'\" t
.\" @(#)des_crypt.3	2.1 88/08/11 4.0 RPCSRC; from 1.16 88/03/02 SMI;
.\"
.\" Taken from libc4 sources, which say:
.\" Copyright (C) 1993 Eric Young - can be distributed under GPL.
.\"
.\" However, the above header line suggests that this file in fact is
.\" Copyright Sun Microsystems, Inc (and is provided for unrestricted use,
.\" see other Sun RPC sources).
.\"
.\" SPDX-License-Identifier: GPL-1.0-or-later
.\"
.TH des_crypt 3 2023-10-31 "Linux man-pages 6.06"
.SH NAME
des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED \- fast
DES encryption
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.\" Sun version
.\" .B #include <des_crypt.h>
.B #include <rpc/des_crypt.h>
.P
.BI "[[deprecated]] int ecb_crypt(char *" key ", char " data [. datalen ],
.BI "                             unsigned int " datalen ", \
unsigned int " mode );
.BI "[[deprecated]] int cbc_crypt(char *" key ", char " data [. datalen ],
.BI "                             unsigned int " datalen ", \
unsigned int " mode ,
.BI "                             char *" ivec );
.P
.BI "[[deprecated]] void des_setparity(char *" key );
.P
.BI "[[deprecated]] int DES_FAILED(int " status );
.fi
.SH DESCRIPTION
.BR ecb_crypt ()
and
.BR cbc_crypt ()
implement the
NBS
DES
(Data Encryption Standard).
These routines are faster and more general purpose than
.BR crypt (3).
They also are able to utilize
DES
hardware if it is available.
.BR ecb_crypt ()
encrypts in
ECB
(Electronic Code Book)
mode, which encrypts blocks of data independently.
.BR 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.
.P
Here is how to use these routines.
The first argument,
.IR 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
.BR des_setparity ().
The second argument,
.IR data ,
contains the data to be encrypted or decrypted.
The
third argument,
.IR datalen ,
is the length in bytes of
.IR data ,
which must be a multiple of 8.
The fourth argument,
.IR mode ,
is formed by ORing together some things.
For the encryption direction OR in either
.B DES_ENCRYPT
or
.BR DES_DECRYPT .
For software versus hardware
encryption, OR in either
.B DES_HW
or
.BR DES_SW .
If
.B DES_HW
is specified, and there is no hardware, then the encryption is performed
in software and the routine returns
.BR DESERR_NOHWDEVICE .
For
.BR cbc_crypt (),
the argument
.I ivec
is the 8-byte initialization
vector for the chaining.
It is updated to the next initialization
vector upon return.
.SH RETURN VALUE
.TP
.B DESERR_NONE
No error.
.TP
.B DESERR_NOHWDEVICE
Encryption succeeded, but done in software instead of the requested hardware.
.TP
.B DESERR_HWERROR
An error occurred in the hardware or driver.
.TP
.B DESERR_BADPARAM
Bad argument to routine.
.P
Given a result status
.IR stat ,
the macro
.\" .BR DES_FAILED\c
.\" .BR ( stat )
.BI DES_FAILED( stat )
is false only for the first two statuses.
.\" So far the Sun page
.\" Some additions - aeb
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR ecb_crypt (),
.BR cbc_crypt (),
.BR des_setparity ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
None.
.SH HISTORY
4.3BSD.
glibc 2.1.
Removed in glibc 2.28.
.P
Because they employ the DES block cipher,
which is no longer considered secure,
these functions were removed.
Applications should switch to a modern cryptography library, such as
.BR libgcrypt .
.SH SEE ALSO
.BR des (1),
.BR crypt (3),
.BR xcrypt (3)