/* 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;}