#`CLIPSP.SYS` Decryption

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peak lichen
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For context, CLIPSP.SYS is the Windows kernel driver used in licensing and genuine activation. Like some other Windows kernel drivers, it uses Warbird encryption; however, CLIPSP.SYS is special with regards to its encryption because it implements a copy of FeistelDecrypt inside itself. Using various techniques and a little outside help, I was able to emulate a kernel-mode environment in user-mode and call the necessary functions for decryption, saving the decrypted memory to disk.