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openssl/crypto/modes/ocb128.c
Andy Polyakov 81f3d6323d modes/ocb128.c: split fixed block xors to aligned and misaligned. 
Main goal was to improve performance on RISC platforms, e.g. 10%
was measured on MIPS, POWER8...

Reviewed-by: Matt Caswell <matt@openssl.org>
2015-12-02 10:50:20 +01:00

585 lines
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/* ====================================================================
* Copyright (c) 2014 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*/
#include <string.h>
#include <openssl/crypto.h>
#include "modes_lcl.h"
#ifndef OPENSSL_NO_OCB
/*
* Calculate the number of binary trailing zero's in any given number
*/
static u32 ocb_ntz(u64 n)
{
u32 cnt = 0;
/*
* We do a right-to-left simple sequential search. This is surprisingly
* efficient as the distribution of trailing zeros is not uniform,
* e.g. the number of possible inputs with no trailing zeros is equal to
* the number with 1 or more; the number with exactly 1 is equal to the
* number with 2 or more, etc. Checking the last two bits covers 75% of
* all numbers. Checking the last three covers 87.5%
*/
while (!(n & 1)) {
n >>= 1;
cnt++;
}
return cnt;
}
/*
* Shift a block of 16 bytes left by shift bits
*/
static void ocb_block_lshift(OCB_BLOCK *in, size_t shift, OCB_BLOCK *out)
{
unsigned char shift_mask;
int i;
unsigned char mask[15];
shift_mask = 0xff;
shift_mask <<= (8 - shift);
for (i = 15; i >= 0; i--) {
if (i > 0) {
mask[i - 1] = in->c[i] & shift_mask;
mask[i - 1] >>= 8 - shift;
}
out->c[i] = in->c[i] << shift;
if (i != 15) {
out->c[i] ^= mask[i];
}
}
}
/*
* Perform a "double" operation as per OCB spec
*/
static void ocb_double(OCB_BLOCK *in, OCB_BLOCK *out)
{
unsigned char mask;
/*
* Calculate the mask based on the most significant bit. There are more
* efficient ways to do this - but this way is constant time
*/
mask = in->c[0] & 0x80;
mask >>= 7;
mask *= 135;
ocb_block_lshift(in, 1, out);
out->c[15] ^= mask;
}
/*
* Perform an xor on in1 and in2 - each of len bytes. Store result in out
*/
static void ocb_block_xor(const unsigned char *in1,
const unsigned char *in2, size_t len,
unsigned char *out)
{
size_t i;
for (i = 0; i < len; i++) {
out[i] = in1[i] ^ in2[i];
}
}
/*
* Lookup L_index in our lookup table. If we haven't already got it we need to
* calculate it
*/
static OCB_BLOCK *ocb_lookup_l(OCB128_CONTEXT *ctx, size_t idx)
{
size_t l_index = ctx->l_index;
if (idx <= l_index) {
return ctx->l + idx;
}
/* We don't have it - so calculate it */
if (idx >= ctx->max_l_index) {
/*
* Each additional entry allows to process almost double as
* much data, so that in linear world the table will need to
* be expanded with smaller and smaller increments. Originally
* it was doubling in size, which was a waste. Growing it
* linearly is not formally optimal, but is simpler to implement.
* We grow table by minimally required 4*n that would accommodate
* the index.
