1 /*
2 * Copyright 2010-2022 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 /*
11 * CMAC low level APIs are deprecated for public use, but still ok for internal
12 * use.
13 */
14 #include "internal/deprecated.h"
15
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <string.h>
19 #include "internal/cryptlib.h"
20 #include <openssl/cmac.h>
21 #include <openssl/err.h>
22
23 struct CMAC_CTX_st {
24 /* Cipher context to use */
25 EVP_CIPHER_CTX *cctx;
26 /* Keys k1 and k2 */
27 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
28 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
29 /* Temporary block */
30 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
31 /* Last (possibly partial) block */
32 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
33 /* Number of bytes in last block: -1 means context not initialised */
34 int nlast_block;
35 };
36
37 /* Make temporary keys K1 and K2 */
38
make_kn(unsigned char * k1,const unsigned char * l,int bl)39 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
40 {
41 int i;
42 unsigned char c = l[0], carry = c >> 7, cnext;
43
44 /* Shift block to left, including carry */
45 for (i = 0; i < bl - 1; i++, c = cnext)
46 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
47
48 /* If MSB set fixup with R */
49 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
50 }
51
CMAC_CTX_new(void)52 CMAC_CTX *CMAC_CTX_new(void)
53 {
54 CMAC_CTX *ctx;
55
56 if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) {
57 ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
58 return NULL;
59 }
60 ctx->cctx = EVP_CIPHER_CTX_new();
61 if (ctx->cctx == NULL) {
62 OPENSSL_free(ctx);
63 return NULL;
64 }
65 ctx->nlast_block = -1;
66 return ctx;
67 }
68
CMAC_CTX_cleanup(CMAC_CTX * ctx)69 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
70 {
71 EVP_CIPHER_CTX_reset(ctx->cctx);
72 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
73 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
74 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
75 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
76 ctx->nlast_block = -1;
77 }
78
CMAC_CTX_get0_cipher_ctx(CMAC_CTX * ctx)79 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
80 {
81 return ctx->cctx;
82 }
83
CMAC_CTX_free(CMAC_CTX * ctx)84 void CMAC_CTX_free(CMAC_CTX *ctx)
85 {
86 if (!ctx)
87 return;
88 CMAC_CTX_cleanup(ctx);
89 EVP_CIPHER_CTX_free(ctx->cctx);
90 OPENSSL_free(ctx);
91 }
92
CMAC_CTX_copy(CMAC_CTX * out,const CMAC_CTX * in)93 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
94 {
95 int bl;
96
97 if (in->nlast_block == -1)
98 return 0;
99 if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) < 0)
100 return 0;
101 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
102 return 0;
103 memcpy(out->k1, in->k1, bl);
104 memcpy(out->k2, in->k2, bl);
105 memcpy(out->tbl, in->tbl, bl);
106 memcpy(out->last_block, in->last_block, bl);
107 out->nlast_block = in->nlast_block;
108 return 1;
109 }
110
CMAC_Init(CMAC_CTX * ctx,const void * key,size_t keylen,const EVP_CIPHER * cipher,ENGINE * impl)111 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
112 const EVP_CIPHER *cipher, ENGINE *impl)
113 {
114 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
115
116 /* All zeros means restart */
117 if (!key && !cipher && !impl && keylen == 0) {
118 /* Not initialised */
119 if (ctx->nlast_block == -1)
120 return 0;
121 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
122 return 0;
123 memset(ctx->tbl, 0, EVP_CIPHER_CTX_get_block_size(ctx->cctx));
124 ctx->nlast_block = 0;
125 return 1;
126 }
127 /* Initialise context */
128 if (cipher != NULL) {
129 /* Ensure we can't use this ctx until we also have a key */
130 ctx->nlast_block = -1;
131 if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
132 return 0;
133 }
134 /* Non-NULL key means initialisation complete */
135 if (key != NULL) {
136 int bl;
137
138 /* If anything fails then ensure we can't use this ctx */
139 ctx->nlast_block = -1;
140 if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
141 return 0;
142 if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
143 return 0;
144 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
145 return 0;
146 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
147 return 0;
148 if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
149 return 0;
150 make_kn(ctx->k1, ctx->tbl, bl);
151 make_kn(ctx->k2, ctx->k1, bl);
152 OPENSSL_cleanse(ctx->tbl, bl);
153 /* Reset context again ready for first data block */
154 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
155 return 0;
156 /* Zero tbl so resume works */
157 memset(ctx->tbl, 0, bl);
158 ctx->nlast_block = 0;
159 }
160 return 1;
161 }
162
CMAC_Update(CMAC_CTX * ctx,const void * in,size_t dlen)163 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
164 {
165 const unsigned char *data = in;
166 int bl;
167
168 if (ctx->nlast_block == -1)
169 return 0;
170 if (dlen == 0)
171 return 1;
172 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
173 return 0;
174 /* Copy into partial block if we need to */
175 if (ctx->nlast_block > 0) {
176 size_t nleft;
177
178 nleft = bl - ctx->nlast_block;
179 if (dlen < nleft)
180 nleft = dlen;
181 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
182 dlen -= nleft;
183 ctx->nlast_block += nleft;
184 /* If no more to process return */
185 if (dlen == 0)
186 return 1;
187 data += nleft;
188 /* Else not final block so encrypt it */
189 if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
190 return 0;
191 }
192 /* Encrypt all but one of the complete blocks left */
193 while (dlen > (size_t)bl) {
194 if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
195 return 0;
196 dlen -= bl;
197 data += bl;
198 }
199 /* Copy any data left to last block buffer */
200 memcpy(ctx->last_block, data, dlen);
201 ctx->nlast_block = dlen;
202 return 1;
203
204 }
205
CMAC_Final(CMAC_CTX * ctx,unsigned char * out,size_t * poutlen)206 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
207 {
208 int i, bl, lb;
209
210 if (ctx->nlast_block == -1)
211 return 0;
212 if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
213 return 0;
214 if (poutlen != NULL)
215 *poutlen = (size_t)bl;
216 if (!out)
217 return 1;
218 lb = ctx->nlast_block;
219 /* Is last block complete? */
220 if (lb == bl) {
221 for (i = 0; i < bl; i++)
222 out[i] = ctx->last_block[i] ^ ctx->k1[i];
223 } else {
224 ctx->last_block[lb] = 0x80;
225 if (bl - lb > 1)
226 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
227 for (i = 0; i < bl; i++)
228 out[i] = ctx->last_block[i] ^ ctx->k2[i];
229 }
230 if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
231 OPENSSL_cleanse(out, bl);
232 return 0;
233 }
234 return 1;
235 }
236
CMAC_resume(CMAC_CTX * ctx)237 int CMAC_resume(CMAC_CTX *ctx)
238 {
239 if (ctx->nlast_block == -1)
240 return 0;
241 /*
242 * The buffer "tbl" contains the last fully encrypted block which is the
243 * last IV (or all zeroes if no last encrypted block). The last block has
244 * not been modified since CMAC_final(). So reinitialising using the last
245 * decrypted block will allow CMAC to continue after calling
246 * CMAC_Final().
247 */
248 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
249 }
250