bitcookies/winrar-keygen: how the rarreg.key license file is generated

What bitcookies/winrar-keygen actually solves

WinRAR is trialware. The README says so directly, and it points anyone who wants to keep using it to rarlab.com, where a purchase produces a licence file named rarreg.key. That file is the subject of this repository. The project does not exist to hand you a key. It exists to explain how the key is built, and to provide a C++ implementation of that construction that you can read, build and inspect.

The audience is narrow and fairly specific. You need to be comfortable with C++ and with the arithmetic behind public key cryptography, because the top-level files include BigInteger.hpp, EllipticCurveGF2m.hpp and GaloisField.hpp. If those names mean nothing to you, the repository will read as a wall of headers. There is also a WPF-based GUI for Windows, which lowers the barrier for generating a file, but the GUI does not explain anything the README does not already explain.

The project is MIT licensed and the last push was on 2026-08-07. Releases have been reasonably frequent through 2026, with v4.1.0 in April, v4.2.0 in June and v4.3.0 in July. That cadence suggests the author is still responding to changes in WinRAR itself, which matters because a key format that drifts would break every build here.

The mechanism: elliptic curve arithmetic over GF(2^m)

The README delegates the full explanation to a separate document, README.HOW_DOES_IT_WORK.md, and keeps only a pointer in the main file. What the repository layout tells you is the shape of the implementation. There is a big integer layer, a Galois field layer, an elliptic curve layer defined over a binary field, and a hashing layer with separate traits for CRC32 and SHA-1.

That combination is the classic structure of an ECDSA-style signature scheme adapted to binary field curves. The Hasher.hpp header plus HasherCrc32Traits.hpp and HasherSha1Traits.hpp suggests the digest step is parameterised, so the same hashing interface is reused with different algorithms. WinRarConfig.hpp and WinRarKeygen.hpp sit above the arithmetic and hold the WinRAR-specific constants and the entry point for producing the file. _tmain.cpp is the console entry point.

A second document, README.VERIFY_Point_G.md, is worth noting. The name indicates it covers verification of the base point G on the curve. Publishing that separately is a reasonable sign: the generator point is the piece most likely to be transcribed incorrectly, and an error there would produce keys that look plausible but fail validation. If you intend to read the code rather than just run it, start with that document.

Building it with CMake and generating a first key

The README lists several routes: GitHub Actions, GitHub Actions with secrets, Visual Studio, CMake, and a Windows GUI. The CMake path is the one that does not depend on a Microsoft toolchain. The repository carries a vcpkg.json manifest, so dependencies are declared rather than documented by hand, and CMakeLists.txt is at the top level.

The README does not print the configure and build commands, so there is no command line to copy from it. What it does give is the project's own build file, CMakeLists.txt, and the vcpkg.json manifest that declares the dependencies. Read both before you configure anything, because the README does not pin a minimum CMake version or name the output binary.

Encoding is the first real decision. The README notes that the default is utf8, and that ascii and ansi are also accepted. The table in section 3.1 spells out the consequence: ascii supports only full ASCII characters, ansi is usually Windows-1252 but can be another local code page, and utf8 supports UTF-8 without BOM across a long list of scripts including Chinese, Japanese, Korean, Greek and Cyrillic. If the name on your licence contains characters outside ASCII, choosing ascii will not preserve them.

Once you have rarreg.key, the README gives the import location as a Windows path, and notes the alternative of compressing the file into rarkey.rar and double-clicking it for automatic import:

%APPDATA%\WinRAR\rarreg.key

Drag-and-drop onto WinRAR also works according to the README. The two licence types, rarreg.key and rarkey.rar, differ only in how they are imported, not in what they contain.

Running it from GitHub Actions without a local toolchain

The Actions route is the one the README leads with, and it is the least demanding on your machine. You fork the repository, open the Actions tab in your fork to allow workflows to run, then go to Actions > WinRAR Keygen > Run workflow and fill in the fields. The workflow is defined in .github/workflows/keygen.yml and is badged in the README.