*/
ctx->max_l_index += (idx - ctx->max_l_index + 4) & ~3;
ctx->l =
OPENSSL_realloc(ctx->l, ctx->max_l_index * sizeof(OCB_BLOCK));
if (!ctx->l)
return NULL;
}
while (l_index <= idx) {
ocb_double(ctx->l + l_index, ctx->l + l_index + 1);
l_index++;
}
ctx->l_index = l_index;
return ctx->l + idx;
}
/*
* Encrypt a block from |in| and store the result in |out|
*/
static void ocb_encrypt(OCB128_CONTEXT *ctx, OCB_BLOCK *in, OCB_BLOCK *out,
void *keyenc)
{
ctx->encrypt(in->c, out->c, keyenc);
}
/*
* Decrypt a block from |in| and store the result in |out|
*/
static void ocb_decrypt(OCB128_CONTEXT *ctx, OCB_BLOCK *in, OCB_BLOCK *out,
void *keydec)
{
ctx->decrypt(in->c, out->c, keydec);
}
/*
* Create a new OCB128_CONTEXT
*/
OCB128_CONTEXT *CRYPTO_ocb128_new(void *keyenc, void *keydec,
block128_f encrypt, block128_f decrypt)
{
OCB128_CONTEXT *octx;
int ret;
if ((octx = OPENSSL_malloc(sizeof(*octx))) != NULL) {
ret = CRYPTO_ocb128_init(octx, keyenc, keydec, encrypt, decrypt);
if (ret)
return octx;
OPENSSL_free(octx);
}
return NULL;
}
/*
* Initialise an existing OCB128_CONTEXT
*/
int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
block128_f encrypt, block128_f decrypt)
{
memset(ctx, 0, sizeof(*ctx));
ctx->l_index = 0;
ctx->max_l_index = 5;
ctx->l = OPENSSL_malloc(ctx->max_l_index * 16);
if (ctx->l == NULL)
return 0;
/*
* We set both the encryption and decryption key schedules - decryption
* needs both. Don't really need decryption schedule if only doing
* encryption - but it simplifies things to take it anyway
*/
ctx->encrypt = encrypt;
ctx->decrypt = decrypt;
ctx->keyenc = keyenc;
ctx->keydec = keydec;
/* L_* = ENCIPHER(K, zeros(128)) */
ocb_encrypt(ctx, &ctx->l_star, &ctx->l_star, ctx->keyenc);
/* L_$ = double(L_*) */
ocb_double(&ctx->l_star, &ctx->l_dollar);
/* L_0 = double(L_$) */
ocb_double(&ctx->l_dollar, ctx->l);
/* L_{i} = double(L_{i-1}) */
ocb_double(ctx->l, ctx->l+1);
ocb_double(ctx->l+1, ctx->l+2);
ocb_double(ctx->l+2, ctx->l+3);
ocb_double(ctx->l+3, ctx->l+4);
ctx->l_index = 4; /* enough to process up to 496 bytes */
return 1;
}
/*
* Copy an OCB128_CONTEXT object
*/
int CRYPTO_ocb128_copy_ctx(OCB128_CONTEXT *dest, OCB128_CONTEXT *src,
void *keyenc, void *keydec)
{
memcpy(dest, src, sizeof(OCB128_CONTEXT));
if (keyenc)
dest->keyenc = keyenc;
if (keydec)
dest->keydec = keydec;
if (src->l) {
dest->l = OPENSSL_malloc(src->max_l_index * 16);
if (dest->l == NULL)
return 0;
memcpy(dest->l, src->l, (src->l_index + 1) * 16);
}
return 1;
}
/*
* Set the IV to be used for this operation. Must be 1 - 15 bytes.
*/
int CRYPTO_ocb128_setiv(OCB128_CONTEXT *ctx, const unsigned char *iv,
size_t len, size_t taglen)
{
unsigned char ktop[16], tmp[16], mask;
unsigned char stretch[24], nonce[16];
size_t bottom, shift;
/*
* Spec says IV is 120 bits or fewer - it allows non byte aligned lengths.
