1EVP_MAC(3ossl) OpenSSL EVP_MAC(3ossl)
2
6 EVP_MAC, EVP_MAC_fetch, EVP_MAC_up_ref, EVP_MAC_free, EVP_MAC_is_a,
7 EVP_MAC_get0_name, EVP_MAC_names_do_all, EVP_MAC_get0_description,
8 EVP_MAC_get0_provider, EVP_MAC_get_params, EVP_MAC_gettable_params,
9 EVP_MAC_CTX, EVP_MAC_CTX_new, EVP_MAC_CTX_free, EVP_MAC_CTX_dup,
10 EVP_MAC_CTX_get0_mac, EVP_MAC_CTX_get_params, EVP_MAC_CTX_set_params,
11 EVP_MAC_CTX_get_mac_size, EVP_MAC_CTX_get_block_size, EVP_Q_mac,
12 EVP_MAC_init, EVP_MAC_update, EVP_MAC_final, EVP_MAC_finalXOF,
13 EVP_MAC_gettable_ctx_params, EVP_MAC_settable_ctx_params,
14 EVP_MAC_CTX_gettable_params, EVP_MAC_CTX_settable_params,
15 EVP_MAC_do_all_provided - EVP MAC routines
16
18 #include <openssl/evp.h>
19 typedef struct evp_mac_st EVP_MAC;
21 typedef struct evp_mac_ctx_st EVP_MAC_CTX;
22 EVP_MAC *EVP_MAC_fetch(OSSL_LIB_CTX *libctx, const char *algorithm,
24 const char *properties);
25 int EVP_MAC_up_ref(EVP_MAC *mac);
26 void EVP_MAC_free(EVP_MAC *mac);
27 int EVP_MAC_is_a(const EVP_MAC *mac, const char *name);
28 const char *EVP_MAC_get0_name(const EVP_MAC *mac);
29 int EVP_MAC_names_do_all(const EVP_MAC *mac,
30 void (*fn)(const char *name, void *data),
31 void *data);
32 const char *EVP_MAC_get0_description(const EVP_MAC *mac);
33 const OSSL_PROVIDER *EVP_MAC_get0_provider(const EVP_MAC *mac);
34 int EVP_MAC_get_params(EVP_MAC *mac, OSSL_PARAM params[]);
35 EVP_MAC_CTX *EVP_MAC_CTX_new(EVP_MAC *mac);
37 void EVP_MAC_CTX_free(EVP_MAC_CTX *ctx);
38 EVP_MAC_CTX *EVP_MAC_CTX_dup(const EVP_MAC_CTX *src);
39 EVP_MAC *EVP_MAC_CTX_get0_mac(EVP_MAC_CTX *ctx);
40 int EVP_MAC_CTX_get_params(EVP_MAC_CTX *ctx, OSSL_PARAM params[]);
41 int EVP_MAC_CTX_set_params(EVP_MAC_CTX *ctx, const OSSL_PARAM params[]);
42 size_t EVP_MAC_CTX_get_mac_size(EVP_MAC_CTX *ctx);
44 size_t EVP_MAC_CTX_get_block_size(EVP_MAC_CTX *ctx);
45 unsigned char *EVP_Q_mac(OSSL_LIB_CTX *libctx, const char *name, const char *propq,
46 const char *subalg, const OSSL_PARAM *params,
47 const void *key, size_t keylen,
48 const unsigned char *data, size_t datalen,
49 unsigned char *out, size_t outsize, size_t *outlen);
50 int EVP_MAC_init(EVP_MAC_CTX *ctx, const unsigned char *key, size_t keylen,
51 const OSSL_PARAM params[]);
52 int EVP_MAC_update(EVP_MAC_CTX *ctx, const unsigned char *data, size_t datalen);
53 int EVP_MAC_final(EVP_MAC_CTX *ctx,
54 unsigned char *out, size_t *outl, size_t outsize);
55 int EVP_MAC_finalXOF(EVP_MAC_CTX *ctx, unsigned char *out, size_t outsize);
56 const OSSL_PARAM *EVP_MAC_gettable_params(const EVP_MAC *mac);
58 const OSSL_PARAM *EVP_MAC_gettable_ctx_params(const EVP_MAC *mac);
59 const OSSL_PARAM *EVP_MAC_settable_ctx_params(const EVP_MAC *mac);
60 const OSSL_PARAM *EVP_MAC_CTX_gettable_params(EVP_MAC_CTX *ctx);
61 const OSSL_PARAM *EVP_MAC_CTX_settable_params(EVP_MAC_CTX *ctx);
62 void EVP_MAC_do_all_provided(OSSL_LIB_CTX *libctx,
64 void (*fn)(EVP_MAC *mac, void *arg),
65 void *arg);
66
68 These types and functions help the application to calculate MACs of
69 different types and with different underlying algorithms if there are
70 any.
