1 /* $OpenBSD: cmac.c,v 1.11 2021/12/12 21:30:13 tb Exp $ */
2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3 * project.
4 */
5 /* ====================================================================
6 * Copyright (c) 2010 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * licensing@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 */
53
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57
58 #include <openssl/cmac.h>
59
60 #include "evp_locl.h"
61
62 struct CMAC_CTX_st {
63 /* Cipher context to use */
64 EVP_CIPHER_CTX cctx;
65 /* Keys k1 and k2 */
66 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
67 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
68 /* Temporary block */
69 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
70 /* Last (possibly partial) block */
71 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
72 /* Number of bytes in last block: -1 means context not initialised */
73 int nlast_block;
74 };
75
76
77 /* Make temporary keys K1 and K2 */
78
79 static void
make_kn(unsigned char * k1,unsigned char * l,int bl)80 make_kn(unsigned char *k1, unsigned char *l, int bl)
81 {
82 int i;
83
84 /* Shift block to left, including carry */
85 for (i = 0; i < bl; i++) {
86 k1[i] = l[i] << 1;
87 if (i < bl - 1 && l[i + 1] & 0x80)
88 k1[i] |= 1;
89 }
90 /* If MSB set fixup with R */
91 if (l[0] & 0x80)
92 k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
93 }
94
95 CMAC_CTX *
CMAC_CTX_new(void)96 CMAC_CTX_new(void)
97 {
98 CMAC_CTX *ctx;
99
100 ctx = malloc(sizeof(CMAC_CTX));
101 if (!ctx)
102 return NULL;
103 EVP_CIPHER_CTX_init(&ctx->cctx);
104 ctx->nlast_block = -1;
105 return ctx;
106 }
107
108 void
CMAC_CTX_cleanup(CMAC_CTX * ctx)109 CMAC_CTX_cleanup(CMAC_CTX *ctx)
110 {
111 EVP_CIPHER_CTX_cleanup(&ctx->cctx);
112 explicit_bzero(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
113 explicit_bzero(ctx->k1, EVP_MAX_BLOCK_LENGTH);
114 explicit_bzero(ctx->k2, EVP_MAX_BLOCK_LENGTH);
115 explicit_bzero(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
116 ctx->nlast_block = -1;
117 }
118
119 EVP_CIPHER_CTX *
CMAC_CTX_get0_cipher_ctx(CMAC_CTX * ctx)120 CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
121 {
122 return &ctx->cctx;
123 }
124
125 void
CMAC_CTX_free(CMAC_CTX * ctx)126 CMAC_CTX_free(CMAC_CTX *ctx)
127 {
128 if (ctx == NULL)
129 return;
130
131 CMAC_CTX_cleanup(ctx);
132 free(ctx);
133 }
134
135 int
CMAC_CTX_copy(CMAC_CTX * out,const CMAC_CTX * in)136 CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
137 {
138 int bl;
139
140 if (in->nlast_block == -1)
141 return 0;
142 if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
143 return 0;
144 bl = EVP_CIPHER_CTX_block_size(&in->cctx);
145 memcpy(out->k1, in->k1, bl);
146 memcpy(out->k2, in->k2, bl);
147 memcpy(out->tbl, in->tbl, bl);
148 memcpy(out->last_block, in->last_block, bl);
149 out->nlast_block = in->nlast_block;
150 return 1;
151 }
152
153 int
CMAC_Init(CMAC_CTX * ctx,const void * key,size_t keylen,const EVP_CIPHER * cipher,ENGINE * impl)154 CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
155 const EVP_CIPHER *cipher, ENGINE *impl)
156 {
157 static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
158
159 /* All zeros means restart */
160 if (!key && !cipher && !impl && keylen == 0) {
161 /* Not initialised */
162 if (ctx->nlast_block == -1)
163 return 0;
164 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
165 return 0;
166 memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
167 ctx->nlast_block = 0;
168 return 1;
169 }
170 /* Initialiase context */
171 if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
172 return 0;
173 /* Non-NULL key means initialisation complete */
174 if (key) {
175 int bl;
176
177 if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
178 return 0;
179 if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
180 return 0;
181 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
182 return 0;
183 bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
184 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
185 return 0;
186 make_kn(ctx->k1, ctx->tbl, bl);
187 make_kn(ctx->k2, ctx->k1, bl);
188 explicit_bzero(ctx->tbl, bl);
189 /* Reset context again ready for first data block */
190 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
191 return 0;
192 /* Zero tbl so resume works */
193 memset(ctx->tbl, 0, bl);
194 ctx->nlast_block = 0;
195 }
196 return 1;
197 }
198
199 int
CMAC_Update(CMAC_CTX * ctx,const void * in,size_t dlen)200 CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
201 {
202 const unsigned char *data = in;
203 size_t bl;
204
205 if (ctx->nlast_block == -1)
206 return 0;
207 if (dlen == 0)
208 return 1;
209 bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
210 /* Copy into partial block if we need to */
211 if (ctx->nlast_block > 0) {
212 size_t nleft;
213
214 nleft = bl - ctx->nlast_block;
215 if (dlen < nleft)
216 nleft = dlen;
217 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
218 dlen -= nleft;
219 ctx->nlast_block += nleft;
220 /* If no more to process return */
221 if (dlen == 0)
222 return 1;
223 data += nleft;
224 /* Else not final block so encrypt it */
225 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block, bl))
226 return 0;
227 }
228 /* Encrypt all but one of the complete blocks left */
229 while (dlen > bl) {
230 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
231 return 0;
232 dlen -= bl;
233 data += bl;
234 }
235 /* Copy any data left to last block buffer */
236 memcpy(ctx->last_block, data, dlen);
237 ctx->nlast_block = dlen;
238 return 1;
239 }
240
241 int
CMAC_Final(CMAC_CTX * ctx,unsigned char * out,size_t * poutlen)242 CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
243 {
244 int i, bl, lb;
245
246 if (ctx->nlast_block == -1)
247 return 0;
248 bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
249 *poutlen = (size_t)bl;
250 if (!out)
251 return 1;
252 lb = ctx->nlast_block;
253 /* Is last block complete? */
254 if (lb == bl) {
255 for (i = 0; i < bl; i++)
256 out[i] = ctx->last_block[i] ^ ctx->k1[i];
257 } else {
258 ctx->last_block[lb] = 0x80;
259 if (bl - lb > 1)
260 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
261 for (i = 0; i < bl; i++)
262 out[i] = ctx->last_block[i] ^ ctx->k2[i];
263 }
264 if (!EVP_Cipher(&ctx->cctx, out, out, bl)) {
265 explicit_bzero(out, bl);
266 return 0;
267 }
268 return 1;
269 }
270
271 int
CMAC_resume(CMAC_CTX * ctx)272 CMAC_resume(CMAC_CTX *ctx)
273 {
274 if (ctx->nlast_block == -1)
275 return 0;
276 /* The buffer "tbl" containes the last fully encrypted block
277 * which is the last IV (or all zeroes if no last encrypted block).
278 * The last block has not been modified since CMAC_final().
279 * So reinitialising using the last decrypted block will allow
280 * CMAC to continue after calling CMAC_Final().
281 */
282 return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
283 }
284