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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 int datalen,
unsigned int mode);
int cbc_crypt(char *key, char *data, unsigned int datalen,
unsigned int 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 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 substi‐
tutions 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.
RETURN VALUE
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.
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 cryptography library, such as libgcrypt.
ATTRIBUTES
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 │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘
CONFORMING TO
4.3BSD. Not in POSIX.1.
SEE ALSO
des(1), crypt(3), xcrypt(3)
2021-03-22 DES_CRYPT(3)