71 MACs are a bit complex insofar that some of them use other algorithms
73 for actual computation. HMAC uses a digest, and CMAC uses a cipher.
74 Therefore, there are sometimes two contexts to keep track of, one for
75 the MAC algorithm itself and one for the underlying computation
76 algorithm if there is one.
77 To make things less ambiguous, this manual talks about a "context" or
79 "MAC context", which is to denote the MAC level context, and about a
80 "underlying context", or "computation context", which is to denote the
81 context for the underlying computation algorithm if there is one.
82 Types
84 EVP_MAC is a type that holds the implementation of a MAC.
85 EVP_MAC_CTX is a context type that holds internal MAC information as
87 well as a reference to a computation context, for those MACs that rely
88 on an underlying computation algorithm.
89 Algorithm implementation fetching
91 EVP_MAC_fetch() fetches an implementation of a MAC algorithm, given a
92 library context libctx and a set of properties. See "ALGORITHM
93 FETCHING" in crypto(7) for further information.
94 See "Message Authentication Code (MAC)" in OSSL_PROVIDER-default(7) for
96 the list of algorithms supported by the default provider.
97 The returned value must eventually be freed with EVP_MAC_free(3).
99 EVP_MAC_up_ref() increments the reference count of an already fetched
101 MAC.
102 EVP_MAC_free() frees a fetched algorithm. NULL is a valid parameter,
104 for which this function is a no-op.
105 Context manipulation functions
107 EVP_MAC_CTX_new() creates a new context for the MAC type mac. The
108 created context can then be used with most other functions described
109 here.
110 EVP_MAC_CTX_free() frees the contents of the context, including an
112 underlying context if there is one, as well as the context itself.
113 NULL is a valid parameter, for which this function is a no-op.
114 EVP_MAC_CTX_dup() duplicates the src context and returns a newly
116 allocated context.
117 EVP_MAC_CTX_get0_mac() returns the EVP_MAC associated with the context
119 ctx.
120 Computing functions
122 EVP_Q_mac() computes the message authentication code of data with
123 length datalen using the MAC algorithm name and the key key with length
124 keylen. The MAC algorithm is fetched using any given libctx and
125 property query string propq. It takes parameters subalg and further
126 params, both of which may be NULL if not needed. If out is not NULL,
127 it places the result in the memory pointed at by out, but only if
128 outsize is sufficient (otherwise no computation is made). If out is
129 NULL, it allocates and uses a buffer of suitable length, which will be
130 returned on success and must be freed by the caller. In either case,
131 also on error, it assigns the number of bytes written to *outlen unless
132 outlen is NULL.
133 EVP_MAC_init() sets up the underlying context ctx with information
135 given via the key and params arguments. The MAC key has a length of
136 keylen and the parameters in params are processed before setting the
137 key. If key is NULL, the key must be set via params either as part of
138 this call or separately using EVP_MAC_CTX_set_params(). Providing non-
139 NULL params to this function is equivalent to calling
140 EVP_MAC_CTX_set_params() with those params for the same ctx beforehand.
141 EVP_MAC_init() should be called before EVP_MAC_update() and
143 EVP_MAC_final().
144 EVP_MAC_update() adds datalen bytes from data to the MAC input.
146 EVP_MAC_final() does the final computation and stores the result in the
148 memory pointed at by out of size outsize, and sets the number of bytes
149 written in *outl at. If out is NULL or outsize is too small, then no
150 computation is made. To figure out what the output length will be and
151 allocate space for it dynamically, simply call with out being NULL and
152 outl pointing at a valid location, then allocate space and make a
153 second call with out pointing at the allocated space.
154 EVP_MAC_finalXOF() does the final computation for an XOF based MAC and
156 stores the result in the memory pointed at by out of size outsize.
