ByteHook: Advanced Bytecode Instrumentation Workbench

ByteHook is a zero-dependency Java bytecode manipulation tool powered by the JDK 25 ClassFile API. It allows for live instrumentation, runtime transformation via a Java Agent, and visual verification through a side-by-side decompiler GUI.

Modules

• bytehook-core: The transformation engine.
• bytehook-decompiler: A basic source reconstruction engine for verification.
• bytehook-agent: A Java Agent for runtime instrumentation.
• bytehook-cli: Command-line tool for offline class modification.
• bytehook-gui: A JavaFX workbench for visual bytecode analysis.

Quick Start

1. Build the Project

./gradlew assemble

2. Use the Visual Workbench (GUI)

Load a .class file, type a message, and see the injected code instantly.

./gradlew :bytehook-gui:run

3. Use the Java Agent (Runtime)

Instrument any class starting with TestApp at load-time.

java -javaagent:bytehook-agent/build/libs/bytehook-agent.jar="My Hook" TestApp

4. Use the CLI (Offline)

Modify a .class file and save it as -hooked.class.

java -cp bytehook-cli/build/libs/bytehook-cli.jar:... org.bytehook.cli.Main MyClass.class "Injected!"

Features

• JDK 25 Native: No external dependencies (no ASM, no ByteBuddy).
• Live Diff View: GUI shows original vs. instrumented source side-by-side.
• AOP Hooks: Easy method entry/exit interception.
• High-Fidelity: Preserves original logic while injecting synthetic instructions.