Reverse engineering 1990s legacy enterprise software licensing

This article explores a software licensing system used in a proprietary enterprise software package from circa 1994, which is no longer supported by the original developers. The licensing system operated on the basis of short alphanumeric licence keys issued to licensees (e.g. ABCD 012345 67890). The software is distributed as a binary executable (say, foo.exe ) and accompanied by a number of…