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567db2c1 RL |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
7cfa1717 | 5 | EVP_MAC, EVP_MAC_fetch, EVP_MAC_up_ref, EVP_MAC_free, |
506cb0f6 | 6 | EVP_MAC_is_a, EVP_MAC_number, EVP_MAC_names_do_all, |
7dd0f299 | 7 | EVP_MAC_provider, EVP_MAC_get_params, EVP_MAC_gettable_params, |
e74bd290 RL |
8 | EVP_MAC_CTX, EVP_MAC_CTX_new, EVP_MAC_CTX_free, EVP_MAC_CTX_dup, |
9 | EVP_MAC_CTX_mac, EVP_MAC_CTX_get_params, EVP_MAC_CTX_set_params, | |
10 | EVP_MAC_size, EVP_MAC_init, EVP_MAC_update, EVP_MAC_final, | |
41f7ecf3 | 11 | EVP_MAC_gettable_ctx_params, EVP_MAC_settable_ctx_params, |
251e610c | 12 | EVP_MAC_do_all_provided - EVP MAC routines |
567db2c1 RL |
13 | |
14 | =head1 SYNOPSIS | |
15 | ||
16 | #include <openssl/evp.h> | |
17 | ||
18 | typedef struct evp_mac_st EVP_MAC; | |
19 | typedef struct evp_mac_ctx_st EVP_MAC_CTX; | |
20 | ||
e74bd290 RL |
21 | EVP_MAC *EVP_MAC_fetch(OPENSSL_CTX *libctx, const char *algorithm, |
22 | const char *properties); | |
23 | int EVP_MAC_up_ref(EVP_MAC *mac); | |
24 | void EVP_MAC_free(EVP_MAC *mac); | |
7cfa1717 | 25 | int EVP_MAC_is_a(const EVP_MAC *mac, const char *name); |
506cb0f6 | 26 | int EVP_MAC_number(const EVP_MAC *mac); |
f651c727 RL |
27 | void EVP_MAC_names_do_all(const EVP_MAC *mac, |
28 | void (*fn)(const char *name, void *data), | |
29 | void *data); | |
7dd0f299 | 30 | const OSSL_PROVIDER *EVP_MAC_provider(const EVP_MAC *mac); |
e74bd290 RL |
31 | int EVP_MAC_get_params(EVP_MAC *mac, OSSL_PARAM params[]); |
32 | ||
33 | EVP_MAC_CTX *EVP_MAC_CTX_new(EVP_MAC *mac); | |
567db2c1 | 34 | void EVP_MAC_CTX_free(EVP_MAC_CTX *ctx); |
be5fc053 | 35 | EVP_MAC_CTX *EVP_MAC_CTX_dup(const EVP_MAC_CTX *src); |
e74bd290 RL |
36 | EVP_MAC *EVP_MAC_CTX_mac(EVP_MAC_CTX *ctx); |
37 | int EVP_MAC_CTX_get_params(EVP_MAC_CTX *ctx, OSSL_PARAM params[]); | |
38 | int EVP_MAC_CTX_set_params(EVP_MAC_CTX *ctx, const OSSL_PARAM params[]); | |
39 | ||
567db2c1 RL |
40 | size_t EVP_MAC_size(EVP_MAC_CTX *ctx); |
41 | int EVP_MAC_init(EVP_MAC_CTX *ctx); | |
42 | int EVP_MAC_update(EVP_MAC_CTX *ctx, const unsigned char *data, size_t datalen); | |
e74bd290 RL |
43 | int EVP_MAC_final(EVP_MAC_CTX *ctx, |
44 | unsigned char *out, size_t *outl, size_t outsize); | |
45 | ||
46 | const OSSL_PARAM *EVP_MAC_gettable_params(const EVP_MAC *mac); | |
41f7ecf3 P |
47 | const OSSL_PARAM *EVP_MAC_gettable_ctx_params(const EVP_MAC *mac); |
48 | const OSSL_PARAM *EVP_MAC_settable_ctx_params(const EVP_MAC *mac); | |
567db2c1 | 49 | |
251e610c RL |
50 | void EVP_MAC_do_all_provided(OPENSSL_CTX *libctx, |
51 | void (*fn)(EVP_MAC *mac, void *arg), | |
52 | void *arg); | |
d1cafb08 | 53 | |
567db2c1 RL |
54 | =head1 DESCRIPTION |
55 | ||
56 | These types and functions help the application to calculate MACs of | |
57 | different types and with different underlying algorithms if there are | |
58 | any. | |
59 | ||
60 | MACs are a bit complex insofar that some of them use other algorithms | |
61 | for actual computation. HMAC uses a digest, and CMAC uses a cipher. | |
62 | Therefore, there are sometimes two contexts to keep track of, one for | |
63 | the MAC algorithm itself and one for the underlying computation | |
64 | algorithm if there is one. | |
65 | ||
66 | To make things less ambiguous, this manual talks about a "context" or | |
67 | "MAC context", which is to denote the MAC level context, and about a | |
68 | "underlying context", or "computation context", which is to denote the | |
