setkey(1) set encoding key (CRYPT)


#include <stdlib.h>

void setkey(const char *key);


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.


No values are returned.


The setkey() function shall fail if:

The functionality is not supported on this implementation.

The following sections are informative.




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.






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 .