]>
Commit | Line | Data |
---|---|---|
567db2c1 RL |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
7cfa1717 RL |
5 | EVP_MAC, EVP_MAC_fetch, EVP_MAC_up_ref, EVP_MAC_free, |
6 | EVP_MAC_is_a, EVP_MAC_name, | |
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, | |
d1cafb08 RL |
11 | EVP_MAC_CTX_gettable_params, EVP_MAC_CTX_settable_params, |
12 | EVP_MAC_do_all_ex - 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); |
e74bd290 | 26 | const char *EVP_MAC_name(const EVP_MAC *mac); |
7dd0f299 | 27 | const OSSL_PROVIDER *EVP_MAC_provider(const EVP_MAC *mac); |
e74bd290 RL |
28 | int EVP_MAC_get_params(EVP_MAC *mac, OSSL_PARAM params[]); |
29 | ||
30 | EVP_MAC_CTX *EVP_MAC_CTX_new(EVP_MAC *mac); | |
567db2c1 | 31 | void EVP_MAC_CTX_free(EVP_MAC_CTX *ctx); |
be5fc053 | 32 | EVP_MAC_CTX *EVP_MAC_CTX_dup(const EVP_MAC_CTX *src); |
e74bd290 RL |
33 | EVP_MAC *EVP_MAC_CTX_mac(EVP_MAC_CTX *ctx); |
34 | int EVP_MAC_CTX_get_params(EVP_MAC_CTX *ctx, OSSL_PARAM params[]); | |
35 | int EVP_MAC_CTX_set_params(EVP_MAC_CTX *ctx, const OSSL_PARAM params[]); | |
36 | ||
567db2c1 RL |
37 | size_t EVP_MAC_size(EVP_MAC_CTX *ctx); |
38 | int EVP_MAC_init(EVP_MAC_CTX *ctx); | |
39 | int EVP_MAC_update(EVP_MAC_CTX *ctx, const unsigned char *data, size_t datalen); | |
e74bd290 RL |
40 | int EVP_MAC_final(EVP_MAC_CTX *ctx, |
41 | unsigned char *out, size_t *outl, size_t outsize); | |
42 | ||
43 | const OSSL_PARAM *EVP_MAC_gettable_params(const EVP_MAC *mac); | |
44 | const OSSL_PARAM *EVP_MAC_CTX_gettable_params(const EVP_MAC *mac); | |
45 | const OSSL_PARAM *EVP_MAC_CTX_settable_params(const EVP_MAC *mac); | |
567db2c1 | 46 | |
d1cafb08 RL |
47 | void EVP_MAC_do_all_ex(OPENSSL_CTX *libctx, |
48 | void (*fn)(EVP_MAC *mac, void *arg), | |
49 | void *arg); | |
50 | ||
567db2c1 RL |
51 | =head1 DESCRIPTION |
52 | ||
53 | These types and functions help the application to calculate MACs of | |
54 | different types and with different underlying algorithms if there are | |
55 | any. | |
56 | ||
57 | MACs are a bit complex insofar that some of them use other algorithms | |
58 | for actual computation. HMAC uses a digest, and CMAC uses a cipher. | |
59 | Therefore, there are sometimes two contexts to keep track of, one for | |
60 | the MAC algorithm itself and one for the underlying computation | |
61 | algorithm if there is one. | |
62 | ||
63 | To make things less ambiguous, this manual talks about a "context" or | |
64 | "MAC context", which is to denote the MAC level context, and about a | |
65 | "underlying context", or "computation context", which is to denote the | |
66 | context for the underlying computation algorithm if there is one. | |
67 | ||
68 | =head2 Types | |
69 | ||
70 | B<EVP_MAC> is a type that holds the implementation of a MAC. | |
71 | ||
72 | B<EVP_MAC_CTX> is a context type that holds internal MAC information | |
73 | as well as a reference to a computation context, for those MACs that | |
74 | rely on an underlying computation algorithm. | |
75 | ||
e74bd290 RL |
76 | =head2 Algorithm implementation fetching |
77 | ||
78 | EVP_MAC_fetch() fetches an implementation of a MAC I<algorithm>, given | |
79 | a library context I<libctx> and a set of I<properties>. | |
80 | See L<provider(7)/Fetching algorithms> for further information. | |
81 | ||
82 | The returned value must eventually be freed with | |
83 | L<EVP_MAC_free(3)>. | |
84 | ||
85 | EVP_MAC_up_ref() increments the reference count of an already fetched | |
86 | MAC. | |
87 | ||
88 | EVP_MAC_free() frees a fetched algorithm. | |
89 | NULL is a valid parameter, for which this function is a no-op. | |
90 | ||
567db2c1 RL |
91 | =head2 Context manipulation functions |
92 | ||
e74bd290 | 93 | EVP_MAC_CTX_new() creates a new context for the MAC type I<mac>. |
567db2c1 RL |
94 | The created context can then be used with most other functions |
95 | described here. | |
96 | ||
97 | EVP_MAC_CTX_free() frees the contents of the context, including an | |
98 | underlying context if there is one, as well as the context itself. | |
e74bd290 | 99 | NULL is a valid parameter, for which this function is a no-op. |
