CRYPT(1) CRYPT(1)
NAME
crypt, encrypt, decrypt - encode/decode
SYNOPSIS
/usr/games/crypt [ password ]
/usr/games/encrypt [ -p ] [ password ]
/usr/games/decrypt [ -p ] [ password ]
DESCRIPTION
These commands read from the standard input and write on the
standard output. The password is an enciphering key. If no
password is given, one is demanded from the terminal; echo-
ing is turned off while it is being typed in. Crypt uses a
relatively simple, fast method (rotor machine) for both
enciphering and deciphering. Encrypt and decrypt use a more
robust, slower method (DES). Files enciphered by crypt are
not intelligible to encrypt/decrypt, and vice versa.
It is prudent to supply the key from the terminal, not from
the command line, and to pick a reasonably obscure and long
key (6 letters for crypt and much longer for encrypt).
Under option -p encrypt enciphers into printing characters,
which can be sent by mail(1). Decrypt can distinguish
ciphertext from clear: it will work on a full mail message,
headers and all.
FILES
for typed key
SEE ALSO
ed(1), makekey(8)
J. A. Reeds and P. J. Weinberger, `File Security and the
Unix Crypt Command,' AT&T Bell Laboratories Technical
Journal, 63 (1984) 1673-1684
BUGS
Crypt is breakable by knowledgeable cryptanalysts. Its only
practical use is for mildly private data transmission.
Encrypt/decrypt gives strong protection for transmission
over untrusted channels between trusted machines.
It is unwise to count on encryption of any sort for safe
storage of documents.