157 EVP_MAC_get_params() retrieves details about the implementation mac.
159 The set of parameters given with params determine exactly what
160 parameters should be retrieved. Note that a parameter that is unknown
161 in the underlying context is simply ignored.
162 EVP_MAC_CTX_get_params() retrieves chosen parameters, given the context
164 ctx and its underlying context. The set of parameters given with
165 params determine exactly what parameters should be retrieved. Note
166 that a parameter that is unknown in the underlying context is simply
167 ignored.
168 EVP_MAC_CTX_set_params() passes chosen parameters to the underlying
170 context, given a context ctx. The set of parameters given with params
171 determine exactly what parameters are passed down. If params are NULL,
172 the unterlying context should do nothing and return 1. Note that a
173 parameter that is unknown in the underlying context is simply ignored.
174 Also, what happens when a needed parameter isn't passed down is defined
175 by the implementation.
176 EVP_MAC_gettable_params() returns an OSSL_PARAM array that describes
178 the retrievable and settable parameters. EVP_MAC_gettable_params()
179 returns parameters that can be used with EVP_MAC_get_params(). See
180 OSSL_PARAM(3) for the use of OSSL_PARAM as a parameter descriptor.
181 EVP_MAC_gettable_ctx_params() and EVP_MAC_CTX_gettable_params() return
183 constant OSSL_PARAM arrays that describe the retrievable parameters
184 that can be used with EVP_MAC_CTX_get_params().
185 EVP_MAC_gettable_ctx_params() returns the parameters that can be
186 retrieved from the algorithm, whereas EVP_MAC_CTX_gettable_params()
187 returns the parameters that can be retrieved in the context's current
188 state. See OSSL_PARAM(3) for the use of OSSL_PARAM as a parameter
189 descriptor.
190 EVP_MAC_settable_ctx_params() and EVP_MAC_CTX_settable_params() return
192 constant OSSL_PARAM arrays that describe the settable parameters that
193 can be used with EVP_MAC_CTX_set_params().
194 EVP_MAC_settable_ctx_params() returns the parameters that can be
195 retrieved from the algorithm, whereas EVP_MAC_CTX_settable_params()
196 returns the parameters that can be retrieved in the context's current
197 state. See OSSL_PARAM(3) for the use of OSSL_PARAM as a parameter
198 descriptor.
199 Information functions
201 EVP_MAC_CTX_get_mac_size() returns the MAC output size for the given
202 context.
203 EVP_MAC_CTX_get_block_size() returns the MAC block size for the given
205 context. Not all MAC algorithms support this.
206 EVP_MAC_is_a() checks if the given mac is an implementation of an
208 algorithm that's identifiable with name.
209 EVP_MAC_get0_provider() returns the provider that holds the
211 implementation of the given mac.
212 EVP_MAC_do_all_provided() traverses all MAC implemented by all
214 activated providers in the given library context libctx, and for each
215 of the implementations, calls the given function fn with the
216 implementation method and the given arg as argument.
217 EVP_MAC_get0_name() return the name of the given MAC. For fetched MACs
219 with multiple names, only one of them is returned; it's recommended to
220 use EVP_MAC_names_do_all() instead.
221 EVP_MAC_names_do_all() traverses all names for mac, and calls fn with
223 each name and data.
224 EVP_MAC_get0_description() returns a description of the mac, meant for
226 display and human consumption. The description is at the discretion of
227 the mac implementation.
228
230 Parameters are identified by name as strings, and have an expected data
231 type and maximum size. OpenSSL has a set of macros for parameter names
232 it expects to see in its own MAC implementations. Here, we show all
233 three, the OpenSSL macro for the parameter name, the name in string
234 form, and a type description.
235 The standard parameter names are:
237 "key" (OSSL_MAC_PARAM_KEY) <octet string>
239 Its value is the MAC key as an array of bytes.
240 For MACs that use an underlying computation algorithm, the
242 algorithm must be set first, see parameter names "algorithm" below.
243 "iv" (OSSL_MAC_PARAM_IV) <octet string>
245 Some MAC implementations (GMAC) require an IV, this parameter sets
246 the IV.
247 "custom" (OSSL_MAC_PARAM_CUSTOM) <octet string>
249 Some MAC implementations (KMAC, BLAKE2) accept a Customization
250 String, this parameter sets the Customization String. The default
251 value is the empty string.