* We don't support this at this stage
*/
if ((len > 15) || (len < 1) || (taglen > 16) || (taglen < 1)) {
return -1;
}
/* Nonce = num2str(TAGLEN mod 128,7) || zeros(120-bitlen(N)) || 1 || N */
nonce[0] = ((taglen * 8) % 128) << 1;
memset(nonce + 1, 0, 15);
memcpy(nonce + 16 - len, iv, len);
nonce[15 - len] |= 1;
/* Ktop = ENCIPHER(K, Nonce[1..122] || zeros(6)) */
memcpy(tmp, nonce, 16);
tmp[15] &= 0xc0;
ctx->encrypt(tmp, ktop, ctx->keyenc);
/* Stretch = Ktop || (Ktop[1..64] xor Ktop[9..72]) */
memcpy(stretch, ktop, 16);
ocb_block_xor(ktop, ktop + 1, 8, stretch + 16);
/* bottom = str2num(Nonce[123..128]) */
bottom = nonce[15] & 0x3f;
/* Offset_0 = Stretch[1+bottom..128+bottom] */
shift = bottom % 8;
ocb_block_lshift((OCB_BLOCK *)(stretch + (bottom / 8)), shift,
&ctx->offset);
mask = 0xff;
mask <<= 8 - shift;
ctx->offset.c[15] |=
(*(stretch + (bottom / 8) + 16) & mask) >> (8 - shift);
return 1;
}
/*
* Provide any AAD. This can be called multiple times. Only the final time can
* have a partial block
*/
int CRYPTO_ocb128_aad(OCB128_CONTEXT *ctx, const unsigned char *aad,
size_t len)
{
u64 all_num_blocks, num_blocks;
u64 i;
OCB_BLOCK tmp1;
OCB_BLOCK tmp2;
int last_len;
/* Calculate the number of blocks of AAD provided now, and so far */
num_blocks = len / 16;
all_num_blocks = num_blocks + ctx->blocks_hashed;
/* Loop through all full blocks of AAD */
for (i = ctx->blocks_hashed + 1; i <= all_num_blocks; i++) {
OCB_BLOCK *lookup;
OCB_BLOCK *aad_block;
/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
lookup = ocb_lookup_l(ctx, ocb_ntz(i));
if (!lookup)
return 0;
ocb_block16_xor(&ctx->offset_aad, lookup, &ctx->offset_aad);
/* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
aad_block = (OCB_BLOCK *)(aad + ((i - ctx->blocks_hashed - 1) * 16));
ocb_block16_xor(&ctx->offset_aad, aad_block, &tmp1);
ocb_encrypt(ctx, &tmp1, &tmp2, ctx->keyenc);
ocb_block16_xor(&ctx->sum, &tmp2, &ctx->sum);
}
/*
* Check if we have any partial blocks left over. This is only valid in the
* last call to this function
*/
last_len = len % 16;
if (last_len > 0) {
/* Offset_* = Offset_m xor L_* */
ocb_block16_xor(&ctx->offset_aad, &ctx->l_star, &ctx->offset_aad);
/* CipherInput = (A_* || 1 || zeros(127-bitlen(A_*))) xor Offset_* */
memset(&tmp1, 0, 16);
memcpy(&tmp1, aad + (num_blocks * 16), last_len);
((unsigned char *)&tmp1)[last_len] = 0x80;
ocb_block16_xor(&ctx->offset_aad, &tmp1, &tmp2);
/* Sum = Sum_m xor ENCIPHER(K, CipherInput) */
ocb_encrypt(ctx, &tmp2, &tmp1, ctx->keyenc);
ocb_block16_xor(&ctx->sum, &tmp1, &ctx->sum);
}
ctx->blocks_hashed = all_num_blocks;
return 1;
}
/*
* Provide any data to be encrypted. This can be called multiple times. Only
* the final time can have a partial block
*/
int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
const unsigned char *in, unsigned char *out,
size_t len)
{
u64 i;
u64 all_num_blocks, num_blocks;
OCB_BLOCK tmp1;
OCB_BLOCK tmp2;
OCB_BLOCK pad;
int last_len;
/*
* Calculate the number of blocks of data to be encrypted provided now, and
* so far
*/
num_blocks = len / 16;
all_num_blocks = num_blocks + ctx->blocks_processed;
/* Loop through all full blocks to be encrypted */
for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
OCB_BLOCK *lookup;
OCB_BLOCK *inblock;
OCB_BLOCK *outblock;
/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
lookup = ocb_lookup_l(ctx, ocb_ntz(i));
if (!lookup)
return 0;
ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
/* C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i) */
inblock = (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
/* Checksum_i = Checksum_{i-1} xor P_i */
ocb_block16_xor_misaligned(&ctx->checksum, inblock, &ctx->checksum);
ocb_encrypt(ctx, &tmp1, &tmp2, ctx->keyenc);
outblock =
(OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
