–128 characters in 0.0.1; 4–64 characters in 0.0.3). This password cannot be recovered. You can enable biometric unlock later in Settings.
3. Add a server. Hostnames are stored as entered; DNS results are never written back to profiles. IPv6 addresses can also be entered in square brackets.
4. Select a server and connect using a password or a securely stored private key. Private key passphrases are requested when connecting and are not stored.
5. Verify the SSH host key fingerprint through an independent channel before accepting it for the first time. A change to a known host key blocks the connection.
6. Use the terminal with a real PTY shell. CTRL and ALT apply to the next input only; ESC, TAB, and arrow keys are available on the scrollable toolbar.
7. Use Files to browse over SFTP, upload files, download through the system share/save interface, rename items, create directories, and delete items after confirmation. Directory deletion is non-recursive. Existing destination files are not overwritten; choose a different name.
8. Open Monitor to collect Linux metrics while that screen is visible and the application is in the foreground. Diagnostics offers IPv4/IPv6 DNS and TCP checks (0.0.1); the development versions add ping and traceroute over IPv4 or IPv6, run from the device itself, plus details of the active SSH connection. TCP connect is not an ICMP ping; ping and traceroute use real ICMP / ICMPv6 through the operating system's unprivileged ICMP sockets.

On phones, Servers, Terminal, and Files appear in the bottom navigation bar; the last item opens Monitor, Diagnostics, and Settings. Wider displays use a scrollable navigation sidebar. Settings offers Czech, German, and English, along with light, dark, and system themes.

## Importing and exporting profiles

Settings → Import / Export profiles uses the desktop-compatible `chj-server-profiles` JSON format, version 1. Each profile contains only `name`, `host`, `username`, and `port`. Passwords, private keys, passphrases, and host key fingerprints are never transferred.

Imports are limited to 5 MiB and 10,000 records. A preview lets you skip duplicates, update existing profiles, or create copies. Updating a profile clears its credentials. Equivalent IPv6 representations are normalized only for duplicate comparison; hostnames are not resolved. Configure authentication after importing or duplicating profiles. CSV is not supported in the mobile edition.

## Building and validation

Use the build script when preparing builds to share. Each run creates a new build ID, refreshes third-party license notices, and runs static analysis and tests:

```sh
python3 tool/build.py all
```

The `all` target requires macOS and both Android and iOS toolchains. It produces the following development artifacts:

- APK: `build/app/outputs/flutter-apk/app-debug.apk`
- App bundle: `build/app/outputs/bundle/debug/app-debug.aab`
- iOS simulator application: `build/ios/iphonesimulator/Runner.app`

The APK and app bundle produced by this command are debug builds, not release packages. To build a single target, use `apk`, `aab`, or `ios-simulator` instead of `all`.

You can also run the checks and builds individually:

```sh
flutter pub get
flutter analyze
flutter test
flutter build apk --debug
flutter build appbundle --debug
flutter build ios --simulator
```

### Website distribution

```sh
python3 tool/build.py distribution
# Optional simulator build with the same build ID:
flutter build ios --simulator --debug
python3 tool/prepare_release.py
```

This target requires macOS, both toolchains, and `android/key.properties`. It creates a signed release APK and AAB plus an **unsigned** iOS device application, all with the same new build ID. An unsigned IPA made from that application requires your own Apple signing and provisioning before installation; it is not an installable Ad Hoc release. The AAB is for distribution tooling, not direct installation. Use the APK on Android.

The website offers separate Desktop and Mobile editions and a source browser with the exact mobile build snapshot. Source archives exclude signing keys, password configuration, provisioning profiles, local SDK paths, caches and build outputs. Keep the Android release keystore and its password configuration backed up privately; future Android updates must use the same signing identity.

### Android release

Create your own `android/key.properties` with `storeFile`, `storePassword`, `keyAlias`, and `keyPassword`, then run:

```sh
python3 tool/build.py aab --release
```

Signing keys and the password configuration file are excluded by `.gitignore`. Release builds do not fall back to a debug signing identity.

### iOS release

Prepare an unsigned device build:

```sh
python3 tool/build.py ios
```

Open `ios/Runner.xcworkspace`, configure your own development team, provisioning, and distribution certificate, then use Xcode's Archive and App Store Connect workflow. The script does not publish anything automatically.

