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      1 /* ====================================================================
      2  * Copyright (c) 2008 The OpenSSL Project.  All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in
     13  *    the documentation and/or other materials provided with the
     14  *    distribution.
     15  *
     16  * 3. All advertising materials mentioning features or use of this
     17  *    software must display the following acknowledgment:
     18  *    "This product includes software developed by the OpenSSL Project
     19  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
     20  *
     21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
     22  *    endorse or promote products derived from this software without
     23  *    prior written permission. For written permission, please contact
     24  *    openssl-core (at) openssl.org.
     25  *
     26  * 5. Products derived from this software may not be called "OpenSSL"
     27  *    nor may "OpenSSL" appear in their names without prior written
     28  *    permission of the OpenSSL Project.
     29  *
     30  * 6. Redistributions of any form whatsoever must retain the following
     31  *    acknowledgment:
     32  *    "This product includes software developed by the OpenSSL Project
     33  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
     34  *
     35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
     36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
     39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     44  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     45  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     46  * OF THE POSSIBILITY OF SUCH DAMAGE.
     47  * ====================================================================
     48  *
     49  */
     50 
     51 #include "modes.h"
     52 #include <string.h>
     53 
     54 #ifndef MODES_DEBUG
     55 # ifndef NDEBUG
     56 #  define NDEBUG
     57 # endif
     58 #endif
     59 #include <assert.h>
     60 
     61 #define STRICT_ALIGNMENT
     62 #if defined(__i386) || defined(__i386__) || \
     63     defined(__x86_64) || defined(__x86_64__) || \
     64     defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
     65     defined(__s390__) || defined(__s390x__)
     66 #  undef STRICT_ALIGNMENT
     67 #endif
     68 
     69 /* The input and output encrypted as though 128bit ofb mode is being
     70  * used.  The extra state information to record how much of the
     71  * 128bit block we have used is contained in *num;
     72  */
     73 void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out,
     74 			size_t len, const void *key,
     75 			unsigned char ivec[16], int *num,
     76 			block128_f block)
     77 {
     78 	unsigned int n;
     79 	size_t l=0;
     80 
     81 	assert(in && out && key && ivec && num);
     82 
     83 	n = *num;
     84 
     85 #if !defined(OPENSSL_SMALL_FOOTPRINT)
     86 	if (16%sizeof(size_t) == 0) do { /* always true actually */
     87 		while (n && len) {
     88 			*(out++) = *(in++) ^ ivec[n];
     89 			--len;
     90 			n = (n+1) % 16;
     91 		}
     92 #if defined(STRICT_ALIGNMENT)
     93 		if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
     94 			break;
     95 #endif
     96 		while (len>=16) {
     97 			(*block)(ivec, ivec, key);
     98 			for (; n<16; n+=sizeof(size_t))
     99 				*(size_t*)(out+n) =
    100 				*(size_t*)(in+n) ^ *(size_t*)(ivec+n);
    101 			len -= 16;
    102 			out += 16;
    103 			in  += 16;
    104 			n = 0;
    105 		}
    106 		if (len) {
    107 			(*block)(ivec, ivec, key);
    108 			while (len--) {
    109 				out[n] = in[n] ^ ivec[n];
    110 				++n;
    111 			}
    112 		}
    113 		*num = n;
    114 		return;
    115 	} while(0);
    116 	/* the rest would be commonly eliminated by x86* compiler */
    117 #endif
    118 	while (l<len) {
    119 		if (n==0) {
    120 			(*block)(ivec, ivec, key);
    121 		}
    122 		out[l] = in[l] ^ ivec[n];
    123 		++l;
    124 		n = (n+1) % 16;
    125 	}
    126 
    127 	*num=n;
    128 }
    129