[331] | 1 | /*
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| 2 | * Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the OpenSSL license (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | #include <openssl/crypto.h>
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| 11 | #include "modes_lcl.h"
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| 12 | #include <string.h>
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| 13 |
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| 14 | /*
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| 15 | * The input and output encrypted as though 128bit cfb mode is being used.
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| 16 | * The extra state information to record how much of the 128bit block we have
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| 17 | * used is contained in *num;
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| 18 | */
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| 19 | void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
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| 20 | size_t len, const void *key,
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| 21 | unsigned char ivec[16], int *num,
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| 22 | int enc, block128_f block)
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| 23 | {
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| 24 | unsigned int n;
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| 25 | size_t l = 0;
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| 26 |
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| 27 | n = *num;
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| 28 |
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| 29 | if (enc) {
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| 30 | #if !defined(OPENSSL_SMALL_FOOTPRINT)
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| 31 | if (16 % sizeof(size_t) == 0) { /* always true actually */
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| 32 | do {
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| 33 | while (n && len) {
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| 34 | *(out++) = ivec[n] ^= *(in++);
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| 35 | --len;
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| 36 | n = (n + 1) % 16;
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| 37 | }
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| 38 | # if defined(STRICT_ALIGNMENT)
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| 39 | if (((size_t)in | (size_t)out | (size_t)ivec) %
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| 40 | sizeof(size_t) != 0)
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| 41 | break;
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| 42 | # endif
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| 43 | while (len >= 16) {
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| 44 | (*block) (ivec, ivec, key);
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| 45 | for (; n < 16; n += sizeof(size_t)) {
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| 46 | *(size_t *)(out + n) =
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| 47 | *(size_t *)(ivec + n) ^= *(size_t *)(in + n);
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| 48 | }
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| 49 | len -= 16;
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| 50 | out += 16;
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| 51 | in += 16;
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| 52 | n = 0;
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| 53 | }
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| 54 | if (len) {
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| 55 | (*block) (ivec, ivec, key);
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| 56 | while (len--) {
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| 57 | out[n] = ivec[n] ^= in[n];
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| 58 | ++n;
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| 59 | }
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| 60 | }
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| 61 | *num = n;
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| 62 | return;
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| 63 | } while (0);
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| 64 | }
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| 65 | /* the rest would be commonly eliminated by x86* compiler */
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| 66 | #endif
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| 67 | while (l < len) {
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| 68 | if (n == 0) {
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| 69 | (*block) (ivec, ivec, key);
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| 70 | }
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| 71 | out[l] = ivec[n] ^= in[l];
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| 72 | ++l;
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| 73 | n = (n + 1) % 16;
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| 74 | }
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| 75 | *num = n;
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| 76 | } else {
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| 77 | #if !defined(OPENSSL_SMALL_FOOTPRINT)
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| 78 | if (16 % sizeof(size_t) == 0) { /* always true actually */
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| 79 | do {
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| 80 | while (n && len) {
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| 81 | unsigned char c;
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| 82 | *(out++) = ivec[n] ^ (c = *(in++));
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| 83 | ivec[n] = c;
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| 84 | --len;
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| 85 | n = (n + 1) % 16;
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| 86 | }
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| 87 | # if defined(STRICT_ALIGNMENT)
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| 88 | if (((size_t)in | (size_t)out | (size_t)ivec) %
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| 89 | sizeof(size_t) != 0)
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| 90 | break;
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| 91 | # endif
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| 92 | while (len >= 16) {
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| 93 | (*block) (ivec, ivec, key);
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| 94 | for (; n < 16; n += sizeof(size_t)) {
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| 95 | size_t t = *(size_t *)(in + n);
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| 96 | *(size_t *)(out + n) = *(size_t *)(ivec + n) ^ t;
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| 97 | *(size_t *)(ivec + n) = t;
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| 98 | }
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| 99 | len -= 16;
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| 100 | out += 16;
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| 101 | in += 16;
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| 102 | n = 0;
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| 103 | }
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| 104 | if (len) {
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| 105 | (*block) (ivec, ivec, key);
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| 106 | while (len--) {
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| 107 | unsigned char c;
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| 108 | out[n] = ivec[n] ^ (c = in[n]);
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| 109 | ivec[n] = c;
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| 110 | ++n;
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| 111 | }
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| 112 | }
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| 113 | *num = n;
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| 114 | return;
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| 115 | } while (0);
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| 116 | }
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| 117 | /* the rest would be commonly eliminated by x86* compiler */
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| 118 | #endif
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| 119 | while (l < len) {
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| 120 | unsigned char c;
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| 121 | if (n == 0) {
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| 122 | (*block) (ivec, ivec, key);
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| 123 | }
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| 124 | out[l] = ivec[n] ^ (c = in[l]);
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| 125 | ivec[n] = c;
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| 126 | ++l;
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| 127 | n = (n + 1) % 16;
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| 128 | }
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| 129 | *num = n;
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| 130 | }
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| 131 | }
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| 132 |
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| 133 | /*
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| 134 | * This expects a single block of size nbits for both in and out. Note that
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| 135 | * it corrupts any extra bits in the last byte of out
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| 136 | */
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| 137 | static void cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
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| 138 | int nbits, const void *key,
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| 139 | unsigned char ivec[16], int enc,
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| 140 | block128_f block)
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| 141 | {
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| 142 | int n, rem, num;
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| 143 | unsigned char ovec[16 * 2 + 1]; /* +1 because we dereference (but don't
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| 144 | * use) one byte off the end */
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| 145 |
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| 146 | if (nbits <= 0 || nbits > 128)
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| 147 | return;
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| 148 |
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| 149 | /* fill in the first half of the new IV with the current IV */
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| 150 | memcpy(ovec, ivec, 16);
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| 151 | /* construct the new IV */
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| 152 | (*block) (ivec, ivec, key);
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| 153 | num = (nbits + 7) / 8;
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| 154 | if (enc) /* encrypt the input */
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| 155 | for (n = 0; n < num; ++n)
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| 156 | out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
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| 157 | else /* decrypt the input */
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| 158 | for (n = 0; n < num; ++n)
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| 159 | out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
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| 160 | /* shift ovec left... */
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| 161 | rem = nbits % 8;
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| 162 | num = nbits / 8;
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| 163 | if (rem == 0)
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| 164 | memcpy(ivec, ovec + num, 16);
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| 165 | else
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| 166 | for (n = 0; n < 16; ++n)
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| 167 | ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);
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| 168 |
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| 169 | /* it is not necessary to cleanse ovec, since the IV is not secret */
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| 170 | }
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| 171 |
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| 172 | /* N.B. This expects the input to be packed, MS bit first */
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| 173 | void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
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| 174 | size_t bits, const void *key,
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| 175 | unsigned char ivec[16], int *num,
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| 176 | int enc, block128_f block)
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| 177 | {
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| 178 | size_t n;
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| 179 | unsigned char c[1], d[1];
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| 180 |
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| 181 | for (n = 0; n < bits; ++n) {
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| 182 | c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
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| 183 | cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
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| 184 | out[n / 8] = (out[n / 8] & ~(1 << (unsigned int)(7 - n % 8))) |
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| 185 | ((d[0] & 0x80) >> (unsigned int)(n % 8));
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| 186 | }
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| 187 | }
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| 188 |
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| 189 | void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
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| 190 | size_t length, const void *key,
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| 191 | unsigned char ivec[16], int *num,
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| 192 | int enc, block128_f block)
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| 193 | {
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| 194 | size_t n;
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| 195 |
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| 196 | for (n = 0; n < length; ++n)
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| 197 | cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
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| 198 | }
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