Direct `flutter build` commands retain the existing build ID. Do not reuse that ID for a different distributed build; use `tool/build.py` to generate a new one.

## Testing

`flutter test` covers models, profile import/export, Vault cryptography, host key verification, license acceptance, application lifecycle, and widgets. Six network scenarios are skipped unless explicitly enabled. A successful standard test run does not replace these integration tests.

### Local OpenSSH integration tests

On macOS or Linux, with OpenSSH available and port 22229 free, run:

```sh
python3 tool/test_openssh.py
python3 tool/test_openssh.py --device <ios-simulator-id>
python3 tool/test_openssh.py --device <android-device-id> --android
```

These are alternative invocations for the default test runner, an iOS simulator, or an Android emulator. Replace device placeholders with the appropriate IDs.

The script creates temporary keys in a private directory, starts a server listening only on `127.0.0.1`, and stops it after testing. It does not configure the system SSH server or modify `~/.ssh`. The test account is the current local user. The fixture is not chrooted, so test operations stay within a temporary directory. Run it on a development machine. Docker is not required.

For physical devices, follow the scenarios in [Testing](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FTESTING.md) against your own isolated test server.

### Optional Linux container tests

An optional container test covers a real Linux environment, SSH password authentication, and monitoring. Docker and Colima are test tools, not dependencies of the application or its builds.

With a Docker-compatible runtime running, use:

```sh
python3 tool/test_linux.py --context <docker-context>
```

For example, on macOS with Colima installed:

```sh
colima start --profile sm-mobile-test --vm-type vz --cpu 2 --memory 2 --disk 10
python3 tool/test_linux.py --context colima-sm-mobile-test
colima stop --profile sm-mobile-test
```

The fixture listens only on `127.0.0.1:22239`, uses a randomly generated password for each run, removes the container automatically, and pins the image by digest. See the [OpenSSH image documentation](https://docs.linuxserver.io/images/docker-openssh-server/) and [Colima project](https://github.com/abiosoft/colima) for the underlying tools.

## Documentation

The following documents are available in the official mobile source browser and in the downloaded source archive:

- [Source audit](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FAUDIT.md)
- [Security](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FSECURITY.md)
- [Dependencies](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FDEPENDENCIES.md)
- [Test scenarios and results](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FTESTING.md)
- [Resolved components](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FRESOLVED_COMPONENTS.md)

## Security, backups and license

Vault encryption uses AES-256-GCM with a random data key, wrapped using a key derived from the master password through PBKDF2-HMAC-SHA256 (600,000 iterations); 0.0.3 uses Argon2id (64 MiB, 3 iterations) for new and changed passwords and upgrades existing Vaults after the next unlock. OS secure storage protects the encrypted envelope; optional quick unlock stores its data key separately under OS authentication controls. Private-key passphrases are not saved. Locking disconnects SSH and clears the terminal buffer. Physical-device biometric validation remains outstanding; see the [security model and limits](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FSECURITY.md).

Verify the first SSH host-key fingerprint through an independent channel. A changed known key blocks the connection before authentication. The master password cannot be recovered. JSON profile export is not a backup of credentials, private keys, trusted host keys or remote data. Prepare and test appropriate backups before risky operations; the application does not guarantee backup existence or recoverability.

The application displays the operational guidance and requires explicit license acceptance before first use and again for each new build. The guidance is informational and non-binding, is separate from the license, and does not require separate acceptance.

This edition is licensed under the **CH-J Proprietary Software License 1.14**. See [LICENSE](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=LICENSE) for the full terms and [NOTICE](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=NOTICE) for distribution notices.

Third-party components retain their own licenses. Full license texts are available in [Third-party notices](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=assets%2Flegal%2Fthird_party_notices.txt), with a component list in [Resolved components](https://www.sm.ch-j.cz/cs/source/?edition=mobile&path=docs%2FRESOLVED_COMPONENTS.md). They are also available in the application under Settings → Component licenses. The security recommendations are adapted from the CH-J desktop project in Czech, German, and English. The license remains in its original English; third-party rights and notices remain separate.

## Topics

`#flutter` `#dart` `#android` `#ios` `#ipados` `#ssh` `#ssh-client` `#sftp` `#terminal` `#server-management` `#server-monitoring` `#network-diagnostics`