ref: e86bd6a50933e99899d63de755d81b9805827a15
dir: /third_party/boringssl/src/crypto/fipsmodule/modes/ctr.c/
/* ====================================================================
* Copyright (c) 2008 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 <openssl/type_check.h>
#include <assert.h>
#include <string.h>
#include "internal.h"
#include "../../internal.h"
// NOTE: the IV/counter CTR mode is big-endian. The code itself
// is endian-neutral.
// increment counter (128-bit int) by 1
static void ctr128_inc(uint8_t *counter) {
uint32_t n = 16, c = 1;
do {
--n;
c += counter[n];
counter[n] = (uint8_t) c;
c >>= 8;
} while (n);
}
OPENSSL_STATIC_ASSERT(16 % sizeof(crypto_word_t) == 0,
"block cannot be divided into crypto_word_t");
// The input encrypted as though 128bit counter mode is being used. The extra
// state information to record how much of the 128bit block we have used is
// contained in *num, and the encrypted counter is kept in ecount_buf. Both
// *num and ecount_buf must be initialised with zeros before the first call to
// CRYPTO_ctr128_encrypt().
//
// This algorithm assumes that the counter is in the x lower bits of the IV
// (ivec), and that the application has full control over overflow and the rest
// of the IV. This implementation takes NO responsibility for checking that
// the counter doesn't overflow into the rest of the IV when incremented.
void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
const AES_KEY *key, uint8_t ivec[16],
uint8_t ecount_buf[16], unsigned int *num,
block128_f block) {
unsigned int n;
assert(key && ecount_buf && num);
assert(len == 0 || (in && out));
assert(*num < 16);
n = *num;
while (n && len) {
*(out++) = *(in++) ^ ecount_buf[n];
--len;
n = (n + 1) % 16;
}
while (len >= 16) {
(*block)(ivec, ecount_buf, key);
ctr128_inc(ivec);
for (n = 0; n < 16; n += sizeof(crypto_word_t)) {
CRYPTO_store_word_le(out + n, CRYPTO_load_word_le(in + n) ^
CRYPTO_load_word_le(ecount_buf + n));
}
len -= 16;
out += 16;
in += 16;
n = 0;
}
if (len) {
(*block)(ivec, ecount_buf, key);
ctr128_inc(ivec);
while (len--) {
out[n] = in[n] ^ ecount_buf[n];
++n;
}
}
*num = n;
}
// increment upper 96 bits of 128-bit counter by 1
static void ctr96_inc(uint8_t *counter) {
uint32_t n = 12, c = 1;
do {
--n;
c += counter[n];
counter[n] = (uint8_t) c;
c >>= 8;
} while (n);
}
void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, size_t len,
const AES_KEY *key, uint8_t ivec[16],
uint8_t ecount_buf[16], unsigned int *num,
ctr128_f func) {
unsigned int n, ctr32;
assert(key && ecount_buf && num);
assert(len == 0 || (in && out));
assert(*num < 16);
n = *num;
while (n && len) {
*(out++) = *(in++) ^ ecount_buf[n];
--len;
n = (n + 1) % 16;
}
ctr32 = CRYPTO_load_u32_be(ivec + 12);
while (len >= 16) {
size_t blocks = len / 16;
// 1<<28 is just a not-so-small yet not-so-large number...
// Below condition is practically never met, but it has to
// be checked for code correctness.
if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) {
blocks = (1U << 28);
}
// As (*func) operates on 32-bit counter, caller
// has to handle overflow. 'if' below detects the
// overflow, which is then handled by limiting the
// amount of blocks to the exact overflow point...
ctr32 += (uint32_t)blocks;
if (ctr32 < blocks) {
blocks -= ctr32;
ctr32 = 0;
}
(*func)(in, out, blocks, key, ivec);
// (*func) does not update ivec, caller does:
CRYPTO_store_u32_be(ivec + 12, ctr32);
// ... overflow was detected, propogate carry.
if (ctr32 == 0) {
ctr96_inc(ivec);
}
blocks *= 16;
len -= blocks;
out += blocks;
in += blocks;
}
if (len) {
OPENSSL_memset(ecount_buf, 0, 16);
(*func)(ecount_buf, ecount_buf, 1, key, ivec);
++ctr32;
CRYPTO_store_u32_be(ivec + 12, ctr32);
if (ctr32 == 0) {
ctr96_inc(ivec);
}
while (len--) {
out[n] = in[n] ^ ecount_buf[n];
++n;
}
}
*num = n;
}