crypt(3C)           (C Programming Language Utilities)            crypt(3C)


   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 repeatedly 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
         function.

         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.

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

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



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   crypt(3C)           (C Programming Language Utilities)            crypt(3C)


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


















































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