DroidFS/BUILD.md

# Introduction
DroidFS relies on modified versions of the original encrypted filesystems programs to open volumes. [CryFS](https://github.com/cryfs/cryfs) is written in C++ while [gocryptfs](https://github.com/rfjakob/gocryptfs) is written in Go. Thus, building DroidFS requires the compilation of native code. However, for the sake of simplicity, the application has been designed in a modular way: you can build a version of DroidFS that supports both Gocryptfs and CryFS, or only one of the two.

# Setup
Install required packages:
```
$ sudo apt-get install openjdk-11-jdk-headless build-essential pkg-config git gnupg2 wget apksigner
```
You also need to manually install the [Android SDK](https://developer.android.com/studio/index.html#command-tools) and the [Android Native Development Kit (NDK)](https://developer.android.com/ndk/downloads) (r23 versions are recommended).

If you want a support for Gocryptfs volumes, you must install [Go](https://golang.org/doc/install) and libssl:
```
$ sudo apt-get install golang-go libssl-dev
```
For CryFS support, you need [Python](https://www.python.org):
```
$ sudo apt-get install python3
```
The code should be authenticated before being built. To verify the signatures, you will need my PGP key:
```
$ gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys AFE384344A45E13A
```
Fingerprint: `B64E FE86 CEE1 D054 F082  1711 AFE3 8434 4A45 E13A` \
Email: `Hardcore Sushi <hardcore.sushi@disroot.org>`

# Download sources
Download DroidFS source code:
```
$ git clone --depth=1 https://github.com/hardcore-sushi/DroidFS.git
```
Verify sources:
```
$ cd DroidFS
$ git verify-commit HEAD
```
__Don't continue if the verification fails!__

Initialize submodules:
```
$ git submodule update --depth=1 --init
```
[FFmpeg](https://ffmpeg.org) is needed to record encrypted video:
```
$ cd app/ffmpeg
$ git clone --depth=1 https://git.ffmpeg.org/ffmpeg.git
```
If you want Gocryptfs support, you need to download OpenSSL:
```
$ cd ../libgocryptfs
$ wget https://www.openssl.org/source/openssl-1.1.1p.tar.gz
```
Verify OpenSSL signature:
```
$ wget https://www.openssl.org/source/openssl-1.1.1p.tar.gz.asc
$ gpg --verify openssl-1.1.1p.tar.gz.asc openssl-1.1.1p.tar.gz
```
Continue **ONLY** if the signature is **VALID**.
```
$ tar -xzf openssl-1.1.1p.tar.gz
```
If you want CryFS support, initialize libcryfs:
```
$ cd app/libcryfs
$ git submodule update --depth=1 --init
```

# Build
Retrieve your Android NDK installation path, usually something like `/home/\<user\>/Android/SDK/ndk/\<NDK version\>`. Then, make it available in your shell:
```
$ export ANDROID_NDK_HOME="<your ndk path>"
```
Start by compiling FFmpeg:
```
$ cd app/ffmpeg
$ ./build.sh ffmpeg
```
## libgocryptfs
This step is only required if you want Gocryptfs support.
```
$ cd app/libgocryptfs
$ OPENSSL_PATH="./openssl-1.1.1p" ./build.sh
 ```
## Compile APKs
Gradle build libgocryptfs and libcryfs by default.

To build DroidFS without Gocryptfs support, run:
```
$ ./gradlew assembleRelease -PdisableGocryptfs=true
```
To build DroidFS without CryFS support, run:
```
$ ./gradlew assembleRelease -PdisableCryFS=true
```
If you want to build DroidFS with support for both Gocryptfs and CryFS, just run:
```
$ ./gradlew assembleRelease
```

# Sign APKs
If the build succeeds, you will find the unsigned APKs in `app/build/outputs/apk/release/`. These APKs need to be signed in order to be installed on an Android device.

If you don't already have a keystore, you can create a new one by running:
```
$ keytool -genkey -keystore <output file> -alias <key alias> -keyalg EC -validity 10000
```
Then, sign the APK with:
```
$ apksigner sign --out droidfs.apk -v --ks <keystore> app/build/outputs/apk/release/<unsigned apk file>
```
Now you can install `droidfs.apk` on your device.