| Why using Cryptosystem ME6 is safer than using other encryption software |
When using encryption software there is always the possibility that a mistake in its use will lead to irrecoverability of the encrypted data and thus its loss (unless there is a backup of the plaintext somewhere). Cryptosystem ME6 has several features which are there to minimize the likelihood of making a mistake when using the software. Some possible mistakes, and ME6's attempt to help you avoid them, are as follows:
1. Encrypting when you think you're decrypting or vice-versa
Unless the user interface makes it quite clear which operation you are performing, you might accidentally doube-encrypt your data or attempt to decrypt data which is not encrypted. ME6's display shows clearly which operation is being performed.
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Before the operation is carried out you are presented with a brief description of the operation to be performed and are asked to confirm.
Cryptosystem ME6 checks the randomness measure of each file being decrypted. If this value is less than about 0.9, indicating that the file is not encrypted, then ME6 displays a warning message:
2. Using an encryption key which is slightly different to what you think you are using
The main preventive measure is the association of a 4-digit number, the "checksum", with the encryption key being used. This is displayed as you type the encryption (or decryption) key. If you use just one encryption key then the checksum is easily remembered and is always the same. If you make a mistake in typing just one character then the checksum will be a completely different 4-digit number, and you will be alerted to your mistake before performing the operation.
3. Setting up an operation improperly
If you have a complex operation which you perform on a regular basis, e.g. encrypting files with a particular file extension in a folder and in all subfolders, then you could sometime make a mistake in setting the operation up (e.g., forget to specify that subfolders are to be included). ME6 overcomes this problem by allowing you to define a "setup" (specifying the operation to be performed) which can be saved and loaded. This not only helps avoid mistakes but saves time, which is useful at the end of the workday when you want to encrypt your files and get out of the office quickly.
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For more information about saving and loading setup files see Section 4.11 and Section 4.12 of the User Manual.
4. Encrypting files which are already encrypted or attempting to decrypt files which are not encrypted
With most other encryption software you may sometimes be unsure as to whether you have actually encrypted a set of files. This makes it easy to make a mistake by encrypting files which you think are not encrypted but which you have already encrypted. Then when you decrypt those files you will recover, not the plaintext which you were expecting, but the result of the first encryption. These files will appear to contain garbage, and it would be easy to conclude that the decryption operation has not worked properly. In this case the plaintext can be obtained simply by performing an additional decryption, but if you don't know this then you may conclude that your data has been lost.
Another problem arises if you think you have encrypted a set of files, which in fact are not encrypted, and you attempt to decrypt them. In most cases Cryptosystem ME6 will detect this error, but occasionally it will perform the "decryption" on the plaintext, and the result will not be the plaintext. In this case the plaintext can be recovered by performing an encryption, if you are aware of this possibility.
Both of these possible sources of error are countered in ME6 by the ability to test a file or a set of files for randomness, using the "Randomness test". Encrypted files typically have a randomness measure greater than 0.9, whereas that for unencrypted files is seldom more than 0.5. Thus, before performing an operaton, you can always ascertain whether a set of files contains plaintext or ciphertext by running a randomness test. This should always be done before you decrypt files, just to make sure that you have previously encrypted them (not just that you seem to remember that you encrypted them).
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For more information about the randomness report in Cryptosystem ME6 see Section 4.10 of the User Manual.
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