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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/crypto.h>
- #include "modes_lcl.h"
- #include <string.h>
- #ifndef MODES_DEBUG
- # ifndef NDEBUG
- # define NDEBUG
- # endif
- #endif
- #include <assert.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(unsigned char *counter) {
- u32 n=16;
- u8 c;
- do {
- --n;
- c = counter[n];
- ++c;
- counter[n] = c;
- if (c) return;
- } while (n);
- }
- #if !defined(OPENSSL_SMALL_FOOTPRINT)
- static void ctr128_inc_aligned(unsigned char *counter) {
- size_t *data,c,n;
- const union { long one; char little; } is_endian = {1};
- if (is_endian.little) {
- ctr128_inc(counter);
- return;
- }
- data = (size_t *)counter;
- n = 16/sizeof(size_t);
- do {
- --n;
- c = data[n];
- ++c;
- data[n] = c;
- if (c) return;
- } while (n);
- }
- #endif
- /* 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
- * responsability for checking that the counter doesn't overflow
- * into the rest of the IV when incremented.
- */
- void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out,
- size_t len, const void *key,
- unsigned char ivec[16], unsigned char ecount_buf[16],
- unsigned int *num, block128_f block)
- {
- unsigned int n;
- size_t l=0;
- assert(in && out && key && ecount_buf && num);
- assert(*num < 16);
- n = *num;
- #if !defined(OPENSSL_SMALL_FOOTPRINT)
- if (16%sizeof(size_t) == 0) do { /* always true actually */
- while (n && len) {
- *(out++) = *(in++) ^ ecount_buf[n];
- --len;
- n = (n+1) % 16;
- }
- #if defined(STRICT_ALIGNMENT)
- if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
- break;
- #endif
- while (len>=16) {
- (*block)(ivec, ecount_buf, key);
- ctr128_inc_aligned(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_aligned(ivec);
- while (len--) {
- out[n] = in[n] ^ ecount_buf[n];
- ++n;
- }
- }
- *num = n;
- return;
- } while(0);
- /* the rest would be commonly eliminated by x86* compiler */
- #endif
- 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;
- }
- /* increment upper 96 bits of 128-bit counter by 1 */
- static void ctr96_inc(unsigned char *counter) {
- u32 n=12;
- u8 c;
- do {
- --n;
- c = counter[n];
- ++c;
- counter[n] = c;
- if (c) return;
- } while (n);
- }
- void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out,
- size_t len, const void *key,
- unsigned char ivec[16], unsigned char 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 += (u32)blocks;
- if (ctr32 < blocks) {
- blocks -= ctr32;
- ctr32 = 0;
- }
- (*func)(in,out,blocks,key,ivec);
- /* (*ctr) 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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