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1 | /* | |
2 | * Copyright 2010-2024 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 | #define LOCAL_BUF_SIZE 2048 | |
24 | struct CMAC_CTX_st { | |
25 | /* Cipher context to use */ | |
26 | EVP_CIPHER_CTX *cctx; | |
27 | /* Keys k1 and k2 */ | |
28 | unsigned char k1[EVP_MAX_BLOCK_LENGTH]; | |
29 | unsigned char k2[EVP_MAX_BLOCK_LENGTH]; | |
30 | /* Temporary block */ | |
31 | unsigned char tbl[EVP_MAX_BLOCK_LENGTH]; | |
32 | /* Last (possibly partial) block */ | |
33 | unsigned char last_block[EVP_MAX_BLOCK_LENGTH]; | |
34 | /* Number of bytes in last block: -1 means context not initialised */ | |
35 | int nlast_block; | |
36 | }; | |
37 | ||
38 | /* Make temporary keys K1 and K2 */ | |
39 | ||
40 | static void make_kn(unsigned char *k1, const unsigned char *l, int bl) | |
41 | { | |
42 | int i; | |
43 | unsigned char c = l[0], carry = c >> 7, cnext; | |
44 | ||
45 | /* Shift block to left, including carry */ | |
46 | for (i = 0; i < bl - 1; i++, c = cnext) | |
47 | k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7); | |
48 | ||
49 | /* If MSB set fixup with R */ | |
50 | k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b)); | |
51 | } | |
52 | ||
53 | CMAC_CTX *CMAC_CTX_new(void) | |
54 | { | |
55 | CMAC_CTX *ctx; | |
56 | ||
57 | if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) | |
58 | return NULL; | |
59 | ctx->cctx = EVP_CIPHER_CTX_new(); | |
60 | if (ctx->cctx == NULL) { | |
61 | OPENSSL_free(ctx); | |
62 | return NULL; | |
63 | } | |
64 | ctx->nlast_block = -1; | |
65 | return ctx; | |
66 | } | |
67 | ||
68 | void CMAC_CTX_cleanup(CMAC_CTX *ctx) | |
69 | { | |
70 | EVP_CIPHER_CTX_reset(ctx->cctx); | |
71 | OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH); | |
72 | OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH); | |
73 | OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH); | |
74 | OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH); | |
75 | ctx->nlast_block = -1; | |
76 | } | |
77 | ||
78 | EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx) | |
79 | { | |
80 | return ctx->cctx; | |
81 | } | |
82 | ||
83 | void CMAC_CTX_free(CMAC_CTX *ctx) | |
84 | { | |
85 | if (!ctx) | |
86 | return; | |
87 | CMAC_CTX_cleanup(ctx); | |
88 | EVP_CIPHER_CTX_free(ctx->cctx); | |
89 | OPENSSL_free(ctx); | |
90 | } | |
91 | ||
92 | int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) | |
93 | { | |
94 | int bl; | |
95 | ||
96 | if (in->nlast_block == -1) | |
97 | return 0; | |
98 | if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) == 0) | |
99 | return 0; | |
100 | if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx)) | |
101 | return 0; | |
102 | memcpy(out->k1, in->k1, bl); | |
103 | memcpy(out->k2, in->k2, bl); | |
104 | memcpy(out->tbl, in->tbl, bl); | |
105 | memcpy(out->last_block, in->last_block, bl); | |
106 | out->nlast_block = in->nlast_block; | |
107 | return 1; | |
108 | } | |
109 | ||
110 | int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen, | |
111 | const EVP_CIPHER *cipher, ENGINE *impl) | |
112 | { | |
113 | static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 }; | |
114 | int block_len; | |
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 | block_len = EVP_CIPHER_CTX_get_block_size(ctx->cctx); | |
124 | if (block_len == 0) | |
125 | return 0; | |
126 | memset(ctx->tbl, 0, block_len); | |
127 | ctx->nlast_block = 0; | |
128 | return 1; | |
129 | } | |
130 | /* Initialise context */ | |
131 | if (cipher != NULL) { | |
132 | /* Ensure we can't use this ctx until we also have a key */ | |
133 | ctx->nlast_block = -1; | |
134 | if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL)) | |
135 | return 0; | |
136 | } | |
137 | /* Non-NULL key means initialisation complete */ | |
138 | if (key != NULL) { | |
139 | int bl; | |
140 | ||
141 | /* If anything fails then ensure we can't use this ctx */ | |
142 | ctx->nlast_block = -1; | |
143 | if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL) | |
144 | return 0; | |
145 | if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0) | |
146 | return 0; | |
147 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv)) | |
148 | return 0; | |
149 | if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0) | |
150 | return 0; | |
151 | if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0) | |
