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- /* ====================================================================
- * 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/modes.h>
-
- #include <assert.h>
- #include <string.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;
- uint8_t c;
-
- do {
- --n;
- c = counter[n];
- ++c;
- counter[n] = c;
- if (c) {
- return;
- }
- } while (n);
- }
-
- /* 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 void *key, uint8_t ivec[16],
- uint8_t ecount_buf[16], unsigned int *num,
- block128_f block) {
- unsigned int n;
-
- assert(in && out && key && ecount_buf && num);
- assert(*num < 16);
- assert((16 % sizeof(size_t)) == 0);
-
- n = *num;
-
- while (n && len) {
- *(out++) = *(in++) ^ ecount_buf[n];
- --len;
- n = (n + 1) % 16;
- }
-
- #if STRICT_ALIGNMENT
- if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
- size_t l = 0;
- while (l < len) {
- if (n == 0) {
- (*block)(ivec, ecount_buf, key);
- ctr128_inc(ivec);
- }
- out[l] = in[l] ^ ecount_buf[n];
- ++l;
- n = (n + 1) % 16;
- }
-
- *num = n;
- return;
- }
- #endif
-
- while (len >= 16) {
- (*block)(ivec, ecount_buf, key);
- ctr128_inc(ivec);
- for (; n < 16; n += sizeof(size_t)) {
- *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(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;
- uint8_t c;
-
- do {
- --n;
- c = counter[n];
- ++c;
- counter[n] = c;
- if (c) {
- return;
- }
- } while (n);
- }
-
- void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out,
- size_t len, const void *key,
- uint8_t ivec[16],
- uint8_t ecount_buf[16],
- unsigned int *num, ctr128_f func) {
- unsigned int n, ctr32;
-
- assert(in && out && key && ecount_buf && num);
- assert(*num < 16);
-
- n = *num;
-
- while (n && len) {
- *(out++) = *(in++) ^ ecount_buf[n];
- --len;
- n = (n + 1) % 16;
- }
-
- ctr32 = GETU32(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: */
- PUTU32(ivec + 12, ctr32);
- /* ... overflow was detected, propogate carry. */
- if (ctr32 == 0) {
- ctr96_inc(ivec);
- }
- blocks *= 16;
- len -= blocks;
- out += blocks;
- in += blocks;
- }
- if (len) {
- memset(ecount_buf, 0, 16);
- (*func)(ecount_buf, ecount_buf, 1, key, ivec);
- ++ctr32;
- PUTU32(ivec + 12, ctr32);
- if (ctr32 == 0) {
- ctr96_inc(ivec);
- }
- while (len--) {
- out[n] = in[n] ^ ecount_buf[n];
- ++n;
- }
- }
-
- *num = n;
- }
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