CRYPT(3)                 DOMAIN/IX SYS5                  CRYPT(3)



NAME
     crypt, encrypt - a one-way hashing encryption algorithm

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

     void encrypt(block)
     char *block;


DESCRIPTION
     The password encryption function, crypt, is based on a one-
     way hashing encryption algorithm with variations partly
     intended to frustrate hardware implementations of a key
     search.

     The key parameter represents a user's typed password.  The
     salt parameter 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
     password is used as the key to encrypt repeatedly a constant
     string.  The returned value points to the encrypted pass-
     word.  The first two characters are the salt itself.

     The encrypt entry provides rather primitive access to the
     actual hashing algorithm.  The argument to the encrypt entry
     is a character array of length 64 containing only the char-
     acters with numerical value 0 and 1.  The argument array is
     modified in place, becoming a similar array that represents
     the bits of the argument after exposure to the hashing algo-
     rithm using the key set by crypt.

     Note:
          Per international agreement not to export encryption
          devices, the standard UNIX system decryption methods
          are not supported on the DOMAIN/IX system.

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

RELATED INFORMATION
     login(1), passwd(1), getpass(3C), passwd(4)









Printed 12/4/86                                           CRYPT-1