Hello readers, hope you all are doing fine!😀 Here's a blog on Decompilers, discussing on, whether they are ethical or unethical…..So, get ready to gain some knowledge and get on with the blog! Happy Reading!🙌
Have you ever wondered what is Decompiler? what is it used for? and so on…so most of your questions will be answered here, read till the end to get the complete context of this blog!🤩
So, lets begin with,
What is a Decompiler 🤔?
- A decompiler is a computer program that takes an executable/runnable file as input, and attempts to create a high level language source file which can be recompiled successfully.The decompiler is that part of reverse engineering.
- The term decompiler is most commonly used to describe a program which translates executable programs (the output from a compiler) into source code in a (relatively)High level language which, when compiled, will produce an executable whose functioning is that same as the original executable program/original program.
Where will the decompiler be used?
- The decompiler is the reverse process of the compiler. Decompilers are creating high level language from the low level language or machine code .
- At the fundamental level, it simply needs to know the machine/low level language code and again write it into a high level language, but this all is not as simple as they look like, particularly when it comes to implementing a decompiler.
- There are so many times decompilers are used in the IT sector,so we see when actually decompilers play an ethically important role, such as,
- Recovery of lost source code
- Migration of applications to a new hardware platform,
- Determination of the existence of viruses or malicious code in the program
- Recovery of someone else’s source code (to determine an algorithm for example).
The current focus of decompiling is shifting from cracking copy protection to auditing software for exploitable bugs. The same old tricks are being used again, but in a new environment.
Why do we use decompilation ?
Decompilers are used for a number of reasons, some of the applications of it are as follows:
- Debugging of programs can be done by using decompilers.
- By the help of the decompilers, we can determine the existence of viruses or malicious code in the program.
- It can provide interoperability to facilitate migration of a program across platforms.
- Decompilation provides antivirus capability so by the help of it we can find vulnerabilities in the given program.
When can decompilation be used?
There are many situations when decompilation can be used…
- To recover lost source code. You may have written a program for which you only have the executable now (or you got the exe of a program you wrote long back, from someone else!). If you want to have the source for such a program, you can use decompilation to recover it. In all rights, you are the owner of the program, so nobody is going to question you.
- Just as stated above, applications written long back for a legacy computer may not have the source code now, and you may need to port it to a new platform. Either you have to rewrite the application from scratch, or use decompilation to understand the working of the application and write it again.
- Say you have code written in some language for which you can’t find a compiler today! If you have the executable, just decompile it and rewrite the logic in the language of your choice today.
- To discover the internals of someone else’s program (like what algorithm they have used…)
How does decompilation work?
Decompilation follows below mentioned steps:
1. Disassembly — transformation from machine code to the assembly equivalent. There are a surprising number of pitfalls here.
2. Lifting and dataflow analysis — transforming the resulting assembly code into a higher-level internal representation, such as our three-operand assembly. One of the tricky parts here is recognizing distinct variables, and detaching variables from registers or addresses. We also recover expressions, function return values and arguments.
3. Control flow analysis — recovering control flow structure information, such as if and while statements, as well as their nesting level.
4. Type analysis — recovering types of variables, functions, and other pieces of data.
Is decompiler illegal?
Decompiling is both illegal and wrong, unless it’s your own work. You can learn what you need on Google, or find open-source stuff using it and learn from that. It’s illegal to decompile ANYTHING without permission.
Ethics of decompilation :
- Most of the computer programs covered by copyright laws.Although the precise scope of what is covered by copyright differs from region to region, copyright law generally provides the author (the programmer(s) or employer) with a collection of exclusive rights to the program.
- These rights include the right to make copies, including copies made into the computer’s RAM (unless creating such a copy is essential for using the program). Since the decompilation process involves making multiple such copies, it is generally prohibited without the authorization of the copyright holder. However, because decompilation is often a necessary step in achieving software interoperability.
- Different countries have different exceptions to the copyright owner’s rights or precedent has been established in court proceedings. This means that these uses are allowed by law. The most common ones are:
- Decompilation/disassembly for the purposes of interoperability (to another piece of software or hardware) where the interface specification has not been made available.
- Decompilation/disassembly for the purposes of error correction where the owner of the copyright is not available to make the correction,
- To determine parts of the program that are not protected by copyright (e.g. algorithms), without breach of other forms of protection (e.g. patents or trade secrets).
References:
1.https://www.cl.cam.ac.uk/teaching/2000/OptComp/local/ethics.html
2.https://en.wikipedia.org/wiki/Decompiler
3.https://www.debugmode.com/dcompile/
4.https://www.cs.cmu.edu/~fp/courses/15411-f13/lectures/20-decompilation.pdf
5.https://www.techopedia.com/definition/6798/decompiler
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