The popular source-availablefreeware program TrueCrypt was based on E4M's source code. However, TrueCrypt uses a different container format than E4M, which makes it impossible to use one of these programs to access an encrypted volume created by the other.
Shortly after TrueCrypt version 1.0 was released in February 2004, the TrueCrypt Team reported receiving emails from Wilfried Hafner, manager of SecurStar, claiming that Paul Le Roux had stolen the source code of E4M from SecurStar as an employee. According to the TrueCrypt Team, the emails stated that Le Roux illegally distributed E4M, and authored an illegal license permitting anyone to base derivative work on E4M and distribute it freely, which Hefner alleges Le Roux did not have any right to do, claiming that all versions of E4M always belonged only to SecurStar. For a time, this led the TrueCrypt Team to stop developing and distributing TrueCrypt.