ENCRYPT(3) Cryptographic Functions ENCRYPT(3)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() func‐
tion sets the key used by encrypt(). The key parameter 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 parameter 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 reen‐
trant 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, 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.)
EXAMPLE
You need to link with libcrypt to compile this example with glibc2.2.
To do useful work the key[] and txt[] arrays must be filled with a use‐
ful bit pattern. Note that the <crypt.h> header unconditionally gives
the prototypes for setkey() and encrypt().
#include <crypt.h>
main() {
char key[64]; /* bit pattern for key */
char txt[64]; /* bit pattern for messages */
setkey(key);
encrypt(txt, 0); /* encode */
encrypt(txt, 1); /* decode */
}
NOTE
In glibc2.2 these functions use the DES algorithm.
CONFORMING TO
The functions encrypt() and setkey() conform to SVr4, SUSv2, and
POSIX.1-2001. The functions encrypt_r() and setkey_r() are GNU exten‐
sions.
SEE ALSOcbc_crypt(3), crypt(3), ecb_crypt(3), fcrypt(3), feature_test_macros(7)glibc2 2003-04-04 ENCRYPT(3)
