Manpages - encrypt.3
Table of Contents
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NAME
encrypt, setkey, encrypt_r, setkey_r - encrypt 64-bit messages
SYNOPSIS
#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",structcrypt_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 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, errno is unchanged.
- ENOSYS
- The function is not provided. (For example because of former USA export restrictions.)
VERSIONS
Because they employ the DES block cipher, which is no longer considered secure, crypt*(), *crypt_r*(), *setkey*(), and *setkey_r*() were removed in glibc 2.28. Applications should switch to a modern cryptography library, such as *libgcrypt.
ATTRIBUTES
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 |
CONFORMING TO
*encrypt*(), *setkey*(): POSIX.1-2001, POSIX.1-2008, SUS, SVr4.
The functions *encrypt_r*() and *setkey_r*() are GNU extensions.
NOTES
Availability in glibc
See *crypt*(3).
Features in glibc
In glibc 2.2, these functions use the DES algorithm.
EXAMPLES
#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]; for (int i = 0; i < 64; i++) { key[i] = rand() & 1; } for (int i = 0; i < 8; i++) { for (int 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 (int i = 0; i < 8; i++) { for (int 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 (int i = 0; i < 8; i++) { for (int 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); }
SEE ALSO
*cbc_crypt*(3), *crypt*(3), *ecb_crypt*(3),
COLOPHON
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