152 | return 0; | |
153 | make_kn(ctx->k1, ctx->tbl, bl); | |
154 | make_kn(ctx->k2, ctx->k1, bl); | |
155 | OPENSSL_cleanse(ctx->tbl, bl); | |
156 | /* Reset context again ready for first data block */ | |
157 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv)) | |
158 | return 0; | |
159 | /* Zero tbl so resume works */ | |
160 | memset(ctx->tbl, 0, bl); | |
161 | ctx->nlast_block = 0; | |
162 | } | |
163 | return 1; | |
164 | } | |
165 | ||
166 | int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen) | |
167 | { | |
168 | const unsigned char *data = in; | |
169 | int bl; | |
170 | size_t max_burst_blocks, cipher_blocks; | |
171 | unsigned char buf[LOCAL_BUF_SIZE]; | |
172 | ||
173 | if (ctx->nlast_block == -1) | |
174 | return 0; | |
175 | if (dlen == 0) | |
176 | return 1; | |
177 | if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0) | |
178 | return 0; | |
179 | /* Copy into partial block if we need to */ | |
180 | if (ctx->nlast_block > 0) { | |
181 | size_t nleft; | |
182 | ||
183 | nleft = bl - ctx->nlast_block; | |
184 | if (dlen < nleft) | |
185 | nleft = dlen; | |
186 | memcpy(ctx->last_block + ctx->nlast_block, data, nleft); | |
187 | dlen -= nleft; | |
188 | ctx->nlast_block += nleft; | |
189 | /* If no more to process return */ | |
190 | if (dlen == 0) | |
191 | return 1; | |
192 | data += nleft; | |
193 | /* Else not final block so encrypt it */ | |
194 | if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0) | |
195 | return 0; | |
196 | } | |
197 | /* Encrypt all but one of the complete blocks left */ | |
198 | ||
199 | max_burst_blocks = LOCAL_BUF_SIZE / bl; | |
200 | cipher_blocks = (dlen - 1) / bl; | |
201 | if (max_burst_blocks == 0) { | |
202 | /* | |
203 | * When block length is greater than local buffer size, | |
204 | * use ctx->tbl as cipher output. | |
205 | */ | |
206 | while (dlen > (size_t)bl) { | |
207 | if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0) | |
208 | return 0; | |
209 | dlen -= bl; | |
210 | data += bl; | |
211 | } | |
212 | } else { | |
213 | while (cipher_blocks > max_burst_blocks) { | |
214 | if (EVP_Cipher(ctx->cctx, buf, data, max_burst_blocks * bl) <= 0) | |
215 | return 0; | |
216 | dlen -= max_burst_blocks * bl; | |
217 | data += max_burst_blocks * bl; | |
218 | cipher_blocks -= max_burst_blocks; | |
219 | } | |
220 | if (cipher_blocks > 0) { | |
221 | if (EVP_Cipher(ctx->cctx, buf, data, cipher_blocks * bl) <= 0) | |
222 | return 0; | |
223 | dlen -= cipher_blocks * bl; | |
224 | data += cipher_blocks * bl; | |
225 | memcpy(ctx->tbl, &buf[(cipher_blocks - 1) * bl], bl); | |
226 | } | |
227 | } | |
228 | /* Copy any data left to last block buffer */ | |
229 | memcpy(ctx->last_block, data, dlen); | |
230 | ctx->nlast_block = dlen; | |
231 | return 1; | |
232 | ||
233 | } | |
234 | ||
235 | int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen) | |
236 | { | |
237 | int i, bl, lb; | |
238 | ||
239 | if (ctx->nlast_block == -1) | |
240 | return 0; | |
241 | if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0) | |
242 | return 0; | |
243 | if (poutlen != NULL) | |
244 | *poutlen = (size_t)bl; | |
245 | if (!out) | |
246 | return 1; | |
247 | lb = ctx->nlast_block; | |
248 | /* Is last block complete? */ | |
249 | if (lb == bl) { | |
250 | for (i = 0; i < bl; i++) | |
251 | out[i] = ctx->last_block[i] ^ ctx->k1[i]; | |
252 | } else { | |
253 | ctx->last_block[lb] = 0x80; | |
254 | if (bl - lb > 1) | |
255 | memset(ctx->last_block + lb + 1, 0, bl - lb - 1); | |
256 | for (i = 0; i < bl; i++) | |
257 | out[i] = ctx->last_block[i] ^ ctx->k2[i]; | |
258 | } | |
259 | if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) { | |
260 | OPENSSL_cleanse(out, bl); | |
261 | return 0; | |
262 | } | |
263 | return 1; | |
264 | } | |
265 | ||
266 | int CMAC_resume(CMAC_CTX *ctx) | |
267 | { | |
268 | if (ctx->nlast_block == -1) | |
269 | return 0; | |
270 | /* | |
271 | * The buffer "tbl" contains the last fully encrypted block which is the | |
272 | * last IV (or all zeroes if no last encrypted block). The last block has | |
273 | * not been modified since CMAC_final(). So reinitialising using the last | |
274 | * decrypted block will allow CMAC to continue after calling | |
275 | * CMAC_Final(). | |
276 | */ | |
277 | return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl); | |
278 | } |