CRYPT(3-BSD)        RISC/os Reference Manual         CRYPT(3-BSD)



NAME
     crypt, setkey, encrypt - DES encryption

SYNOPSIS
     char *crypt(key, salt)
     char *key, *salt;

     setkey(key)
     char *key;

     encrypt(block, edflag)
     char *block;

     cc ... -lcrypt

DESCRIPTION
     NOTE: By default, setkey is not available, and encrypt
     ignores the value of edflag (it is always treated as 0).
     Standard versions of these routines are available in the
     crypt library (/usr/lib/libcrypt.a), which is only available
     in the version of RISC/os distributed in the USA.

     crypt is the password encryption routine.  It is based on
     the NBS Data Encryption Standard, with variations intended
     (among other things) to frustrate use of hardware implemen-
     tations of the DES for key search.

     The first argument to crypt is normally a user's typed pass-
     word.  The second argument, salt, is a 2-character string
     chosen from the set [a-zA-Z0-9./].  The salt is used to per-
     turb the DES algorithm in one of 4096 different ways, after
     which the password is used as the key to encrypt repeatedly
     a constant string.  The returned value points to the
     encrypted password, in the same alphabet as the salt.  The
     first two characters are the salt itself.

     The other entries provide (rather primitive) access to the
     actual DES algorithm.  The argument of setkey is a character
     array of length 64 containing only the characters with
     numerical value 0 and 1.  If this string is divided into
     groups of 8, the low-order bit in each group is ignored,
     leading to a 56-bit key which is set into the machine.

     The argument to the encrypt entry is likewise a character
     array of length 64 containing 0's and 1's.  The argument
     array is modified in place to a similar array representing
     the bits of the argument after having been subjected to the
     DES algorithm using the key set by setkey.  If edflag is 0,
     the argument is encrypted; if non-zero, it is decrypted.

SEE ALSO
     getpass(3), passwd(4).



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CRYPT(3-BSD)        RISC/os Reference Manual         CRYPT(3-BSD)



     login(1), passwd(1) in the User's Reference Manual.

CAVEATS
     The return value points to static data whose content is
     overwritten by each call.


















































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