centos man page for encrypt

ENCRYPT(3P)						     POSIX Programmer's Manual						       ENCRYPT(3P)

PROLOG
       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
       encrypt - encoding function (CRYPT)

SYNOPSIS
       #include <unistd.h>

       void encrypt(char block[64], int edflag);

DESCRIPTION
       The encrypt() function shall provide access to an implementation-defined encoding algorithm. The key  generated	by  setkey()  is  used	to
       encrypt the string block with encrypt().

       The  block  argument to encrypt() shall be an array of length 64 bytes containing only the bytes with values of 0 and 1. The array is modi-
       fied in place to a similar array using the key set by setkey(). If edflag is 0, the argument is encoded.  If edflag is 1, the argument  may
       be decoded (see the APPLICATION USAGE section); if the argument is not decoded, errno shall be set to [ENOSYS].

       The encrypt() function shall not change the setting of errno if successful. An application wishing to check for error situations should set
       errno to 0 before calling encrypt().  If errno is non-zero on return, an error has occurred.

       The encrypt() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

RETURN VALUE
       The encrypt() function shall not return a value.

ERRORS
       The encrypt() function shall fail if:

       ENOSYS The functionality is not supported on this implementation.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       Historical implementations of the encrypt() function used a rather primitive encoding algorithm.

       In some environments, decoding might not be implemented. This is related to some Government restrictions on encryption and decryption  rou-
       tines.  Historical  practice  has been to ship a different version of the encryption library without the decryption feature in the routines
       supplied. Thus the exported version of encrypt() does encoding but not decoding.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       crypt(), setkey(), the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       ENCRYPT(3P)