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 reentrant. A function that
is not required to be reentrant is not required to 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
None.
SEE ALSO
crypt() , encrypt() , the Base Definitions volume of
IEEE Std 1003.1-2001, <stdlib.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- 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 .