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 <openssl/crypto.h>
52#include "modes_lcl.h"
53#include <string.h>
54
55#ifndef MODES_DEBUG
56# ifndef NDEBUG
57#  define NDEBUG
58# endif
59#endif
60#include <assert.h>
61
62/* The input and output encrypted as though 128bit cfb mode is being
63 * used.  The extra state information to record how much of the
64 * 128bit block we have used is contained in *num;
65 */
66void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
67			size_t len, const void *key,
68			unsigned char ivec[16], int *num,
69			int enc, block128_f block)
70{
71    unsigned int n;
72    size_t l = 0;
73
74    assert(in && out && key && ivec && num);
75
76    n = *num;
77
78    if (enc) {
79#if !defined(OPENSSL_SMALL_FOOTPRINT)
80	if (16%sizeof(size_t) == 0) do {	/* always true actually */
81		while (n && len) {
82			*(out++) = ivec[n] ^= *(in++);
83			--len;
84			n = (n+1) % 16;
85		}
86#if defined(STRICT_ALIGNMENT)
87		if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
88			break;
89#endif
90		while (len>=16) {
91			(*block)(ivec, ivec, key);
92			for (; n<16; n+=sizeof(size_t)) {
93				*(size_t*)(out+n) =
94				*(size_t*)(ivec+n) ^= *(size_t*)(in+n);
95			}
96			len -= 16;
97			out += 16;
98			in  += 16;
99			n = 0;
100		}
101		if (len) {
102			(*block)(ivec, ivec, key);
103			while (len--) {
104				out[n] = ivec[n] ^= in[n];
105				++n;
106			}
107		}
108		*num = n;
109		return;
110	} while (0);
111	/* the rest would be commonly eliminated by x86* compiler */
112#endif
113	while (l<len) {
114		if (n == 0) {
115			(*block)(ivec, ivec, key);
116		}
117		out[l] = ivec[n] ^= in[l];
118		++l;
119		n = (n+1) % 16;
120	}
121	*num = n;
122    } else {
123#if !defined(OPENSSL_SMALL_FOOTPRINT)
124	if (16%sizeof(size_t) == 0) do {	/* always true actually */
125		while (n && len) {
126			unsigned char c;
127			*(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
128			--len;
129			n = (n+1) % 16;
130 		}
131#if defined(STRICT_ALIGNMENT)
132		if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
133			break;
134#endif
135		while (len>=16) {
136			(*block)(ivec, ivec, key);
137			for (; n<16; n+=sizeof(size_t)) {
138				size_t t = *(size_t*)(in+n);
139				*(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t;
140				*(size_t*)(ivec+n) = t;
141			}
142			len -= 16;
143			out += 16;
144			in  += 16;
145			n = 0;
146		}
147		if (len) {
148			(*block)(ivec, ivec, key);
149			while (len--) {
150				unsigned char c;
151				out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c;
152				++n;
153			}
154 		}
155		*num = n;
156		return;
157	} while (0);
158	/* the rest would be commonly eliminated by x86* compiler */
159#endif
160	while (l<len) {
161		unsigned char c;
162		if (n == 0) {
163			(*block)(ivec, ivec, key);
164		}
165		out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
166		++l;
167		n = (n+1) % 16;
168	}
169	*num=n;
170    }
171}
172
173/* This expects a single block of size nbits for both in and out. Note that
174   it corrupts any extra bits in the last byte of out */
175static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
176			    int nbits,const void *key,
177			    unsigned char ivec[16],int enc,
178			    block128_f block)
179{
180    int n,rem,num;
181    unsigned char ovec[16*2 + 1];  /* +1 because we dererefence (but don't use) one byte off the end */
182
183    if (nbits<=0 || nbits>128) return;
184
185	/* fill in the first half of the new IV with the current IV */
186	memcpy(ovec,ivec,16);
187	/* construct the new IV */
188	(*block)(ivec,ivec,key);
189	num = (nbits+7)/8;
190	if (enc)	/* encrypt the input */
191	    for(n=0 ; n < num ; ++n)
192		out[n] = (ovec[16+n] = in[n] ^ ivec[n]);
193	else		/* decrypt the input */
194	    for(n=0 ; n < num ; ++n)
195		out[n] = (ovec[16+n] = in[n]) ^ ivec[n];
196	/* shift ovec left... */
197	rem = nbits%8;
198	num = nbits/8;
199	if(rem==0)
200	    memcpy(ivec,ovec+num,16);
201	else
202	    for(n=0 ; n < 16 ; ++n)
203		ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
204
205    /* it is not necessary to cleanse ovec, since the IV is not secret */
206}
207
208/* N.B. This expects the input to be packed, MS bit first */
209void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
210		 	size_t bits, const void *key,
211			unsigned char ivec[16], int *num,
212			int enc, block128_f block)
213{
214    size_t n;
215    unsigned char c[1],d[1];
216
217    assert(in && out && key && ivec && num);
218    assert(*num == 0);
219
220    for(n=0 ; n<bits ; ++n)
221	{
222	c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
223	cfbr_encrypt_block(c,d,1,key,ivec,enc,block);
224	out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) |
225		 ((d[0]&0x80) >> (unsigned int)(n%8));
226	}
227}
228
229void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
230			size_t length, const void *key,
231			unsigned char ivec[16], int *num,
232			int enc, block128_f block)
233{
234    size_t n;
235
236    assert(in && out && key && ivec && num);
237    assert(*num == 0);
238
239    for(n=0 ; n<length ; ++n)
240	cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block);
241}
242
243