1 | /* |
2 | * Copyright 2010-2018 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 <stdio.h> |
11 | #include <stdlib.h> |
12 | #include <string.h> |
13 | #include "internal/cryptlib.h" |
14 | #include <openssl/cmac.h> |
15 | #include <openssl/err.h> |
16 | |
17 | struct CMAC_CTX_st { |
18 | /* Cipher context to use */ |
19 | EVP_CIPHER_CTX *cctx; |
20 | /* Keys k1 and k2 */ |
21 | unsigned char k1[EVP_MAX_BLOCK_LENGTH]; |
22 | unsigned char k2[EVP_MAX_BLOCK_LENGTH]; |
23 | /* Temporary block */ |
24 | unsigned char tbl[EVP_MAX_BLOCK_LENGTH]; |
25 | /* Last (possibly partial) block */ |
26 | unsigned char last_block[EVP_MAX_BLOCK_LENGTH]; |
27 | /* Number of bytes in last block: -1 means context not initialised */ |
28 | int nlast_block; |
29 | }; |
30 | |
31 | /* Make temporary keys K1 and K2 */ |
32 | |
33 | static void make_kn(unsigned char *k1, const unsigned char *l, int bl) |
34 | { |
35 | int i; |
36 | unsigned char c = l[0], carry = c >> 7, cnext; |
37 | |
38 | /* Shift block to left, including carry */ |
39 | for (i = 0; i < bl - 1; i++, c = cnext) |
40 | k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7); |
41 | |
42 | /* If MSB set fixup with R */ |
43 | k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b)); |
44 | } |
45 | |
46 | CMAC_CTX *CMAC_CTX_new(void) |
47 | { |
48 | CMAC_CTX *ctx; |
49 | |
50 | if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) { |
51 | CRYPTOerr(CRYPTO_F_CMAC_CTX_NEW, ERR_R_MALLOC_FAILURE); |
52 | return NULL; |
53 | } |
54 | ctx->cctx = EVP_CIPHER_CTX_new(); |
55 | if (ctx->cctx == NULL) { |
56 | OPENSSL_free(ctx); |
57 | return NULL; |
58 | } |
59 | ctx->nlast_block = -1; |
60 | return ctx; |
61 | } |
62 | |
63 | void CMAC_CTX_cleanup(CMAC_CTX *ctx) |
64 | { |
65 | EVP_CIPHER_CTX_reset(ctx->cctx); |
66 | OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH); |
67 | OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH); |
68 | OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH); |
69 | OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH); |
70 | ctx->nlast_block = -1; |
71 | } |
72 | |
73 | EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx) |
74 | { |
75 | return ctx->cctx; |
76 | } |
77 | |
78 | void CMAC_CTX_free(CMAC_CTX *ctx) |
79 | { |
80 | if (!ctx) |
81 | return; |
82 | CMAC_CTX_cleanup(ctx); |
83 | EVP_CIPHER_CTX_free(ctx->cctx); |
84 | OPENSSL_free(ctx); |
85 | } |
86 | |
87 | int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) |
88 | { |
89 | int bl; |
90 | |
91 | if (in->nlast_block == -1) |
92 | return 0; |
93 | if ((bl = EVP_CIPHER_CTX_block_size(in->cctx)) < 0) |
94 | return 0; |
95 | if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx)) |
96 | return 0; |
97 | memcpy(out->k1, in->k1, bl); |
98 | memcpy(out->k2, in->k2, bl); |
99 | memcpy(out->tbl, in->tbl, bl); |
100 | memcpy(out->last_block, in->last_block, bl); |
101 | out->nlast_block = in->nlast_block; |
102 | return 1; |
103 | } |
104 | |
105 | int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen, |
106 | const EVP_CIPHER *cipher, ENGINE *impl) |
107 | { |
108 | static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 }; |
109 | |
110 | /* All zeros means restart */ |
111 | if (!key && !cipher && !impl && keylen == 0) { |
112 | /* Not initialised */ |
113 | if (ctx->nlast_block == -1) |
114 | return 0; |
115 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv)) |
116 | return 0; |
117 | memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx)); |
118 | ctx->nlast_block = 0; |
119 | return 1; |
120 | } |
121 | /* Initialise context */ |
122 | if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL)) |
123 | return 0; |