69 | context for the underlying computation algorithm if there is one. | |
70 | ||
71 | =head2 Types | |
72 | ||
73 | B<EVP_MAC> is a type that holds the implementation of a MAC. | |
74 | ||
75 | B<EVP_MAC_CTX> is a context type that holds internal MAC information | |
76 | as well as a reference to a computation context, for those MACs that | |
77 | rely on an underlying computation algorithm. | |
78 | ||
e74bd290 RL |
79 | =head2 Algorithm implementation fetching |
80 | ||
81 | EVP_MAC_fetch() fetches an implementation of a MAC I<algorithm>, given | |
82 | a library context I<libctx> and a set of I<properties>. | |
83 | See L<provider(7)/Fetching algorithms> for further information. | |
84 | ||
85 | The returned value must eventually be freed with | |
86 | L<EVP_MAC_free(3)>. | |
87 | ||
88 | EVP_MAC_up_ref() increments the reference count of an already fetched | |
89 | MAC. | |
90 | ||
91 | EVP_MAC_free() frees a fetched algorithm. | |
92 | NULL is a valid parameter, for which this function is a no-op. | |
93 | ||
567db2c1 RL |
94 | =head2 Context manipulation functions |
95 | ||
e74bd290 | 96 | EVP_MAC_CTX_new() creates a new context for the MAC type I<mac>. |
567db2c1 RL |
97 | The created context can then be used with most other functions |
98 | described here. | |
99 | ||
100 | EVP_MAC_CTX_free() frees the contents of the context, including an | |
101 | underlying context if there is one, as well as the context itself. | |
e74bd290 | 102 | NULL is a valid parameter, for which this function is a no-op. |
567db2c1 | 103 | |
e74bd290 | 104 | EVP_MAC_CTX_dup() duplicates the I<src> context and returns a newly allocated |
be5fc053 | 105 | context. |
567db2c1 RL |
106 | |
107 | EVP_MAC_CTX_mac() returns the B<EVP_MAC> associated with the context | |
e74bd290 | 108 | I<ctx>. |
567db2c1 RL |
109 | |
110 | =head2 Computing functions | |
111 | ||
112 | EVP_MAC_init() sets up the underlying context with information given | |
113 | through diverse controls. | |
114 | This should be called before calling EVP_MAC_update() and | |
115 | EVP_MAC_final(). | |
116 | ||
e74bd290 | 117 | EVP_MAC_update() adds I<datalen> bytes from I<data> to the MAC input. |
567db2c1 RL |
118 | |
119 | EVP_MAC_final() does the final computation and stores the result in | |
e74bd290 RL |
120 | the memory pointed at by I<out> of size I<outsize>, and sets the number |
121 | of bytes written in I<*outl> at. | |
ee2161e8 | 122 | If I<out> is NULL or I<outsize> is too small, then no computation |
e74bd290 | 123 | is made. |
567db2c1 | 124 | To figure out what the output length will be and allocate space for it |
ee2161e8 | 125 | dynamically, simply call with I<out> being NULL and I<outl> |
567db2c1 | 126 | pointing at a valid location, then allocate space and make a second |
e74bd290 RL |
127 | call with I<out> pointing at the allocated space. |
128 | ||
129 | EVP_MAC_get_params() retrieves details about the implementation | |
130 | I<mac>. | |
131 | The set of parameters given with I<params> determine exactly what | |
132 | parameters should be retrieved. | |
133 | Note that a parameter that is unknown in the underlying context is | |
134 | simply ignored. | |
135 | ||
136 | EVP_MAC_CTX_get_params() retrieves chosen parameters, given the | |
137 | context I<ctx> and its underlying context. | |
138 | The set of parameters given with I<params> determine exactly what | |
139 | parameters should be retrieved. | |
140 | Note that a parameter that is unknown in the underlying context is | |
