1 /*
2 * Copyright 2008-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <string.h>
11 #include <openssl/crypto.h>
12 #include "crypto/modes.h"
13
14 #if defined(__GNUC__) && !defined(STRICT_ALIGNMENT)
15 typedef size_t size_t_aX __attribute((__aligned__(1)));
16 #else
17 typedef size_t size_t_aX;
18 #endif
19
20 /*
21 * The input and output encrypted as though 128bit cfb mode is being used.
22 * The extra state information to record how much of the 128bit block we have
23 * used is contained in *num;
24 */
CRYPTO_cfb128_encrypt(const unsigned char * in,unsigned char * out,size_t len,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)25 void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
26 size_t len, const void *key,
27 unsigned char ivec[16], int *num,
28 int enc, block128_f block)
29 {
30 unsigned int n;
31 size_t l = 0;
32
33 if (*num < 0) {
34 /* There is no good way to signal an error return from here */
35 *num = -1;
36 return;
37 }
38 n = *num;
39
40 if (enc) {
41 #if !defined(OPENSSL_SMALL_FOOTPRINT)
42 if (16 % sizeof(size_t) == 0) { /* always true actually */
43 do {
44 while (n && len) {
45 *(out++) = ivec[n] ^= *(in++);
46 --len;
47 n = (n + 1) % 16;
48 }
49 # if defined(STRICT_ALIGNMENT)
50 if (((size_t)in | (size_t)out | (size_t)ivec) %
51 sizeof(size_t) != 0)
52 break;
53 # endif
54 while (len >= 16) {
55 (*block) (ivec, ivec, key);
56 for (; n < 16; n += sizeof(size_t)) {
57 *(size_t_aX *)(out + n) =
58 *(size_t_aX *)(ivec + n)
59 ^= *(size_t_aX *)(in + n);
60 }
61 len -= 16;
62 out += 16;
63 in += 16;
64 n = 0;
65 }
66 if (len) {
67 (*block) (ivec, ivec, key);
68 while (len--) {
69 out[n] = ivec[n] ^= in[n];
70 ++n;
71 }
72 }
73 *num = n;
74 return;
75 } while (0);
76 }
77 /* the rest would be commonly eliminated by x86* compiler */
78 #endif
79 while (l < len) {
80 if (n == 0) {
81 (*block) (ivec, ivec, key);
82 }
83 out[l] = ivec[n] ^= in[l];
84 ++l;
85 n = (n + 1) % 16;
86 }
87 *num = n;
88 } else {
89 #if !defined(OPENSSL_SMALL_FOOTPRINT)
90 if (16 % sizeof(size_t) == 0) { /* always true actually */
91 do {
92 while (n && len) {
93 unsigned char c;
94 *(out++) = ivec[n] ^ (c = *(in++));
95 ivec[n] = c;
96 --len;
97 n = (n + 1) % 16;
98 }
99 # if defined(STRICT_ALIGNMENT)
100 if (((size_t)in | (size_t)out | (size_t)ivec) %
101 sizeof(size_t) != 0)
102 break;
103 # endif
104 while (len >= 16) {
105 (*block) (ivec, ivec, key);
106 for (; n < 16; n += sizeof(size_t)) {
107 size_t t = *(size_t_aX *)(in + n);
108 *(size_t_aX *)(out + n)
109 = *(size_t_aX *)(ivec + n) ^ t;
110 *(size_t_aX *)(ivec + n) = t;
111 }
112 len -= 16;
113 out += 16;
114 in += 16;
115 n = 0;
116 }
117 if (len) {
118 (*block) (ivec, ivec, key);
119 while (len--) {
120 unsigned char c;
121 out[n] = ivec[n] ^ (c = in[n]);
122 ivec[n] = c;
123 ++n;
124 }
125 }
126 *num = n;
127 return;
128 } while (0);
129 }
130 /* the rest would be commonly eliminated by x86* compiler */
131 #endif
132 while (l < len) {
133 unsigned char c;
134 if (n == 0) {
135 (*block) (ivec, ivec, key);
136 }
137 out[l] = ivec[n] ^ (c = in[l]);
138 ivec[n] = c;
139 ++l;
140 n = (n + 1) % 16;
141 }
142 *num = n;
143 }
144 }
145
146 /*
147 * This expects a single block of size nbits for both in and out. Note that
148 * it corrupts any extra bits in the last byte of out
149 */
cfbr_encrypt_block(const unsigned char * in,unsigned char * out,int nbits,const void * key,unsigned char ivec[16],int enc,block128_f block)150 static void cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
151 int nbits, const void *key,
152 unsigned char ivec[16], int enc,
153 block128_f block)
154 {
155 int n, rem, num;
156 unsigned char ovec[16 * 2 + 1]; /* +1 because we dereference (but don't
157 * use) one byte off the end */
158
159 if (nbits <= 0 || nbits > 128)
160 return;
161
162 /* fill in the first half of the new IV with the current IV */
163 memcpy(ovec, ivec, 16);
164 /* construct the new IV */
165 (*block) (ivec, ivec, key);
166 num = (nbits + 7) / 8;
167 if (enc) /* encrypt the input */
168 for (n = 0; n < num; ++n)
169 out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
170 else /* decrypt the input */
171 for (n = 0; n < num; ++n)
172 out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
173 /* shift ovec left... */
174 rem = nbits % 8;
175 num = nbits / 8;
176 if (rem == 0)
177 memcpy(ivec, ovec + num, 16);
178 else
179 for (n = 0; n < 16; ++n)
180 ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);
181
182 /* it is not necessary to cleanse ovec, since the IV is not secret */
183 }
184
185 /* N.B. This expects the input to be packed, MS bit first */
CRYPTO_cfb128_1_encrypt(const unsigned char * in,unsigned char * out,size_t bits,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)186 void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
187 size_t bits, const void *key,
188 unsigned char ivec[16], int *num,
189 int enc, block128_f block)
190 {
191 size_t n;
192 unsigned char c[1], d[1];
193
194 for (n = 0; n < bits; ++n) {
195 c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
196 cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
197 out[n / 8] = (out[n / 8] & ~(1 << (unsigned int)(7 - n % 8))) |
198 ((d[0] & 0x80) >> (unsigned int)(n % 8));
199 }
200 }
201
CRYPTO_cfb128_8_encrypt(const unsigned char * in,unsigned char * out,size_t length,const void * key,unsigned char ivec[16],int * num,int enc,block128_f block)202 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
203 size_t length, const void *key,
204 unsigned char ivec[16], int *num,
205 int enc, block128_f block)
206 {
207 size_t n;
208
209 for (n = 0; n < length; ++n)
210 cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
211 }
212