567db2c1 | 100 | |
e74bd290 | 101 | EVP_MAC_CTX_dup() duplicates the I<src> context and returns a newly allocated |
be5fc053 | 102 | context. |
567db2c1 RL |
103 | |
104 | EVP_MAC_CTX_mac() returns the B<EVP_MAC> associated with the context | |
e74bd290 | 105 | I<ctx>. |
567db2c1 RL |
106 | |
107 | =head2 Computing functions | |
108 | ||
109 | EVP_MAC_init() sets up the underlying context with information given | |
110 | through diverse controls. | |
111 | This should be called before calling EVP_MAC_update() and | |
112 | EVP_MAC_final(). | |
113 | ||
e74bd290 | 114 | EVP_MAC_update() adds I<datalen> bytes from I<data> to the MAC input. |
567db2c1 RL |
115 | |
116 | EVP_MAC_final() does the final computation and stores the result in | |
e74bd290 RL |
117 | the memory pointed at by I<out> of size I<outsize>, and sets the number |
118 | of bytes written in I<*outl> at. | |
119 | If I<out> is B<NULL> or I<outsize> is too small, then no computation | |
120 | is made. | |
567db2c1 | 121 | To figure out what the output length will be and allocate space for it |
e74bd290 | 122 | dynamically, simply call with I<out> being B<NULL> and I<outl> |
567db2c1 | 123 | pointing at a valid location, then allocate space and make a second |
e74bd290 RL |
124 | call with I<out> pointing at the allocated space. |
125 | ||
126 | EVP_MAC_get_params() retrieves details about the implementation | |
127 | I<mac>. | |
128 | The set of parameters given with I<params> determine exactly what | |
129 | parameters should be retrieved. | |
130 | Note that a parameter that is unknown in the underlying context is | |
131 | simply ignored. | |
132 | ||
133 | EVP_MAC_CTX_get_params() retrieves chosen parameters, given the | |
134 | context I<ctx> and its underlying context. | |
135 | The set of parameters given with I<params> determine exactly what | |
136 | parameters should be retrieved. | |
137 | Note that a parameter that is unknown in the underlying context is | |
138 | simply ignored. | |
139 | ||
140 | EVP_MAC_CTX_set_params() passes chosen parameters to the underlying | |
141 | context, given a context I<ctx>. | |
142 | The set of parameters given with I<params> determine exactly what | |
143 | parameters are passed down. | |
144 | Note that a parameter that is unknown in the underlying context is | |
145 | simply ignored. | |
146 | Also, what happens when a needed parameter isn't passed down is | |
147 | defined by the implementation. | |
148 | ||
149 | EVP_MAC_gettable_params(), EVP_MAC_CTX_gettable_params() and | |
150 | EVP_MAC_CTX_settable_params() get a constant B<OSSL_PARAM> array that | |
151 | decribes the retrievable and settable parameters, i.e. parameters that | |
ba24076f | 152 | can be used with EVP_MAC_get_params(), EVP_MAC_CTX_get_params() |
e74bd290 RL |
153 | and EVP_MAC_CTX_set_params(), respectively. |
154 | See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor. | |
567db2c1 RL |
155 | |
156 | =head2 Information functions | |
157 | ||
158 | EVP_MAC_size() returns the MAC output size for the given context. | |
159 | ||
567db2c1 RL |
160 | EVP_MAC_name() returns the name of the given MAC implementation. |
161 | ||
7cfa1717 RL |
162 | EVP_MAC_is_a() checks if the given I<mac> is an implementation of an |
163 | algorithm that's identifiable with I<name>. | |
164 | ||
7dd0f299 RL |
165 | EVP_MAC_provider() returns the provider that holds the implementation |
166 | of the given I<mac>. | |
167 | ||
d1cafb08 RL |
168 | EVP_MAC_do_all_ex() traverses all MAC implemented by all activated |
169 | providers in the given library context I<libctx>, and for each of the | |
170 | implementations, calls the given function I<fn> with the implementation method | |
171 | and the given I<arg> as argument. | |
172 | ||
b1cabee8 | 173 | =head1 PARAMETERS |
567db2c1 | 174 | |
e592dbde RL |
175 | Parameters are identified by name as strings, and have an expected |
176 | data type and maximum size. | |
177 | OpenSSL has a set of macros for parameter names it expects to see in | |
178 | its own MAC implementations. | |
179 | Here, we show all three, the OpenSSL macro for the parameter name, the | |
