ecb_crypt

, cbc_crypt

, des_setparity

, DES_FAILED

- fast DES encryption

Synopsis

#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 stat);

Description

ecb_crypt() and cbc_crypt() implement the NBS DES (Data Encryption Standard). These routines are faster and more general purpose than crypt(3C). 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.

The first parameter, 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 parameter, data, contains the data to be encrypted or decrypted. The third parameter, datalen, is the length in bytes of data, which must be a multiple of 8. The fourth parameter, mode, is formed by OR'ing together the DES_ENCRYPT or DES_DECRYPT to specify the encryption direction and DES_HW or DES_SW to specify software or hardware encryption. 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 parameter ivec is the 8-byte initialization vector for the chaining. It is updated to the next initialization vector upon successful return.

Return Values

Given a result status stat, the macro DES_FAILED is false only for the first two statuses.

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 parameter to routine.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

crypt(3C), attributes(5)

Notes

When compiling multi-thread applications, the _REENTRANT flag must be defined on the compile line. This flag should only be used in multi-thread applications.