NAME
encrypt, setkey, encrypt_r, setkey_r - encrypt 64-bit messages
SYNOPSIS
#define _XOPEN_SOURCE
#include <unistd.h>
void encrypt(char block[64], int edflag);
#define _XOPEN_SOURCE
#include <stdlib.h>
void setkey(const char *key);
#define _GNU_SOURCE
#include <crypt.h>
void setkey_r(const char *key, struct crypt_data *data);
void encrypt_r(char *block, int edflag, struct crypt_data *data);
Each of these requires linking with -lcrypt.
DESCRIPTION
These functions encrypt and decrypt 64-bit messages. The setkey()
function sets the key used by encrypt(). The key argument used here is
an array of 64 bytes, each of which has numerical value 1 or 0. The
bytes key[n] where n=8*i-1 are ignored, so that the effective key
length is 56 bits.
The encrypt() function modifies the passed buffer, encoding if edflag
is 0, and decoding if 1 is being passed. Like the key argument, also
block is a bit vector representation of the actual value that is
encoded. The result is returned in that same vector.
These two functions are not reentrant, that is, the key data is kept in
static storage. The functions setkey_r() and encrypt_r() are the
reentrant versions. They use the following structure to hold the key
data:
struct crypt_data {
char keysched[16 * 8];
char sb0[32768];
char sb1[32768];
char sb2[32768];
char sb3[32768];
char crypt_3_buf[14];
char current_salt[2];
long int current_saltbits;
int direction;
int initialized;
};
Before calling setkey_r() set data->initialized to zero.
RETURN VALUE
These functions do not return any value.
ERRORS
Set errno to zero before calling the above functions. On success, it
is unchanged.
ENOSYS The function is not provided. (For example because of former
USA export restrictions.)
CONFORMING TO
The functions encrypt() and setkey() conform to SVr4, SUSv2, and
POSIX.1-2001. The functions encrypt_r() and setkey_r() are GNU
extensions.
NOTES
In glibc 2.2 these functions use the DES algorithm.
EXAMPLE
You need to link with libcrypt to compile this example with glibc. To
do useful work the key[] and txt[] arrays must be filled with a useful
bit pattern.
#define _XOPEN_SOURCE
#include <unistd.h>
#include <stdlib.h>
int
main(void)
{
char key[64]; /* bit pattern for key */
char txt[64]; /* bit pattern for messages */
setkey(key);
encrypt(txt, 0); /* encode */
encrypt(txt, 1); /* decode */
}
SEE ALSO
cbc_crypt(3), crypt(3), ecb_crypt(3), feature_test_macros(7)
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2003-04-04