decompile

Decompile is the process of translating machine code or binary executables into a higher-level representation, such as source code or an intermediate form. It is used in reverse engineering, software maintenance, malware analysis, vulnerability discovery, and interoperability efforts when the original source code is unavailable.

The decompilation process typically begins with disassembly to recover the instruction stream, followed by control-flow reconstruction, data-type inference, and the reassembly of high-level constructs such as loops, conditionals, and function boundaries. Decompilers aim to produce readable code that is functionally equivalent to the input binary, but the result is often approximate. Information such as variable names, comments, and exact program structure may be lost or altered during compilation, optimization, and obfuscation, making the recovered code imperfect and sometimes difficult to interpret.

Decompiled output is usually presented as source code in a high-level language (for example C or C-like pseudocode) or as an intermediate representation suitable for analysis. For bytecode-based systems (such as Java or .NET), decompilers attempt to recover code that resembles the original source language more closely, though it may still require manual refinement.

Tools and techniques used in decompilation include standalone decompilers, integrated into reverse-engineering suites, as well as frameworks that support custom analysis. Notable examples include Ghidra, RetDec, and Snowman, as well as specialized decompilers for Java and Android apps. Decompilation can be hindered by aggressive optimizations, obfuscation, packing, or virtualization.

Legal and ethical considerations vary by jurisdiction and context. While decompilation can support interoperability and security research, it may be restricted by copyright, licensing terms, or anti-circumvention laws. Users should respect applicable laws and licenses.