141 | simply ignored. | |
142 | ||
143 | EVP_MAC_CTX_set_params() passes chosen parameters to the underlying | |
144 | context, given a context I<ctx>. | |
145 | The set of parameters given with I<params> determine exactly what | |
146 | parameters are passed down. | |
147 | Note that a parameter that is unknown in the underlying context is | |
148 | simply ignored. | |
149 | Also, what happens when a needed parameter isn't passed down is | |
150 | defined by the implementation. | |
151 | ||
41f7ecf3 P |
152 | EVP_MAC_gettable_params(), EVP_MAC_gettable_ctx_params() and |
153 | EVP_MAC_settable_ctx_params() get a constant B<OSSL_PARAM> array that | |
e74bd290 | 154 | decribes the retrievable and settable parameters, i.e. parameters that |
ba24076f | 155 | can be used with EVP_MAC_get_params(), EVP_MAC_CTX_get_params() |
e74bd290 RL |
156 | and EVP_MAC_CTX_set_params(), respectively. |
157 | See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor. | |
567db2c1 RL |
158 | |
159 | =head2 Information functions | |
160 | ||
161 | EVP_MAC_size() returns the MAC output size for the given context. | |
162 | ||
7cfa1717 RL |
163 | EVP_MAC_is_a() checks if the given I<mac> is an implementation of an |
164 | algorithm that's identifiable with I<name>. | |
165 | ||
7dd0f299 RL |
166 | EVP_MAC_provider() returns the provider that holds the implementation |
167 | of the given I<mac>. | |
168 | ||
251e610c | 169 | EVP_MAC_do_all_provided() traverses all MAC implemented by all activated |
d1cafb08 RL |
170 | providers in the given library context I<libctx>, and for each of the |
171 | implementations, calls the given function I<fn> with the implementation method | |
172 | and the given I<arg> as argument. | |
173 | ||
506cb0f6 RL |
174 | EVP_MAC_number() returns the internal dynamic number assigned to |
175 | I<mac>. | |
176 | ||
f651c727 RL |
177 | EVP_MAC_names_do_all() traverses all names for I<mac>, and calls |
178 | I<fn> with each name and I<data>. | |
179 | ||
b1cabee8 | 180 | =head1 PARAMETERS |
567db2c1 | 181 | |
e592dbde RL |
182 | Parameters are identified by name as strings, and have an expected |
183 | data type and maximum size. | |
184 | OpenSSL has a set of macros for parameter names it expects to see in | |
185 | its own MAC implementations. | |
186 | Here, we show all three, the OpenSSL macro for the parameter name, the | |
187 | name in string form, and a type description. | |
188 | ||
e74bd290 | 189 | The standard parameter names are: |
567db2c1 RL |
190 | |
191 | =over 4 | |
192 | ||
0c452a51 | 193 | =item "key" (B<OSSL_MAC_PARAM_KEY>) <octet string> |
567db2c1 | 194 | |
e74bd290 | 195 | Its value is the MAC key as an array of bytes. |
567db2c1 RL |
196 | |
197 | For MACs that use an underlying computation algorithm, the algorithm | |
e74bd290 | 198 | must be set first, see parameter names "algorithm" below. |
afc580b9 | 199 | |
0c452a51 | 200 | =item "iv" (B<OSSL_MAC_PARAM_IV>) <octet string> |
afc580b9 | 201 | |
e74bd290 | 202 | Some MAC implementations require an IV, this parameter sets the IV. |
6e624a64 | 203 | |
0c452a51 | 204 | =item "custom" (B<OSSL_MAC_PARAM_CUSTOM>) <octet string> |
6e624a64 | 205 | |
13b3cd7b | 206 | Some MAC implementations (KMAC, BLAKE2) accept a Customization String, |
e74bd290 RL |
207 | this parameter sets the Customization String. The default value is the |
208 | empty string. | |
6e624a64 | 209 | |
0c452a51 | 210 | =item "salt" (B<OSSL_MAC_PARAM_SALT>) <octet string> |
13b3cd7b AS |
211 | |
