des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED - fast DES encryption
#include <rpc/des_crypt.h>
int ecb_crypt(char *key, char *data, unsigned datalen,
unsigned mode);
int cbc_crypt(char *key, char *data, unsigned datalen,
unsigned mode, char *ivec);
void des_setparity(char *key);
int DES_FAILED(int status);
ecb_crypt() and
cbc_crypt() implement the NBS DES (Data Encryption
Standard). These routines are faster and more general purpose than
crypt(3). They also are able to utilize DES hardware if it is
available.
ecb_crypt() encrypts in ECB (Electronic Code Book) mode,
which encrypts blocks of data independently.
cbc_crypt() encrypts in
CBC (Cipher Block Chaining) mode, which chains together successive blocks. CBC
mode protects against insertions, deletions and substitutions of blocks. Also,
regularities in the clear text will not appear in the cipher text.
Here is how to use these routines. The first argument,
key, is the 8-byte
encryption key with parity. To set the key's parity, which for DES is in the
low bit of each byte, use
des_setparity(). The second argument,
data, contains the data to be encrypted or decrypted. The third
argument,
datalen, is the length in bytes of
data, which must be
a multiple of 8. The fourth argument,
mode, is formed by ORing together
some things. For the encryption direction OR in either
DES_ENCRYPT or
DES_DECRYPT. For software versus hardware encryption, OR in either
DES_HW or
DES_SW. If
DES_HW is specified, and there is no
hardware, then the encryption is performed in software and the routine returns
DESERR_NOHWDEVICE. For
cbc_crypt(), the argument
ivec is
the 8-byte initialization vector for the chaining. It is updated to the next
initialization vector upon return.
- DESERR_NONE
- No error.
- DESERR_NOHWDEVICE
- Encryption succeeded, but done in software instead of the requested
hardware.
- DESERR_HWERROR
- An error occurred in the hardware or driver.
- DESERR_BADPARAM
- Bad argument to routine.
Given a result status
stat, the macro
DES_FAILED(stat) is false only for the first two
statuses.
These functions are present in glibc 2.1 and later.
Because they employ the DES block cipher, which is no longer considered secure,
ecb_crypt(),
ecb_crypt(),
crypt_r(), and
des_setparity() were removed in glibc 2.28. Applications should switch
to a modern cryptography library, such as
libgcrypt.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| ecb_crypt (), cbc_crypt (), des_setparity () |
Thread safety |
MT-Safe |
4.3BSD. Not in POSIX.1.
des(1),
crypt(3),
xcrypt(3)