Cryptosystem ME6 is a Windows program which uses a symmetric key encryption system to encrypt information in either a single file or in multiple files (at once) so that it cannot be read by those not knowing the key. Data is encrypted using a key which is from 16 to 64 characters long, and which can be either a phrase or a sequence of 64 random bytes (the software provides a way for you to generate such random keys). Without the key the encrypted data is unintelligible and the information cannot be read. If your files are encrypted using ME6 then you can sleep easily at night knowing that even if they are stolen the thief will obtain no information. The size, the type and the number of files which can be encrypted in a single operation is limited only by disk space. You can select a single file to be encrypted (or decrypted) by means of the usual Windows file selection dialog box. Multiple files can be selected by using wildcards, e.g., *.txt to encrypt all files with txt suffix. You also specify whether you want to overwrite the original files with their encrypted (or decrypted) versions or to produce encrypted (or decrypted) files with different names. Files are normally compressed before encryption (which also makes cryptanalysis more difficult). There are various options at the main menu which allow you to customize the operation of the program. For example, you can request the program to operate on files not only in a specified folder but also in all lower folders (this is useful for encrypting an entire project which has files in subfolders). After you have specified the conditions of the encryption or decryption operation and instructed the program to perform the operation the conditions are checked and any errors or exceptional conditions (such as the non-existence of the specified input files or lack of space on the output disk) are reported.