124 | /* Non-NULL key means initialisation complete */ |
125 | if (key) { |
126 | int bl; |
127 | |
128 | if (!EVP_CIPHER_CTX_cipher(ctx->cctx)) |
129 | return 0; |
130 | if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen)) |
131 | return 0; |
132 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv)) |
133 | return 0; |
134 | if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0) |
135 | return 0; |
136 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl)) |
137 | return 0; |
138 | make_kn(ctx->k1, ctx->tbl, bl); |
139 | make_kn(ctx->k2, ctx->k1, bl); |
140 | OPENSSL_cleanse(ctx->tbl, bl); |
141 | /* Reset context again ready for first data block */ |
142 | if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv)) |
143 | return 0; |
144 | /* Zero tbl so resume works */ |
145 | memset(ctx->tbl, 0, bl); |
146 | ctx->nlast_block = 0; |
147 | } |
148 | return 1; |
149 | } |
150 | |
151 | int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen) |
152 | { |
153 | const unsigned char *data = in; |
154 | int bl; |
155 | |
156 | if (ctx->nlast_block == -1) |
157 | return 0; |
158 | if (dlen == 0) |
159 | return 1; |
160 | if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0) |
161 | return 0; |
162 | /* Copy into partial block if we need to */ |
163 | if (ctx->nlast_block > 0) { |
164 | size_t nleft; |
165 | |
166 | nleft = bl - ctx->nlast_block; |
167 | if (dlen < nleft) |
168 | nleft = dlen; |
169 | memcpy(ctx->last_block + ctx->nlast_block, data, nleft); |
170 | dlen -= nleft; |
171 | ctx->nlast_block += nleft; |
172 | /* If no more to process return */ |
173 | if (dlen == 0) |
174 | return 1; |
175 | data += nleft; |
176 | /* Else not final block so encrypt it */ |
177 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl)) |
178 | return 0; |
179 | } |
180 | /* Encrypt all but one of the complete blocks left */ |
181 | while (dlen > (size_t)bl) { |
182 | if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl)) |
183 | return 0; |
184 | dlen -= bl; |
185 | data += bl; |
186 | } |
187 | /* Copy any data left to last block buffer */ |
188 | memcpy(ctx->last_block, data, dlen); |
189 | ctx->nlast_block = dlen; |
190 | return 1; |
191 | |
192 | } |
193 | |
194 | int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen) |
195 | { |
196 | int i, bl, lb; |
197 | |
198 | if (ctx->nlast_block == -1) |
199 | return 0; |
200 | if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0) |
201 | return 0; |
202 | if (poutlen != NULL) |
203 | *poutlen = (size_t)bl; |
204 | if (!out) |
205 | return 1; |
206 | lb = ctx->nlast_block; |
207 | /* Is last block complete? */ |
208 | if (lb == bl) { |
209 | for (i = 0; i < bl; i++) |
210 | out[i] = ctx->last_block[i] ^ ctx->k1[i]; |
211 | } else { |
212 | ctx->last_block[lb] = 0x80; |
213 | if (bl - lb > 1) |
214 | memset(ctx->last_block + lb + 1, 0, bl - lb - 1); |
215 | for (i = 0; i < bl; i++) |
216 | out[i] = ctx->last_block[i] ^ ctx->k2[i]; |
217 | } |
218 | if (!EVP_Cipher(ctx->cctx, out, out, bl)) { |
219 | OPENSSL_cleanse(out, bl); |
220 | return 0; |
221 | } |
222 | return 1; |
223 | } |
224 | |
225 | int CMAC_resume(CMAC_CTX *ctx) |
226 | { |
227 | if (ctx->nlast_block == -1) |
228 | return 0; |
229 | /* |
230 | * The buffer "tbl" contains the last fully encrypted block which is the |
231 | * last IV (or all zeroes if no last encrypted block). The last block has |
232 | * not been modified since CMAC_final(). So reinitialising using the last |
233 | * decrypted block will allow CMAC to continue after calling |
234 | * CMAC_Final(). |
235 | */ |
236 | return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl); |
237 | } |
238 | |