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Developer delves into Denuvo DRM to run Hogwarts Legacy on a secondary PC

Hardcore DRM: Denuvo is an effective anti-tamper and DRM toolkit that many studios choose to protect their freshly developed games. The controversial technology is notoriously difficult to bypass or defeat, but one lone developer decided to undertake the challenge to understand how it functions under the hood.

DRM developer and reverse engineering expert Maurice Heumann decided to investigate the Denuvo DRM protection embedded in Hogwarts Legacy, the popular action RPG based on the Harry Potter saga, released in 2023 for PC and consoles. The developer dedicated five months of his life to reverse engineering the system in the Avalanche Software-developed game.

Heumann’s goal was not to “crack” Hogwarts Legacy on PC, a task already accomplished by the notorious cracker Empress. Instead, he aimed to analyze Denuvo’s inner workings, prompted by his previous research on an “integrity bypass” for Black Ops 3. While Empress managed to crack and seemingly remove Denuvo from Hogwarts Legacy in just a few days, Heumann encountered greater challenges and achieved a less-than-perfect result in the end.

Heumann explained that the DRM technology is designed to collect hardware and software “features” from a user’s system to create a unique fingerprint and generate a “Steam Ticket.” Both the fingerprint and tickets are then sent back to Denuvo’s server, while the Steam Ticket is forwarded to Steam to verify that the user legitimately purchased the game through Valve’s digital marketplace.

After ownership is confirmed, a “Denuvo Token” is generated, which can only function on the PC where the original fingerprint was created. This Denuvo Token is the data piece that the DRM technology utilizes to decrypt and execute the game on the user’s PC. Hogwarts Legacy cannot operate without a Token, and Denuvo regularly verifies the fingerprint against the system’s hardware to ensure it still matches.

Heumann spent considerable time attempting to identify all the features the game uses to create the fingerprint and then try to patch them out. He managed to pinpoint the most prominent ones with the help of Qiling, a powerful yet buggy “reverse engineering framework” designed to emulate various types of binary files. The developer created approximately 2,000 patches and hooks using the fingerprint generated by Denuvo for his PC. Ultimately, he succeeded in launching and partially loading Hogwarts Legacy on a secondary PC (a laptop) using a token generated for a different PC.

Heumann mentioned that he could continue trying to find all the runtime checks to completely defeat Denuvo, but he felt content with simply launching the game on a non-authenticated system.

He expressed his “utmost respect” for individuals like Empress, who dedicate enough time and motivation to remove Denuvo from any game. Additionally, the developer discovered that the technology does not seem to significantly impact a game’s overall performance, confirming what the DRM developer stated in 2023.

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