.\" @(#)des_crypt.3	2.1 88/08/11 4.0 RPCSRC; from 1.16 88/03/02 SMI;

.\"

.Dd October 6, 1987

.Dt DES_CRYPT 3

.Os

.Sh NAME

.Nm des_crypt , ecb_crypt , cbc_crypt , des_setparity

.Nd "fast DES encryption"

.Sh SYNOPSIS

.In rpc/des_crypt.h

.Ft int

.Fn ecb_crypt "char *key" "char *data" "unsigned datalen" "unsigned mode"

.Ft int

.Fn cbc_crypt "char *key" "char *data" "unsigned datalen" "unsigned mode" "char *ivec"

.Ft void

.Fn des_setparity "char *key"

.Sh DESCRIPTION

The

.Fn ecb_crypt

and

.Fn cbc_crypt

functions

implement the

.Tn NBS

.Tn DES

(Data Encryption Standard).

These routines are faster and more general purpose than

.Xr crypt 3 .

They also are able to utilize

.Tn DES

hardware if it is available.

The

.Fn ecb_crypt

function

encrypts in

.Tn ECB

(Electronic Code Book)

mode, which encrypts blocks of data independently.

The

.Fn cbc_crypt

function

encrypts in

.Tn CBC

(Cipher Block Chaining)

mode, which chains together

successive blocks.

.Tn CBC

mode protects against insertions, deletions and

substitutions of blocks.

Also, regularities in the clear text will

not appear in the cipher text.

.Pp

Here is how to use these routines.

The first argument,

.Fa key ,

is the 8-byte encryption key with parity.

To set the key's parity, which for

.Tn DES

is in the low bit of each byte, use

.Fn des_setparity .

The second argument,

.Fa data ,

contains the data to be encrypted or decrypted.

The

third argument,

.Fa datalen ,

is the length in bytes of

.Fa data ,

which must be a multiple of 8.

The fourth argument,

.Fa mode ,

is formed by

.Em OR Ns 'ing

together some things.

For the encryption direction

.Em OR

in either

.Dv DES_ENCRYPT

or

.Dv DES_DECRYPT .

For software versus hardware

encryption,

.Em OR

in either

.Dv DES_HW

or

.Dv DES_SW .

If

.Dv DES_HW

is specified, and there is no hardware, then the encryption is performed

in software and the routine returns

.Er DESERR_NOHWDEVICE .

For

.Fn cbc_crypt ,

the

.Fa ivec

argument

is the 8-byte initialization

vector for the chaining.

It is updated to the next initialization

vector upon return.

.Sh ERRORS

.Bl -tag -width [DESERR_NOHWDEVICE] -compact

.It Bq Er DESERR_NONE

No error.

.It Bq Er DESERR_NOHWDEVICE

Encryption succeeded, but done in software instead of the requested hardware.

.It Bq Er DESERR_HWERR

An error occurred in the hardware or driver.

.It Bq Er DESERR_BADPARAM

Bad argument to routine.

.El

.Pp

Given a result status

.Va stat ,

the macro

.Fn DES_FAILED stat

is false only for the first two statuses.

.Sh AVAILABILITY

The

.Fn ecb_crypt ,

.Fn cbc_crypt ,

and

.Fn des_setparity

functions are part of libtirpc.

.Sh SEE ALSO

.\" .Xr des 1 ,

.Xr crypt 3

.Sh RESTRICTIONS

These routines are not available in RPCSRC 4.0.

This information is provided to describe the

.Tn DES

interface expected by

Secure RPC.