180 | name in string form, and a type description. | |
181 | ||
e74bd290 | 182 | The standard parameter names are: |
567db2c1 RL |
183 | |
184 | =over 4 | |
185 | ||
e592dbde | 186 | =item B<OSSL_MAC_PARAM_KEY> ("key") <octet string> |
567db2c1 | 187 | |
e74bd290 | 188 | Its value is the MAC key as an array of bytes. |
567db2c1 RL |
189 | |
190 | For MACs that use an underlying computation algorithm, the algorithm | |
e74bd290 | 191 | must be set first, see parameter names "algorithm" below. |
afc580b9 | 192 | |
e592dbde | 193 | =item B<OSSL_MAC_PARAM_IV> ("iv") <octet string> |
afc580b9 | 194 | |
e74bd290 | 195 | Some MAC implementations require an IV, this parameter sets the IV. |
6e624a64 | 196 | |
e592dbde | 197 | =item B<OSSL_MAC_PARAM_CUSTOM> ("custom") <octet string> |
6e624a64 | 198 | |
13b3cd7b | 199 | Some MAC implementations (KMAC, BLAKE2) accept a Customization String, |
e74bd290 RL |
200 | this parameter sets the Customization String. The default value is the |
201 | empty string. | |
6e624a64 | 202 | |
e592dbde | 203 | =item B<OSSL_MAC_PARAM_SALT> ("salt") <octet string> |
13b3cd7b AS |
204 | |
205 | This option is used by BLAKE2 MAC. | |
206 | ||
e9147bd4 | 207 | =item B<OSSL_MAC_PARAM_XOF> ("xof") <integer> |
6e624a64 | 208 | |
e74bd290 | 209 | It's a simple flag, the value 0 or 1 are expected. |
6e624a64 SL |
210 | |
211 | This option is used by KMAC. | |
212 | ||
e9147bd4 | 213 | =item B<OSSL_MAC_PARAM_FLAGS> ("flags") <integer> |
567db2c1 RL |
214 | |
215 | These will set the MAC flags to the given numbers. | |
216 | Some MACs do not support this option. | |
217 | ||
1aa01009 | 218 | =item B<OSSL_MAC_PARAM_ENGINE> ("engine") <UTF8 string> |
e74bd290 | 219 | |
1aa01009 | 220 | =item B<OSSL_MAC_PARAM_PROPERTIES> ("properties") <UTF8 string> |
567db2c1 | 221 | |
1aa01009 | 222 | =item B<OSSL_MAC_PARAM_DIGEST> ("digest") <UTF8 string> |
567db2c1 | 223 | |
1aa01009 | 224 | =item B<OSSL_MAC_PARAM_CIPHER> ("cipher") <UTF8 string> |
e74bd290 | 225 | |
f3b8d77f RL |
226 | For MAC implementations that use an underlying computation cipher or |
227 | digest, these parameters set what the algorithm should be, and the | |
228 | engine that implements the algorithm or the properties to fetch it | |
229 | by if needed. | |
567db2c1 | 230 | |
f3b8d77f RL |
231 | The value is always the name of the intended engine, algorithm, |
232 | or the properties. | |
567db2c1 | 233 | |
e74bd290 RL |
234 | Note that not all algorithms may support all digests. |
235 | HMAC does not support variable output length digests such as SHAKE128 | |
236 | or SHAKE256. | |
567db2c1 | 237 | |
e9147bd4 | 238 | =item B<OSSL_MAC_PARAM_SIZE> ("size") <unsigned integer> |
567db2c1 RL |
239 | |
240 | For MAC implementations that support it, set the output size that | |
241 | EVP_MAC_final() should produce. | |
1aa01009 P |
242 | The allowed sizes vary between MAC implementations, but must never exceed |
243 | what can be given with a B<size_t>. | |
567db2c1 RL |
244 | |
245 | =back | |
246 | ||
e74bd290 | 247 | All these parameters should be used before the calls to any of |
567db2c1 RL |
248 | EVP_MAC_init(), EVP_MAC_update() and EVP_MAC_final() for a full |
249 | computation. | |
250 | Anything else may give undefined results. | |
251 | ||
e74bd290 | 252 | =head1 RETURN VALUES |
567db2c1 | 253 | |
e74bd290 RL |
254 | EVP_MAC_fetch() returns a pointer to a newly fetched EVP_MAC, or |
255 | NULL if allocation failed. | |
567db2c1 | 256 | |
e74bd290 RL |
257 | EVP_MAC_up_ref() returns 1 on success, 0 on error. |
258 | ||
259 | EVP_MAC_free() returns nothing at all. | |
260 | ||
261 | EVP_MAC_name() returns the name of the MAC, or NULL if NULL was | |
262 | passed. | |
567db2c1 | 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 | ||
d1cafb08 | 285 | EVP_MAC_do_all_ex() 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)>, | |
13b3cd7b | 373 | L<EVP_MAC_BLAKE2(7)>, |
6723f867 | 374 | L<EVP_MAC_CMAC(7)>, |
afc580b9 | 375 | L<EVP_MAC_GMAC(7)>, |
c89d9cda | 376 | L<EVP_MAC_HMAC(7)>, |
6e624a64 | 377 | L<EVP_MAC_KMAC(7)>, |
c1da4b2a PY |
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 |