}
/*
* Check if we have any partial blocks left over. This is only valid in the
* last call to this function
*/
last_len = len % 16;
if (last_len > 0) {
/* Offset_* = Offset_m xor L_* */
ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
/* Pad = ENCIPHER(K, Offset_*) */
ocb_encrypt(ctx, &ctx->offset, &pad, ctx->keyenc);
/* C_* = P_* xor Pad[1..bitlen(P_*)] */
ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
out + (num_blocks * 16));
/* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
memset(&tmp1, 0, 16);
memcpy(&tmp1, in + (len / 16) * 16, last_len);
((unsigned char *)(&tmp1))[last_len] = 0x80;
ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
}
ctx->blocks_processed = all_num_blocks;
return 1;
}
/*
* Provide any data to be decrypted. This can be called multiple times. Only
* the final time can have a partial block
*/
int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
const unsigned char *in, unsigned char *out,
size_t len)
{
u64 i;
u64 all_num_blocks, num_blocks;
OCB_BLOCK tmp1;
OCB_BLOCK tmp2;
OCB_BLOCK pad;
int last_len;
/*
* Calculate the number of blocks of data to be decrypted provided now, and
* so far
*/
num_blocks = len / 16;
all_num_blocks = num_blocks + ctx->blocks_processed;
/* Loop through all full blocks to be decrypted */
for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
OCB_BLOCK *inblock;
OCB_BLOCK *outblock;
/* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
OCB_BLOCK *lookup = ocb_lookup_l(ctx, ocb_ntz(i));
if (!lookup)
return 0;
ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
/* P_i = Offset_i xor DECIPHER(K, C_i xor Offset_i) */
inblock = (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
ocb_decrypt(ctx, &tmp1, &tmp2, ctx->keydec);
outblock =
(OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
/* Checksum_i = Checksum_{i-1} xor P_i */
ocb_block16_xor_misaligned(&ctx->checksum, outblock, &ctx->checksum);
}
/*
* Check if we have any partial blocks left over. This is only valid in the
* last call to this function
*/
last_len = len % 16;
if (last_len > 0) {
/* Offset_* = Offset_m xor L_* */
ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
/* Pad = ENCIPHER(K, Offset_*) */
ocb_encrypt(ctx, &ctx->offset, &pad, ctx->keyenc);
/* P_* = C_* xor Pad[1..bitlen(C_*)] */
ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
out + (num_blocks * 16));
/* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
memset(&tmp1, 0, 16);
memcpy(&tmp1, out + (len / 16) * 16, last_len);
((unsigned char *)(&tmp1))[last_len] = 0x80;
ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
}
ctx->blocks_processed = all_num_blocks;
return 1;
}
/*
* Calculate the tag and verify it against the supplied tag
*/
int CRYPTO_ocb128_finish(OCB128_CONTEXT *ctx, const unsigned char *tag,
size_t len)
{
OCB_BLOCK tmp1, tmp2;
/*
* Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A)
*/
ocb_block16_xor(&ctx->checksum, &ctx->offset, &tmp1);
ocb_block16_xor(&tmp1, &ctx->l_dollar, &tmp2);
ocb_encrypt(ctx, &tmp2, &tmp1, ctx->keyenc);
ocb_block16_xor(&tmp1, &ctx->sum, &ctx->tag);
if (len > 16 || len < 1) {
return -1;
}
/* Compare the tag if we've been given one */
if (tag)
return CRYPTO_memcmp(&ctx->tag, tag, len);
else
return -1;
}
/*
* Retrieve the calculated tag
*/
int CRYPTO_ocb128_tag(OCB128_CONTEXT *ctx, unsigned char *tag, size_t len)
{
if (len > 16 || len < 1) {
return -1;
}
/* Calculate the tag */
CRYPTO_ocb128_finish(ctx, NULL, 0);
/* Copy the tag into the supplied buffer */
memcpy(tag, &ctx->tag, len);
return 1;
}
/*
* Release all resources
*/
void CRYPTO_ocb128_cleanup(OCB128_CONTEXT *ctx)
{
if (ctx) {
OPENSSL_clear_free(ctx->l, ctx->max_l_index * 16);
OPENSSL_cleanse(ctx, sizeof(*ctx));
}
}
#endif /* OPENSSL_NO_OCB */
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