212 | This option is used by BLAKE2 MAC. | |
213 | ||
0c452a51 | 214 | =item "xof" (B<OSSL_MAC_PARAM_XOF>) <integer> |
6e624a64 | 215 | |
e74bd290 | 216 | It's a simple flag, the value 0 or 1 are expected. |
6e624a64 SL |
217 | |
218 | This option is used by KMAC. | |
219 | ||
0c452a51 | 220 | =item "flags" (B<OSSL_MAC_PARAM_FLAGS>) <integer> |
567db2c1 RL |
221 | |
222 | These will set the MAC flags to the given numbers. | |
223 | Some MACs do not support this option. | |
224 | ||
0c452a51 | 225 | =item "properties" (B<OSSL_MAC_PARAM_PROPERTIES>) <UTF8 string> |
567db2c1 | 226 | |
0c452a51 | 227 | =item "digest" (B<OSSL_MAC_PARAM_DIGEST>) <UTF8 string> |
567db2c1 | 228 | |
0c452a51 | 229 | =item "cipher" (B<OSSL_MAC_PARAM_CIPHER>) <UTF8 string> |
e74bd290 | 230 | |
f3b8d77f | 231 | For MAC implementations that use an underlying computation cipher or |
9bd9c440 | 232 | digest, these parameters set what the algorithm should be. |
567db2c1 | 233 | |
9bd9c440 | 234 | The value is always the name of the intended algorithm, |
f3b8d77f | 235 | or the properties. |
567db2c1 | 236 | |
e74bd290 RL |
237 | Note that not all algorithms may support all digests. |
238 | HMAC does not support variable output length digests such as SHAKE128 | |
239 | or SHAKE256. | |
567db2c1 | 240 | |
0c452a51 | 241 | =item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer> |
567db2c1 RL |
242 | |
243 | For MAC implementations that support it, set the output size that | |
244 | EVP_MAC_final() should produce. | |
1aa01009 P |
245 | The allowed sizes vary between MAC implementations, but must never exceed |
246 | what can be given with a B<size_t>. | |
567db2c1 RL |
247 | |
248 | =back | |
249 | ||
e74bd290 | 250 | All these parameters should be used before the calls to any of |
567db2c1 RL |
251 | EVP_MAC_init(), EVP_MAC_update() and EVP_MAC_final() for a full |
252 | computation. | |
253 | Anything else may give undefined results. | |
254 | ||
e74bd290 | 255 | =head1 RETURN VALUES |
567db2c1 | 256 | |
e74bd290 RL |
257 | EVP_MAC_fetch() returns a pointer to a newly fetched EVP_MAC, or |
258 | NULL if allocation failed. | |
567db2c1 | 259 | |
e74bd290 RL |
260 | EVP_MAC_up_ref() returns 1 on success, 0 on error. |
261 | ||
262 | EVP_MAC_free() returns nothing at all. | |
263 | ||
7cfa1717 RL |
264 | EVP_MAC_is_a() returns 1 if the given method can be identified with |
265 | the given name, otherwise 0. | |
266 | ||
7dd0f299 RL |
267 | EVP_MAC_provider() returns a pointer to the provider for the MAC, or |
268 | NULL on error. | |
269 | ||
e74bd290 RL |
270 | EVP_MAC_CTX_new() and EVP_MAC_CTX_dup() return a pointer to a newly |
271 | created EVP_MAC_CTX, or NULL if allocation failed. | |
567db2c1 RL |
272 | |
273 | EVP_MAC_CTX_free() returns nothing at all. | |
274 | ||
e74bd290 RL |
275 | EVP_MAC_CTX_get_params() and EVP_MAC_CTX_set_params() return 1 on |
276 | success, 0 on error. | |
567db2c1 | 277 | |
e74bd290 RL |
278 | EVP_MAC_init(), EVP_MAC_update(), and EVP_MAC_final() return 1 on success, 0 |
279 | on error. | |
567db2c1 RL |
280 | |
281 | EVP_MAC_size() returns the expected output size, or 0 if it isn't | |
282 | set. | |
283 | If it isn't set, a call to EVP_MAC_init() should get it set. | |
284 | ||
251e610c | 285 | EVP_MAC_do_all_provided() returns nothing at all. |
567db2c1 | 286 | |
cda77422 | 287 | =head1 EXAMPLES |
567db2c1 RL |
288 | |
289 | #include <stdlib.h> | |
290 | #include <stdio.h> | |
291 | #include <string.h> | |
292 | #include <stdarg.h> | |
293 | #include <unistd.h> | |
