crypt(3C)       UNIX System V(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.

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

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





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crypt(3C)       UNIX System V(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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