DLOCK2 is a simple command line file encryption/decryption utility program that uses the free Diamond 2 Encryption Algorithm. Full source code and documentation of the algorithm and the master's thesis it is based on are included. It compiles with Gnu C++ and other compilers, so it can be adapted to many operating systems. Version 2.01 is the same as the original DLOCK2, except recompiled for the Win32 command line (for long filename support) and author contact information has been updated. The encryption key may be a passphrase on the command line or it may be contained in a file. You may use the included encryption/decryption source code in your own products at no charge. This software is free, however you may send the author donations to express appreciation if you like.