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