CRYPT(3C-SVR4)      RISC/os Reference Manual       CRYPT(3C-SVR4)



NAME
     crypt, setkey, encrypt - generate encryption

SYNOPSIS
     #include <crypt.h>

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

     void setkey (const char *key);

     void encrypt (char *block, int edflag);

DESCRIPTION
     crypt is the password encryption function.  It is based on a
     one-way encryption algorithm with variations intended (among
     other things) to frustrate use of hardware implementations
     of a key search.

     key is the input string to encrypt, for instance, a user's
     typed password.  Only the first eight characters are used;
     the rest are ignored.  salt is a two-character string chosen
     from the set "a-zA-Z0-9./" ; this string is used to perturb
     the hashing algorithm in one of 4096 different ways, after
     which the input string is used as the key to encrypt repeat-
     edly a constant string.  The returned value points to the
     encrypted input string.  The first two characters of the
     return value are the salt itself.

     The setkey and encrypt functions provide (rather primitive)
     access to the actual hashing algorithm.  The argument of
     setkey is a character array of length 64 containing only the
     characters with numerical value 0 and 1.  This string is
     divided into groups of 8, the low-order bit in each group is
     ignored; this gives a 56-bit key that is set into the
     machine.  This is the key that will be used with the hashing
     algorithm to encrypt the string block with the encrypt func-
     tion.

     The block argument of encrypt is a character array of length
     64 containing only the characters with numerical value 0 and
     1.  The argument array is modified in place to a similar
     array representing the bits of the argument after having
     been subjected to the hashing algorithm using the key set by
     setkey.  The argument edflag, indicating decryption rather
     than encryption, is ignored; use encrypt in libcrypt [see
     crypt(3X)] for decryption.

SEE ALSO
     getpass(3C), crypt(3X), passwd(4).
     login(1), passwd(1) in the User's Reference Manual.





                        Printed 11/19/92                   Page 1

CRYPT(3C-SVR4)      RISC/os Reference Manual       CRYPT(3C-SVR4)



DIAGNOSTICS
     If edflag is set to anything other than zero, errno will be
     set to ENOSYS.

NOTES
     The return value for crypt points to static data that are
     overwritten by each call.
















































 Page 2                 Printed 11/19/92