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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLE | SEE ALSO | COLOPHON |
ENCRYPT(3) Linux Programmer's Manual ENCRYPT(3)
encrypt, setkey, encrypt_r, setkey_r - encrypt 64-bit messages
#define _XOPEN_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>
void encrypt(char block[64], int edflag);
#define _XOPEN_SOURCE /* See feature_test_macros(7) */
#include <stdlib.h>
void setkey(const char *key);
#define _GNU_SOURCE /* See feature_test_macros(7) */
#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.
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.
These functions do not return any value.
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.)
For an explanation of the terms used in this section, see
attributes(7).
┌────────────────────────┬───────────────┬──────────────────────┐
│Interface │ Attribute │ Value │
├────────────────────────┼───────────────┼──────────────────────┤
│encrypt(), setkey() │ Thread safety │ MT-Unsafe race:crypt │
├────────────────────────┼───────────────┼──────────────────────┤
│encrypt_r(), setkey_r() │ Thread safety │ MT-Safe │
└────────────────────────┴───────────────┴──────────────────────┘
encrypt(), setkey(): POSIX.1-2001, POSIX.1-2008, SUS, SVr4.
The functions encrypt_r() and setkey_r() are GNU extensions.
In glibc 2.2, these functions use the DES algorithm.
#define _XOPEN_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <crypt.h>
int
main(void)
{
char key[64];
char orig[9] = "eggplant";
char buf[64];
char txt[9];
int i, j;
for (i = 0; i < 64; i++) {
key[i] = rand() & 1;
}
for (i = 0; i < 8; i++) {
for (j = 0; j < 8; j++) {
buf[i * 8 + j] = orig[i] >> j & 1;
}
setkey(key);
}
printf("Before encrypting: %s\n", orig);
encrypt(buf, 0);
for (i = 0; i < 8; i++) {
for (j = 0, txt[i] = '\0'; j < 8; j++) {
txt[i] |= buf[i * 8 + j] << j;
}
txt[8] = '\0';
}
printf("After encrypting: %s\n", txt);
encrypt(buf, 1);
for (i = 0; i < 8; i++) {
for (j = 0, txt[i] = '\0'; j < 8; j++) {
txt[i] |= buf[i * 8 + j] << j;
}
txt[8] = '\0';
}
printf("After decrypting: %s\n", txt);
exit(EXIT_SUCCESS);
}
cbc_crypt(3), crypt(3), ecb_crypt(3),
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2015-08-08 ENCRYPT(3)
Pages that refer to this page: crypt(3)