CRYPT(3C)            INTERACTIVE UNIX System            CRYPT(3C)



          NAME
               crypt, setkey, encrypt - generate hashing encryption

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

               void setkey (key)
               char *key;

               void encrypt (block, ignored)
               char *block;
               int ignored;

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

               Key is a user's typed password.  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 dif-
               ferent ways, after which the password is used as the key to
               encrypt repeatedly a constant string.  The returned value
               points to the encrypted password.  The first two characters
               are the salt itself.

               The setkey and encrypt entries 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.  If this string is
               divided into groups of 8, the low-order bit in each group is
               ignored; this gives a 56-bit key which is set into the
               machine.  This is the key that will be used with the hashing
               algorithm to encrypt the string block with the function
               encrypt.

               The argument to the encrypt entry 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.  Ignored is unused by encrypt but it must be
               present.

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

          CAVEAT
               The return value points to static data that are overwritten


          Rev. C Software Development Set                            Page 1

          CRYPT(3C)            INTERACTIVE UNIX System            CRYPT(3C)



               by each call.






















































          Rev. C Software Development Set                            Page 2