294 | ||
295 | #include <openssl/evp.h> | |
296 | #include <openssl/err.h> | |
e74bd290 | 297 | #include <openssl/params.h> |
567db2c1 RL |
298 | |
299 | int main() { | |
e74bd290 RL |
300 | EVP_MAC *mac = EVP_MAC_fetch(NULL, getenv("MY_MAC"), NULL); |
301 | const char *cipher = getenv("MY_MAC_CIPHER"); | |
302 | const char *digest = getenv("MY_MAC_DIGEST"); | |
567db2c1 RL |
303 | const char *key = getenv("MY_KEY"); |
304 | EVP_MAC_CTX *ctx = NULL; | |
305 | ||
306 | unsigned char buf[4096]; | |
307 | ssize_t read_l; | |
308 | size_t final_l; | |
309 | ||
310 | size_t i; | |
311 | ||
e74bd290 RL |
312 | OSSL_PARAM params[4]; |
313 | size_t params_n = 0; | |
314 | ||
315 | if (cipher != NULL) | |
316 | params[params_n++] = | |
7f588d20 | 317 | OSSL_PARAM_construct_utf8_string("cipher", cipher, 0, NULL); |
e74bd290 RL |
318 | if (digest != NULL) |
319 | params[params_n++] = | |
7f588d20 | 320 | OSSL_PARAM_construct_utf8_string("digest", digest, 0, NULL); |
e74bd290 RL |
321 | params[params_n++] = |
322 | OSSL_PARAM_construct_octet_string("key", key, strlen(key), NULL); | |
323 | params[params_n] = OSSL_PARAM_construct_end(); | |
324 | ||
567db2c1 RL |
325 | if (mac == NULL |
326 | || key == NULL | |
327 | || (ctx = EVP_MAC_CTX_new(mac)) == NULL | |
e74bd290 | 328 | || EVP_MAC_CTX_set_params(ctx, params) <= 0) |
567db2c1 RL |
329 | goto err; |
330 | ||
331 | if (!EVP_MAC_init(ctx)) | |
332 | goto err; | |
333 | ||
334 | while ( (read_l = read(STDIN_FILENO, buf, sizeof(buf))) < 0) { | |
335 | if (!EVP_MAC_update(ctx, buf, read_l)) | |
336 | goto err; | |
337 | } | |
338 | ||
339 | if (!EVP_MAC_final(ctx, buf, &final_l)) | |
340 | goto err; | |
341 | ||
342 | printf("Result: "); | |
343 | for (i = 0; i < final_l; i++) | |
344 | printf("%02X", buf[i]); | |
345 | printf("\n"); | |
346 | ||
347 | EVP_MAC_CTX_free(ctx); | |
e74bd290 | 348 | EVP_MAC_free(mac); |
567db2c1 RL |
349 | exit(0); |
350 | ||
351 | err: | |
352 | EVP_MAC_CTX_free(ctx); | |
e74bd290 | 353 | EVP_MAC_free(mac); |
567db2c1 RL |
354 | fprintf(stderr, "Something went wrong\n"); |
355 | ERR_print_errors_fp(stderr); | |
356 | exit (1); | |
357 | } | |
358 | ||
359 | A run of this program, called with correct environment variables, can | |
360 | look like this: | |
361 | ||
362 | $ MY_MAC=cmac MY_KEY=secret0123456789 MY_MAC_CIPHER=aes-128-cbc \ | |
363 | LD_LIBRARY_PATH=. ./foo < foo.c | |
364 | Result: ECCAAFF041B22A2299EB90A1B53B6D45 | |
365 | ||
366 | (in this example, that program was stored in F<foo.c> and compiled to | |
367 | F<./foo>) | |
368 | ||
369 | =head1 SEE ALSO | |
370 | ||
e74bd290 RL |
371 | L<property(7)> |
372 | L<OSSL_PARAM(3)>, | |
d7cea0b8 RS |
373 | L<EVP_MAC-BLAKE2(7)>, |
374 | L<EVP_MAC-CMAC(7)>, | |
375 | L<EVP_MAC-GMAC(7)>, | |
376 | L<EVP_MAC-HMAC(7)>, | |
377 | L<EVP_MAC-KMAC(7)>, | |
378 | L<EVP_MAC-Siphash(7)>, | |
379 | L<EVP_MAC-Poly1305(7)> | |
567db2c1 | 380 | |
be5fc053 KR |
381 | =head1 HISTORY |
382 | ||
4674aaf4 | 383 | These functions were added in OpenSSL 3.0. |
be5fc053 | 384 | |
567db2c1 RL |
385 | =head1 COPYRIGHT |
386 | ||
e74bd290 | 387 | Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved. |
567db2c1 | 388 | |
4746f25a | 389 | Licensed under the Apache License 2.0 (the "License"). You may not use |
567db2c1 RL |
390 | this file except in compliance with the License. You can obtain a copy |
391 | in the file LICENSE in the source distribution or at | |
392 | L<https://www.openssl.org/source/license.html>. | |
393 | ||
394 | =cut |