When the run finishes, you open the completed job and download the rarreg_file artifact, which the README says is retained for 90 days. Extracting it gives you rarreg.key. The README warns that your username and licence name will appear in the Actions log, which is a real exposure if the fork is public. Section 5 of the README covers the alternative: using encrypted secrets so that the values are not printed in the log. If you care about the name not being visible, that is the route to take, not the plain workflow.

The trade-off is that you are trusting GitHub's runners and your own fork's configuration. The workflow only runs in your fork after you explicitly enable it, which is a deliberate step rather than an accident. That is sensible default behaviour, but it also means a fresh fork appears broken until you click through the Actions tab.

Where this project is the wrong tool

The most important limitation is stated by the project itself. WinRAR is not free software. The README says that if you want to use it, you should pay RARLAB, and that doing so is what produces the licence file. Nothing in this repository changes that obligation, and the MIT licence on the code here does not extend to WinRAR or to the licence you would need to run it legally beyond the trial period.

There is a second limitation that is easy to miss. The README does not document rollback, revocation or what happens when a generated file is rejected. If WinRAR changes its validation in a future release, the failure mode is a key that imports without complaint but does not register the product, and the repository gives you no procedure for diagnosing that. The release history suggests the author tracks WinRAR versions, but tracking is not the same as a guarantee.

Finally, this is not an archiver, not a library you would link into an unrelated product, and not a general-purpose crypto toolkit. The elliptic curve code is written for one specific format. Reusing GaloisField.hpp or EllipticCurveGF2m.hpp elsewhere means auditing code that was never presented as a general implementation. If you need elliptic curve primitives in C++, there are libraries built for that purpose with test suites and review history behind them.

The honest alternative: buy the licence

The real alternative is not another keygen. It is the purchase route the README itself recommends. Paying RARLAB gives you a rarreg.key that is issued rather than constructed, and it removes the entire question of whether the format has drifted. You also get support and updates tied to your licence, which no local build can provide.

If the interest is educational rather than practical, the alternative is a general cryptography library or a textbook implementation of ECDSA over binary fields. Those exist to teach the mathematics and come with test vectors. This repository exists to explain one specific product's licence format, and its documentation is organised around that goal. The README.HOW_DOES_IT_WORK.md and README.VERIFY_Point_G.md files are the parts worth reading if that is what you came for.

For the narrower question of extracting archives, WinRAR is not the only option, and the README does not claim otherwise. It describes WinRAR as able to create and view RAR or ZIP archives and unpack numerous formats. If you only need to unpack, the licence question may not arise for you at all, which makes this repository irrelevant to your problem rather than useful to it.

Licence, maintenance and the cost of keeping up

The code is MIT licensed, which permits use, modification and redistribution with the licence text retained. That is a permissive grant over the source in this repository only. It says nothing about WinRAR, about the rarreg.key format, or about whether generating a key for a product you have not paid for is permissible where you live. This article is not legal advice and the licence file in the repository is the authority, not this paragraph.

Maintenance cost is the part worth weighing before you build. The last push was on 2026-08-07, and three releases landed between April and July 2026. That is a project that moves in response to something external, and the something external is WinRAR. If you fork and modify the code, you own the job of rebasing onto those releases. The vcpkg manifest means dependency resolution is reproducible, but it also means a manifest bump can be the thing that breaks your build rather than a change in the key logic.

The GitHub Actions route shifts that cost onto the workflow file. You do not maintain a toolchain, but you do inherit whatever the workflow pins, and the README does not describe a versioning policy for it. If reproducibility matters to you, the CMake path with a committed vcpkg baseline is the more controlled option, at the price of building locally.

Editorial conclusion

Read this repository if you want to understand how the rarreg.key licence file is constructed, or if you are studying the elliptic curve and SHA-1 code it contains. Do not treat it as a way to avoid paying RARLAB: the README states plainly that WinRAR is not free software and points to rarlab.com for a licence. Before building anything, read README.HOW_DOES_IT_WORK.md and README.VERIFY_Point_G.md, then check vcpkg.json and CMakeLists.txt for the dependencies your toolchain will need to resolve.

Frequently asked questions

Official sources

1. bitcookies/winrar-keygen on GitHub
2. Issues
3. License: MIT
4. README
5. Releases