#include <stdlib.h> void setkey(const char *key);
The setkey() function provides (rather primitive) access to the hashing algorithm employed by the crypt(3C) function. 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 will be used with the algorithm to encode a string block passed to encrypt(3C).
No values are returned.
The setkey() function will fail if:
The functionality is not supported on this implementation.
In some environments, decoding may not be implemented. This is related to U.S. Government restrictions on encryption and decryption routines: the DES decryption algorithm cannot be exported outside the U.S.A. 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.
Because setkey() does not return a value, applications wishing to check for errors should set errno to 0, call setkey(), then test errno and, if it is non-zero, assume an error has occurred.
See attributes(5) for descriptions of the following attributes: