157 lines
4.3 KiB
C
157 lines
4.3 KiB
C
/*
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* Copyright 2011-2016 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 <openssl/crypto.h>
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#include "modes_lcl.h"
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#include <string.h>
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int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx,
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const unsigned char iv[16],
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const unsigned char *inp, unsigned char *out,
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size_t len, int enc)
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{
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const union {
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long one;
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char little;
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} is_endian = {
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1
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};
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union {
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u64 u[2];
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u32 d[4];
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u8 c[16];
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} tweak, scratch;
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unsigned int i;
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if (len < 16)
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return -1;
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memcpy(tweak.c, iv, 16);
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(*ctx->block2) (tweak.c, tweak.c, ctx->key2);
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if (!enc && (len % 16))
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len -= 16;
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while (len >= 16) {
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#if defined(STRICT_ALIGNMENT)
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memcpy(scratch.c, inp, 16);
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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#else
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scratch.u[0] = ((u64 *)inp)[0] ^ tweak.u[0];
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scratch.u[1] = ((u64 *)inp)[1] ^ tweak.u[1];
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#endif
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(*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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#if defined(STRICT_ALIGNMENT)
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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memcpy(out, scratch.c, 16);
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#else
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((u64 *)out)[0] = scratch.u[0] ^= tweak.u[0];
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((u64 *)out)[1] = scratch.u[1] ^= tweak.u[1];
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#endif
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inp += 16;
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out += 16;
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len -= 16;
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if (len == 0)
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return 0;
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if (is_endian.little) {
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unsigned int carry, res;
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res = 0x87 & (((int)tweak.d[3]) >> 31);
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carry = (unsigned int)(tweak.u[0] >> 63);
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tweak.u[0] = (tweak.u[0] << 1) ^ res;
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tweak.u[1] = (tweak.u[1] << 1) | carry;
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} else {
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size_t c;
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for (c = 0, i = 0; i < 16; ++i) {
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/*
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* + substitutes for |, because c is 1 bit
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*/
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c += ((size_t)tweak.c[i]) << 1;
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tweak.c[i] = (u8)c;
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c = c >> 8;
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}
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tweak.c[0] ^= (u8)(0x87 & (0 - c));
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}
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}
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if (enc) {
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for (i = 0; i < len; ++i) {
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u8 c = inp[i];
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out[i] = scratch.c[i];
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scratch.c[i] = c;
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}
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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(*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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memcpy(out - 16, scratch.c, 16);
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} else {
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union {
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u64 u[2];
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u8 c[16];
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} tweak1;
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if (is_endian.little) {
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unsigned int carry, res;
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res = 0x87 & (((int)tweak.d[3]) >> 31);
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carry = (unsigned int)(tweak.u[0] >> 63);
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tweak1.u[0] = (tweak.u[0] << 1) ^ res;
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tweak1.u[1] = (tweak.u[1] << 1) | carry;
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} else {
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size_t c;
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for (c = 0, i = 0; i < 16; ++i) {
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/*
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* + substitutes for |, because c is 1 bit
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*/
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c += ((size_t)tweak.c[i]) << 1;
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tweak1.c[i] = (u8)c;
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c = c >> 8;
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}
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tweak1.c[0] ^= (u8)(0x87 & (0 - c));
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}
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#if defined(STRICT_ALIGNMENT)
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memcpy(scratch.c, inp, 16);
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scratch.u[0] ^= tweak1.u[0];
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scratch.u[1] ^= tweak1.u[1];
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#else
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scratch.u[0] = ((u64 *)inp)[0] ^ tweak1.u[0];
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scratch.u[1] = ((u64 *)inp)[1] ^ tweak1.u[1];
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#endif
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(*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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scratch.u[0] ^= tweak1.u[0];
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scratch.u[1] ^= tweak1.u[1];
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for (i = 0; i < len; ++i) {
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u8 c = inp[16 + i];
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out[16 + i] = scratch.c[i];
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scratch.c[i] = c;
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}
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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(*ctx->block1) (scratch.c, scratch.c, ctx->key1);
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#if defined(STRICT_ALIGNMENT)
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scratch.u[0] ^= tweak.u[0];
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scratch.u[1] ^= tweak.u[1];
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memcpy(out, scratch.c, 16);
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#else
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((u64 *)out)[0] = scratch.u[0] ^ tweak.u[0];
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((u64 *)out)[1] = scratch.u[1] ^ tweak.u[1];
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#endif
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}
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return 0;
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}
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