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

     CAVEAT
          The return value points to static data that are overwritten



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     CRYPT(3C)                                               CRYPT(3C)



          by each call.

     ORIGIN
          AT&T V.3



















































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