DES_CRYPT(3) Linux Programmer's Manual DES_CRYPT(3)
NAME
des_crypt, 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 status);
DESCRIPTION
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
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 to-
gether some things. For the encryption direction OR in either DES_EN-
CRYPT 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 hard-
ware, then the encryption is performed in software and the routine re-
turns 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.
RETURN VALUE
DESERR_NONE
No error.
DESERR_NOHWDEVICE
Encryption succeeded, but done in software instead of the re-
quested 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.
VERSIONS
These functions were added to glibc in version 2.1.
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 cryptog-
raphy library, such as libgcrypt.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+--------------------------+---------------+---------+
|Interface | Attribute | Value |
+--------------------------+---------------+---------+
|ecb_crypt(), cbc_crypt(), | Thread safety | MT-Safe |
|des_setparity() | | |
+--------------------------+---------------+---------+
CONFORMING TO
4.3BSD. Not in POSIX.1.
SEE ALSO
des(1), crypt(3), xcrypt(3)
COLOPHON
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description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2020-04-11 DES_CRYPT(3)