DES_CRYPT(3) Linux Programmers Manual DES_CRYPT(3)
des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED - fast DES
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 avail
able. 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
Here is how to use these routines. The first argument, key, is the
8-byte encryption key with parity. To set the keys 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 OR ing
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 routines are present in libc 4.6.27 and later, and in glibc 2.1
4.3BSD. Not in POSIX.1-2001.
des(1), crypt(3), xcrypt(3)
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