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82 lines
2.4 KiB
C
82 lines
2.4 KiB
C
/*
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* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "des_local.h"
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/*
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* The input and output are loaded in multiples of 8 bits. What this means is
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* that if you have numbits=12 and length=2 the first 12 bits will be
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* retrieved from the first byte and half the second. The second 12 bits
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* will come from the 3rd and half the 4th byte.
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*/
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void 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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register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8;
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register DES_LONG mask0, mask1;
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register long l = length;
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register 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))) & 0xffffffffL;
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v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 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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