Man Cbc_crypt en anglais
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 

       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 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.

 

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 routines are present in libc 4.6.27 and later, and in  glibc  2.1
       and later.

 

CONFORMING TO


       4.3BSD.  Not in POSIX.1-2001.

 

SEE ALSO


       des(1), crypt(3), xcrypt(3)

 

COLOPHON


       This  page  is  part of release 3.05 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



                                  2007-05-18                      DES_CRYPT(3)