SETKEY(3)                  POSIX Programmer's Manual                 SETKEY(3)



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

NAME
       setkey -- set encoding key (CRYPT)

SYNOPSIS
       #include <stdlib.h>

       void setkey(const char *key);

DESCRIPTION
       The setkey() function provides access to an implementation-defined
       encoding algorithm. The argument of setkey() is an array of length 64
       bytes containing only the bytes with numerical value of 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 used by the
       algorithm. This is the key that shall be used with the algorithm to
       encode a string block passed to encrypt().

       The setkey() 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 setkey().  If errno is non-zero on
       return, an error has occurred.

       The setkey() function need not be thread-safe.

RETURN VALUE
       No values are returned.

ERRORS
       The setkey() function shall fail if:

       ENOSYS The functionality is not supported on this implementation.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       Decoding need not be implemented in all environments. This is related
       to government restrictions in some countries on encryption and
       decryption routines. 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
       A future version of the standard may mark this interface as obsolete or
       remove it altogether.

SEE ALSO
       crypt(), encrypt()

       The Base Definitions volume of POSIX.1-2017, <stdlib.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                            SETKEY(3)
