* The classic example of cryptographic keys is how Julius Caesar encoded messages to his allies.
Each letter in the message was shifted by three: A became D, B became E, C became F, and so on.
Only someone who knew to shift the letters back by three could decode the messages. Cryptographic
keys work the same way, except they??™re slightly more complicated.
Permissions and Security | 479
Users and
Security
NTFS Encryption Utility
The NTFS Encryption Utility (cipher.exe) lets you encrypt or decrypt
files and manage certificates from the Command Prompt, but it??™s not
included with all editions of Windows. It does have the added benefit of
being able to perform some tricks that the Certificate Manager, just discussed,
cannot.
Open a Command Prompt window (cmd.exe) and type cipher without
any arguments to display the encryption status for all the files in the current
folder. (Use the cd command discussed in Chapter 9 to change to a
different working folder.) Encrypted files will be marked with an E; all
others will marked with a U.
To encrypt a file, type cipher /e filename, where filename is the name of
the file or folder (include the full path if it??™s in a different folder). Likewise,
type cipher /d filename to turn off encryption for the item.
To back up your certificate, type cipher /r:filename at the prompt,
where filename is the prefix of the output filename (without an extension).
Cipher asks for a password, and then generates two separate files
based on the specified filename.
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