/* $OpenBSD: ofb_enc.c,v 1.8 2023/07/08 07:11:07 beck Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#include "des_local.h"
/* The input and output are loaded in multiples of 8 bits.
* What this means is that if you hame numbits=12 and length=2
* the first 12 bits will be retrieved from the first byte and half
* the second. The second 12 bits will come from the 3rd and half the 4th
* byte.
*/
void
DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
long length, DES_key_schedule *schedule,
DES_cblock *ivec)
{
DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7)/8;
DES_LONG mask0, mask1;
long l = length;
int num = numbits;
DES_LONG ti[2];
unsigned char *iv;
if (num > 64)
return;
if (num > 32) {
mask0 = 0xffffffffL;
if (num >= 64)
mask1 = mask0;
else
mask1 = (1L << (num - 32)) - 1;
} else {
if (num == 32)
mask0 = 0xffffffffL;
else
mask0 = (1L << num) - 1;
mask1 = 0x00000000L;
}
iv = &(*ivec)[0];
c2l(iv, v0);
c2l(iv, v1);
ti[0] = v0;
ti[1] = v1;
while (l-- > 0) {
ti[0] = v0;
ti[1] = v1;
DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
vv0 = ti[0];
vv1 = ti[1];
c2ln(in, d0, d1, n);
in += n;
d0 = (d0 ^ vv0) & mask0;
d1 = (d1 ^ vv1) & mask1;
l2cn(d0, d1, out, n);
out += n;
if (num == 32) {
v0 = v1;
v1 = vv0;
} else if (num == 64) {
v0 = vv0;
v1 = vv1;
} else if (num > 32) { /* && num != 64 */
v0 = ((v1 >> (num - 32))|(vv0 << (64 - num))) &
0xffffffffL;
v1 = ((vv0 >> (num - 32))|(vv1 << (64 - num))) &
0xffffffffL;
} else /* num < 32 */ {
v0 = ((v0 >> num)|(v1 << (32 - num))) & 0xffffffffL;
v1 = ((v1 >> num)|(vv0 << (32 - num))) & 0xffffffffL;
}
}
iv = &(*ivec)[0];
l2c(v0, iv);
l2c(v1, iv);
v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0;
}