123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139 |
- /* crypto/aes/aes_ctr.c -*- mode:C; c-file-style: "eay" -*- */
- /* ====================================================================
- * Copyright (c) 1998-2002 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.
- * ====================================================================
- *
- */
- #ifndef AES_DEBUG
- # ifndef NDEBUG
- # define NDEBUG
- # endif
- #endif
- #include <assert.h>
- #include <openssl/aes.h>
- #include "aes_locl.h"
- /* NOTE: the IV/counter CTR mode is big-endian. The rest of the AES code
- * is endian-neutral. */
- /* increment counter (128-bit int) by 1 */
- static void AES_ctr128_inc(unsigned char *counter) {
- unsigned long c;
- /* Grab bottom dword of counter and increment */
- c = GETU32(counter + 12);
- c++; c &= 0xFFFFFFFF;
- PUTU32(counter + 12, c);
- /* if no overflow, we're done */
- if (c)
- return;
- /* Grab 1st dword of counter and increment */
- c = GETU32(counter + 8);
- c++; c &= 0xFFFFFFFF;
- PUTU32(counter + 8, c);
- /* if no overflow, we're done */
- if (c)
- return;
- /* Grab 2nd dword of counter and increment */
- c = GETU32(counter + 4);
- c++; c &= 0xFFFFFFFF;
- PUTU32(counter + 4, c);
- /* if no overflow, we're done */
- if (c)
- return;
- /* Grab top dword of counter and increment */
- c = GETU32(counter + 0);
- c++; c &= 0xFFFFFFFF;
- PUTU32(counter + 0, c);
- }
- /* 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 AES_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 AES_ctr128_encrypt(const unsigned char *in, unsigned char *out,
- const unsigned long length, const AES_KEY *key,
- unsigned char ivec[AES_BLOCK_SIZE],
- unsigned char ecount_buf[AES_BLOCK_SIZE],
- unsigned int *num) {
- unsigned int n;
- unsigned long l=length;
- assert(in && out && key && counter && num);
- assert(*num < AES_BLOCK_SIZE);
- n = *num;
- while (l--) {
- if (n == 0) {
- AES_encrypt(ivec, ecount_buf, key);
- AES_ctr128_inc(ivec);
- }
- *(out++) = *(in++) ^ ecount_buf[n];
- n = (n+1) % AES_BLOCK_SIZE;
- }
- *num=n;
- }
|