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.\" @(#)des_crypt.3     2.1 88/08/11 4.0 RPCSRC; from 1.16 88/03/02 SMI;
.\" $FreeBSD: src/lib/libc/rpc/des_crypt.3,v 1.4 2000/03/02 09:13:45 sheldonh Exp $
.\"
.TH DES_CRYPT 3  "6 October 1987"
.SH NAME
des_crypt, ecb_crypt, cbc_crypt, des_setparity \- fast DES encryption
.SH SYNOPSIS
.nf
.B #include <des_crypt.h>
.LP
.B int ecb_crypt(key, data, datalen, mode)
.B char *key;
.B char *data;
.B unsigned datalen;
.B unsigned mode;
.LP
.B int cbc_crypt(key, data, datalen, mode, ivec)
.B char *key;
.B char *data;
.B unsigned datalen;
.B unsigned mode;
.B char *ivec;
.LP
.B void des_setparity(key)
.B char *key;
.fi
.SH DESCRIPTION
.IX encryption cbc_crypt "" \fLcbc_crypt\fP
.IX "des encryption" cbc_crypt "DES encryption" \fLcbc_crypt\fP
.IX encryption des_setparity "" \fLdes_setparity\fP
.IX "des encryption" des_setparity "DES encryption" \fLdes_setparity\fP
.B ecb_crypt(\|)
and
.B cbc_crypt(\|)
implement the
.SM NBS
.SM DES
(Data Encryption Standard).
These routines are faster and more general purpose than
.BR crypt (3).
They also are able to utilize
.SM DES
hardware if it is available.
.B ecb_crypt(\|)
encrypts in
.SM ECB
(Electronic Code Book)
mode, which encrypts blocks of data independently.
.B cbc_crypt(\|)
encrypts in
.SM CBC
(Cipher Block Chaining)
mode, which chains together
successive blocks.
.SM CBC
mode protects against insertions, deletions and
substitutions of blocks.
Also, regularities in the clear text will
not appear in the cipher text.
.LP
Here is how to use these routines.  The first parameter,
.IR key ,
is the 8-byte encryption key with parity.
To set the key's parity, which for
.SM DES
is in the low bit of each byte, use
.IR des_setparity .
The second parameter,
.IR data ,
contains the data to be encrypted or decrypted.
The
third parameter,
.IR datalen ,
is the length in bytes of
.IR data ,
which must be a multiple of 8. The fourth parameter,
.IR mode ,
is formed by
.SM OR\s0'ing
together some things.  For the encryption direction 'or' in either
.SM DES_ENCRYPT
or
.SM DES_DECRYPT\s0.
For software versus hardware
encryption, 'or' in either
.SM DES_HW
or
.SM DES_SW\s0.
If
.SM DES_HW
is specified, and there is no hardware, then the encryption is performed
in software and the routine returns
.SM DESERR_NOHWDEVICE\s0.
For
.IR cbc_crypt ,
the parameter
.I ivec
is the the 8-byte initialization
vector for the chaining.  It is updated to the next initialization
vector upon return.
.LP
.SH "SEE ALSO"
.BR des (1),
.BR crypt (3)
.SH DIAGNOSTICS
.PD 0
.TP 20
.SM DESERR_NONE
No error.
.TP
.SM DESERR_NOHWDEVICE
Encryption succeeded, but done in software instead of the requested hardware.
.TP
.SM DESERR_HWERR
An error occurred in the hardware or driver.
.TP
.SM DESERR_BADPARAM
Bad parameter to routine.
.PD
.LP
Given a result status
.IR stat ,
the macro
.SM DES_FAILED\c
.BR ( stat )
is false only for the first two statuses.
.SH RESTRICTIONS
These routines are not available in RPCSRC 4.0.
This information is provided to describe the DES interface expected by
Secure RPC.