des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED - fast DES encryption
int ecb_crypt(char *key, char *data, unsigned datalen,
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
- No error.
- Encryption succeeded, but done in software instead of the requested
- An error occurred in the hardware or driver.
- Bad argument to routine.
Given a result status stat, the macro
DES_FAILED(stat) is false only for the first two
These functions are present in glibc 2.1 and later.
For an explanation of the terms used in this section, see attributes(7).
|ecb_crypt (), cbc_crypt (), des_setparity ()
4.3BSD. Not in POSIX.1.
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