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@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 cfb 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 */
73void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
74			size_t len, const void *key,
75			unsigned char ivec[16], int *num,
76			int enc, 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 (enc) {
86#if !defined(OPENSSL_SMALL_FOOTPRINT)
87	if (16%sizeof(size_t) == 0) do {	/* always true actually */
88		while (n && len) {
89			*(out++) = ivec[n] ^= *(in++);
90			--len;
91			n = (n+1) % 16;
92		}
93#if defined(STRICT_ALIGNMENT)
94		if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
95			break;
96#endif
97		while (len>=16) {
98			(*block)(ivec, ivec, key);
99			for (; n<16; n+=sizeof(size_t)) {
100				*(size_t*)(out+n) =
101				*(size_t*)(ivec+n) ^= *(size_t*)(in+n);
102			}
103			len -= 16;
104			out += 16;
105			in  += 16;
106			n = 0;
107		}
108		if (len) {
109			(*block)(ivec, ivec, key);
110			while (len--) {
111				out[n] = ivec[n] ^= in[n];
112				++n;
113			}
114		}
115		*num = n;
116		return;
117	} while (0);
118	/* the rest would be commonly eliminated by x86* compiler */
119#endif
120	while (l<len) {
121		if (n == 0) {
122			(*block)(ivec, ivec, key);
123		}
124		out[l] = ivec[n] ^= in[l];
125		++l;
126		n = (n+1) % 16;
127	}
128	*num = n;
129    } else {
130#if !defined(OPENSSL_SMALL_FOOTPRINT)
131	if (16%sizeof(size_t) == 0) do {	/* always true actually */
132		while (n && len) {
133			unsigned char c;
134			*(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
135			--len;
136			n = (n+1) % 16;
137 		}
138#if defined(STRICT_ALIGNMENT)
139		if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
140			break;
141#endif
142		while (len>=16) {
143			(*block)(ivec, ivec, key);
144			for (; n<16; n+=sizeof(size_t)) {
145				size_t t = *(size_t*)(in+n);
146				*(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t;
147				*(size_t*)(ivec+n) = t;
148			}
149			len -= 16;
150			out += 16;
151			in  += 16;
152			n = 0;
153		}
154		if (len) {
155			(*block)(ivec, ivec, key);
156			while (len--) {
157				unsigned char c;
158				out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c;
159				++n;
160			}
161 		}
162		*num = n;
163		return;
164	} while (0);
165	/* the rest would be commonly eliminated by x86* compiler */
166#endif
167	while (l<len) {
168		unsigned char c;
169		if (n == 0) {
170			(*block)(ivec, ivec, key);
171		}
172		out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
173		++l;
174		n = (n+1) % 16;
175	}
176	*num=n;
177    }
178}
179
180/* This expects a single block of size nbits for both in and out. Note that
181   it corrupts any extra bits in the last byte of out */
182static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
183			    int nbits,const void *key,
184			    unsigned char ivec[16],int enc,
185			    block128_f block)
186{
187    int n,rem,num;
188    unsigned char ovec[16*2 + 1];  /* +1 because we dererefence (but don't use) one byte off the end */
189
190    if (nbits<=0 || nbits>128) return;
191
192	/* fill in the first half of the new IV with the current IV */
193	memcpy(ovec,ivec,16);
194	/* construct the new IV */
195	(*block)(ivec,ivec,key);
196	num = (nbits+7)/8;
197	if (enc)	/* encrypt the input */
198	    for(n=0 ; n < num ; ++n)
199		out[n] = (ovec[16+n] = in[n] ^ ivec[n]);
200	else		/* decrypt the input */
201	    for(n=0 ; n < num ; ++n)
202		out[n] = (ovec[16+n] = in[n]) ^ ivec[n];
203	/* shift ovec left... */
204	rem = nbits%8;
205	num = nbits/8;
206	if(rem==0)
207	    memcpy(ivec,ovec+num,16);
208	else
209	    for(n=0 ; n < 16 ; ++n)
210		ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
211
212    /* it is not necessary to cleanse ovec, since the IV is not secret */
213}
214
215/* N.B. This expects the input to be packed, MS bit first */
216void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
217		 	size_t bits, const void *key,
218			unsigned char ivec[16], int *num,
219			int enc, block128_f block)
220{
221    size_t n;
222    unsigned char c[1],d[1];
223
224    assert(in && out && key && ivec && num);
225    assert(*num == 0);
226
227    for(n=0 ; n<bits ; ++n)
228	{
229	c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
230	cfbr_encrypt_block(c,d,1,key,ivec,enc,block);
231	out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) |
232		 ((d[0]&0x80) >> (unsigned int)(n%8));
233	}
234}
235
236void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
237			size_t length, const void *key,
238			unsigned char ivec[16], int *num,
239			int enc, block128_f block)
240{
241    size_t n;
242
243    assert(in && out && key && ivec && num);
244    assert(*num == 0);
245
246    for(n=0 ; n<length ; ++n)
247	cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block);
248}
249
250