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) % sizeof(size_t) != 0)
51 break;
52 #endif
53 while (len >= 16) {
54 (*block)(ivec, ivec, key);
55 for (; n < 16; n += sizeof(size_t)) {
56 *(size_t_aX *)(out + n) = *(size_t_aX *)(ivec + n)
57 ^= *(size_t_aX *)(in + n);
58 }
59 len -= 16;
60 out += 16;
61 in += 16;
62 n = 0;
63 }
64 if (len) {
65 (*block)(ivec, ivec, key);
66 while (len--) {
67 out[n] = ivec[n] ^= in[n];
68 ++n;
69 }
70 }
71 *num = n;
72 return;
73 } while (0);
74 }
75 /* the rest would be commonly eliminated by x86* compiler */
76 #endif
77 while (l < len) {
78 if (n == 0) {
79 (*block)(ivec, ivec, key);
80 }
81 out[l] = ivec[n] ^= in[l];
82 ++l;
83 n = (n + 1) % 16;
84 }
85 *num = n;
86 } else {
87 #if !defined(OPENSSL_SMALL_FOOTPRINT)
88 if (16 % sizeof(size_t) == 0) { /* always true actually */
89 do {
90 while (n && len) {
91 unsigned char c;
92 *(out++) = ivec[n] ^ (c = *(in++));
93 ivec[n] = c;
94 --len;
95 n = (n + 1) % 16;
96 }
97 #if defined(STRICT_ALIGNMENT)
98 if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0)
99 break;
100 #endif
101 while (len >= 16) {
102 (*block)(ivec, ivec, key);
103 for (; n < 16; n += sizeof(size_t)) {
104 size_t t = *(size_t_aX *)(in + n);
105 *(size_t_aX *)(out + n)
106 = *(size_t_aX *)(ivec + n) ^ t;
107 *(size_t_aX *)(ivec + n) = t;
108 }
109 len -= 16;
110 out += 16;
111 in += 16;
112 n = 0;
113 }
114 if (len) {
115 (*block)(ivec, ivec, key);
116 while (len--) {
117 unsigned char c;
118 out[n] = ivec[n] ^ (c = in[n]);
119 ivec[n] = c;
120 ++n;
121 }
122 }
123 *num = n;
124 return;
125 } while (0);
126 }
127 /* the rest would be commonly eliminated by x86* compiler */
128 #endif
129 while (l < len) {
130 unsigned char c;
131 if (n == 0) {
132 (*block)(ivec, ivec, key);
133 }
134 out[l] = ivec[n] ^ (c = in[l]);
135 ivec[n] = c;
136 ++l;
137 n = (n + 1) % 16;
138 }
139 *num = n;
140 }
141 }
142
143 /*
144 * This expects a single block of size nbits for both in and out. Note that
145 * it corrupts any extra bits in the last byte of out
146 */
cfbr_encrypt_block(const unsigned char * in,unsigned char * out,int nbits,const void * key,unsigned char ivec[16],int enc,block128_f block)147 static void cfbr_encrypt_block(const unsigned char *in, unsigned char *out,
148 int nbits, const void *key,
149 unsigned char ivec[16], int enc,
150 block128_f block)
151 {
152 int n, rem, num;
153 unsigned char ovec[16 * 2 + 1]; /* +1 because we dereference (but don't
154 * use) one byte off the end */
155
156 if (nbits <= 0 || nbits > 128)
157 return;
158
159 /* fill in the first half of the new IV with the current IV */
160 memcpy(ovec, ivec, 16);
161 /* construct the new IV */
162 (*block)(ivec, ivec, key);
163 num = (nbits + 7) / 8;
164 if (enc) /* encrypt the input */
165 for (n = 0; n < num; ++n)
166 out[n] = (ovec[16 + n] = in[n] ^ ivec[n]);
167 else /* decrypt the input */
168 for (n = 0; n < num; ++n)
169 out[n] = (ovec[16 + n] = in[n]) ^ ivec[n];
170 /* shift ovec left... */
171 rem = nbits % 8;
172 num = nbits / 8;
173 if (rem == 0)
174 memcpy(ivec, ovec + num, 16);
175 else
176 for (n = 0; n < 16; ++n)
177 ivec[n] = ovec[n + num] << rem | ovec[n + num + 1] >> (8 - rem);
178
179 /* it is not necessary to cleanse ovec, since the IV is not secret */
180 }
181
182 /* 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)183 void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
184 size_t bits, const void *key,
185 unsigned char ivec[16], int *num,
186 int enc, block128_f block)
187 {
188 size_t n;
189 unsigned char c[1], d[1];
190
191 for (n = 0; n < bits; ++n) {
192 c[0] = (in[n / 8] & (1 << (7 - n % 8))) ? 0x80 : 0;
193 cfbr_encrypt_block(c, d, 1, key, ivec, enc, block);
194 out[n / 8] = (out[n / 8] & ~(1 << (unsigned int)(7 - n % 8))) | ((d[0] & 0x80) >> (unsigned int)(n % 8));
195 }
196 }
197
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)198 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
199 size_t length, const void *key,
200 unsigned char ivec[16], int *num,
201 int enc, block128_f block)
202 {
203 size_t n;
204
205 for (n = 0; n < length; ++n)
206 cfbr_encrypt_block(&in[n], &out[n], 8, key, ivec, enc, block);
207 }
208