COHERENT manpages
This page displays the COHERENT manpage for crypt [Encrypt/decrypt text].
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crypt -- Command Encrypt/decrypt text crypt [password] The command crypt encrypts data. It emulates a rotor-encryption machine, such as the Enigma or Hagelin C-48 cipher machines. Unlike these machines, crypt uses only one rotor, with a 256-character alphabet and a keying sequence of period 2^32. crypt reads text from standard input and writes the encrypted text to standard output. password is used to construct the model of the machine and to start the keying sequence. If no password is given, crypt prompts for a password on the terminal and disables echo while it is being typed in. The password may be up to ten characters long, but must not be empty; all characters past the first ten are ignored. All characters are legal, although it may not be possible to input certain characters from the terminal. crypt uses the same password for both encryption and decryption. For example, the commands crypt COHERENT <file1 >file2 crypt COHERENT <file2 >file3 leave file3 identical to file1. Encrypted files produced by ed with its -x option may be read by crypt, and vice versa, as ed uses crypt to perform its encryption. Security of a cryptosystem depends on several factors: 1. Brute-force attempts to break the system should be infeasible. Passwords should be at least five characters long; although the construction of the machine model from the password takes a substantial fraction of a second, it is still plausible that encrypted files could be read by a brute-force search of a portion of the password space (say, all passwords less than four characters long). 2. Cryptanalysis of the basic encryption scheme should be very hard. Analysis of rotor machines is understood, but it is difficult and in most cases probably not worth the trouble. 3. Passwords must be kept secret. crypt erases password as soon as it can, to avoid the possibility that it could appear in the output of ps. 4. Privileged access to the system must be guarded. Under COHERENT, the security of crypt can be no better than the security governing access to superuser status, because the superuser can do practically anything. This is probably crypt's most vulnerable point. Files /dev/tty -- Typed passwords See Also commands, passwd, security, shadow