Ubuntu Manpage: des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED

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 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 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.

COLOPHON

       This  page  is  part of release 5.13 of the Linux man-pages project.  A 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/.

                                            2021-03-22                               DES_CRYPT(3)