| 1 | /*
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| 2 | * Copyright 2011-2016 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_local.h"
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| 12 | #include <string.h>
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| 13 |
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| 14 | int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx,
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| 15 | const unsigned char iv[16],
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| 16 | const unsigned char *inp, unsigned char *out,
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| 17 | size_t len, int enc)
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| 18 | {
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| 19 | const union {
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| 20 | long one;
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| 21 | char little;
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| 22 | } is_endian = {
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| 23 | 1
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| 24 | };
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| 25 | union {
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| 26 | u64 u[2];
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| 27 | u32 d[4];
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| 28 | u8 c[16];
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| 29 | } tweak, scratch;
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| 30 | unsigned int i;
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| 31 |
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| 32 | if (len < 16)
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| 33 | return -1;
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| 34 |
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| 35 | memcpy(tweak.c, iv, 16);
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| 36 |
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| 37 | (*ctx->block2) (tweak.c, tweak.c, ctx->key2);
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| 38 |
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| 39 | if (!enc && (len % 16))
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| 40 | len -= 16;
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| 41 |
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| 42 | while (len >= 16) {
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| 43 | #if defined(STRICT_ALIGNMENT)
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| 44 | memcpy(scratch.c, inp, 16);
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| 45 | scratch.u[0] ^= tweak.u[0];
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| 46 | scratch.u[1] ^= tweak.u[1];
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| 47 | #else
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| 48 | scratch.u[0] = ((u64 *)inp)[0] ^ tweak.u[0];
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| 49 | scratch.u[1] = ((u64 *)inp)[1] ^ tweak.u[1];
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| 50 | #endif
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| 51 | (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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| 52 | #if defined(STRICT_ALIGNMENT)
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| 53 | scratch.u[0] ^= tweak.u[0];
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| 54 | scratch.u[1] ^= tweak.u[1];
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| 55 | memcpy(out, scratch.c, 16);
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| 56 | #else
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| 57 | ((u64 *)out)[0] = scratch.u[0] ^= tweak.u[0];
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| 58 | ((u64 *)out)[1] = scratch.u[1] ^= tweak.u[1];
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| 59 | #endif
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| 60 | inp += 16;
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| 61 | out += 16;
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| 62 | len -= 16;
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| 63 |
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| 64 | if (len == 0)
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| 65 | return 0;
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| 66 |
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| 67 | if (is_endian.little) {
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| 68 | unsigned int carry, res;
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| 69 |
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| 70 | res = 0x87 & (((int)tweak.d[3]) >> 31);
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| 71 | carry = (unsigned int)(tweak.u[0] >> 63);
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| 72 | tweak.u[0] = (tweak.u[0] << 1) ^ res;
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| 73 | tweak.u[1] = (tweak.u[1] << 1) | carry;
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| 74 | } else {
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| 75 | size_t c;
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| 76 |
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| 77 | for (c = 0, i = 0; i < 16; ++i) {
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| 78 | /*
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| 79 | * + substitutes for |, because c is 1 bit
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| 80 | */
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| 81 | c += ((size_t)tweak.c[i]) << 1;
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| 82 | tweak.c[i] = (u8)c;
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| 83 | c = c >> 8;
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| 84 | }
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| 85 | tweak.c[0] ^= (u8)(0x87 & (0 - c));
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| 86 | }
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| 87 | }
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| 88 | if (enc) {
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| 89 | for (i = 0; i < len; ++i) {
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| 90 | u8 c = inp[i];
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| 91 | out[i] = scratch.c[i];
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| 92 | scratch.c[i] = c;
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| 93 | }
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| 94 | scratch.u[0] ^= tweak.u[0];
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| 95 | scratch.u[1] ^= tweak.u[1];
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| 96 | (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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| 97 | scratch.u[0] ^= tweak.u[0];
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| 98 | scratch.u[1] ^= tweak.u[1];
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| 99 | memcpy(out - 16, scratch.c, 16);
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| 100 | } else {
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| 101 | union {
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| 102 | u64 u[2];
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| 103 | u8 c[16];
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| 104 | } tweak1;
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| 105 |
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| 106 | if (is_endian.little) {
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| 107 | unsigned int carry, res;
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| 108 |
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| 109 | res = 0x87 & (((int)tweak.d[3]) >> 31);
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| 110 | carry = (unsigned int)(tweak.u[0] >> 63);
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| 111 | tweak1.u[0] = (tweak.u[0] << 1) ^ res;
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| 112 | tweak1.u[1] = (tweak.u[1] << 1) | carry;
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| 113 | } else {
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| 114 | size_t c;
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| 115 |
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| 116 | for (c = 0, i = 0; i < 16; ++i) {
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| 117 | /*
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| 118 | * + substitutes for |, because c is 1 bit
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| 119 | */
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| 120 | c += ((size_t)tweak.c[i]) << 1;
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| 121 | tweak1.c[i] = (u8)c;
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| 122 | c = c >> 8;
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| 123 | }
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| 124 | tweak1.c[0] ^= (u8)(0x87 & (0 - c));
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| 125 | }
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| 126 | #if defined(STRICT_ALIGNMENT)
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| 127 | memcpy(scratch.c, inp, 16);
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| 128 | scratch.u[0] ^= tweak1.u[0];
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| 129 | scratch.u[1] ^= tweak1.u[1];
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| 130 | #else
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| 131 | scratch.u[0] = ((u64 *)inp)[0] ^ tweak1.u[0];
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| 132 | scratch.u[1] = ((u64 *)inp)[1] ^ tweak1.u[1];
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| 133 | #endif
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| 134 | (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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| 135 | scratch.u[0] ^= tweak1.u[0];
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| 136 | scratch.u[1] ^= tweak1.u[1];
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| 137 |
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| 138 | for (i = 0; i < len; ++i) {
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| 139 | u8 c = inp[16 + i];
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| 140 | out[16 + i] = scratch.c[i];
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| 141 | scratch.c[i] = c;
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| 142 | }
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| 143 | scratch.u[0] ^= tweak.u[0];
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| 144 | scratch.u[1] ^= tweak.u[1];
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| 145 | (*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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| 146 | #if defined(STRICT_ALIGNMENT)
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| 147 | scratch.u[0] ^= tweak.u[0];
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| 148 | scratch.u[1] ^= tweak.u[1];
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| 149 | memcpy(out, scratch.c, 16);
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| 150 | #else
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| 151 | ((u64 *)out)[0] = scratch.u[0] ^ tweak.u[0];
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| 152 | ((u64 *)out)[1] = scratch.u[1] ^ tweak.u[1];
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| 153 | #endif
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| 154 | }
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| 155 |
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| 156 | return 0;
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| 157 | }
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