DiskCryptor is the only truly free solution, provided under GNU General Public License (GPLv3), which offers encryption of all disk partitions, including the system partition. The main criteria for open-source software is the availability of its source code under one of the open source licenses. The only open-source alternative to DiskCryptor that has comparable features is TrueCrypt. However, because of the restrictive license under which TrueCrypt is provided — the TrueCrypt Collective License — TrueCrypt cannot be classified as a truly free software, as it places limits on the use and modification of its source code by developers. There are other alternatives with similar functionality, but they are fully proprietary ones, which makes them unacceptable to use for protection of confidential data.
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