252 "salt" (OSSL_MAC_PARAM_SALT) <octet string>
254 This option is used by BLAKE2 MAC.
255 "xof" (OSSL_MAC_PARAM_XOF) <integer>
257 It's a simple flag, the value 0 or 1 are expected.
258 This option is used by KMAC.
260 "digest-noinit" (OSSL_MAC_PARAM_DIGEST_NOINIT) <integer>
262 A simple flag to set the MAC digest to not initialise the
263 implementation specific data. The value 0 or 1 is expected.
264 This option is used by HMAC.
266 "digest-oneshot" (OSSL_MAC_PARAM_DIGEST_ONESHOT) <integer>
268 A simple flag to set the MAC digest to be a oneshot operation. The
269 value 0 or 1 is expected.
270 This option is used by HMAC.
272 "properties" (OSSL_MAC_PARAM_PROPERTIES) <UTF8 string>
274 "digest" (OSSL_MAC_PARAM_DIGEST) <UTF8 string>
275 "cipher" (OSSL_MAC_PARAM_CIPHER) <UTF8 string>
276 For MAC implementations that use an underlying computation cipher
277 or digest, these parameters set what the algorithm should be.
278 The value is always the name of the intended algorithm, or the
280 properties.
281 Note that not all algorithms may support all digests. HMAC does
283 not support variable output length digests such as SHAKE128 or
284 SHAKE256.
285 "size" (OSSL_MAC_PARAM_SIZE) <unsigned integer>
287 For MAC implementations that support it, set the output size that
288 EVP_MAC_final() should produce. The allowed sizes vary between MAC
289 implementations, but must never exceed what can be given with a
290 size_t.
291 "tls-data-size" (OSSL_MAC_PARAM_TLS_DATA_SIZE) <unsigned integer>
293 This parameter is only supported by HMAC. If set then special
294 handling is activated for calculating the MAC of a received mac-
295 then-encrypt TLS record where variable length record padding has
296 been used (as in the case of CBC mode ciphersuites). The value
297 represents the total length of the record that is having the MAC
298 calculated including the received MAC and the record padding.
299 When used EVP_MAC_update must be called precisely twice. The first
301 time with the 13 bytes of TLS "header" data, and the second time
302 with the entire record including the MAC itself and any padding.
303 The entire record length must equal the value passed in the "tls-
304 data-size" parameter. The length passed in the datalen parameter to
305 EVP_MAC_update() should be equal to the length of the record after
306 the MAC and any padding has been removed.
307 All these parameters should be used before the calls to any of
309 EVP_MAC_init(), EVP_MAC_update() and EVP_MAC_final() for a full
310 computation. Anything else may give undefined results.
311
313 The MAC life-cycle is described in life_cycle-mac(7). In the future,
314 the transitions described there will be enforced. When this is done,
315 it will not be considered a breaking change to the API.
316 The usage of the parameter names "custom", "iv" and "salt" correspond
318 to the names used in the standard where the algorithm was defined.
319
321 EVP_MAC_fetch() returns a pointer to a newly fetched EVP_MAC, or NULL
322 if allocation failed.
323 EVP_MAC_up_ref() returns 1 on success, 0 on error.
325 EVP_MAC_names_do_all() returns 1 if the callback was called for all
327 names. A return value of 0 means that the callback was not called for
328 any names.
329 EVP_MAC_free() returns nothing at all.
331 EVP_MAC_is_a() returns 1 if the given method can be identified with the
333 given name, otherwise 0.
334 EVP_MAC_get0_name() returns a name of the MAC, or NULL on error.
336 EVP_MAC_get0_provider() returns a pointer to the provider for the MAC,
338 or NULL on error.
339 EVP_MAC_CTX_new() and EVP_MAC_CTX_dup() return a pointer to a newly
341 created EVP_MAC_CTX, or NULL if allocation failed.
342 EVP_MAC_CTX_free() returns nothing at all.
344 EVP_MAC_CTX_get_params() and EVP_MAC_CTX_set_params() return 1 on
346 success, 0 on error.
347 EVP_Q_mac() returns a pointer to the computed MAC value, or NULL on
349 error.
350 EVP_MAC_init(), EVP_MAC_update(), EVP_MAC_final(), and
352 EVP_MAC_finalXOF() return 1 on success, 0 on error.
353 EVP_MAC_CTX_get_mac_size() returns the expected output size, or 0 if it
355 isn't set. If it isn't set, a call to EVP_MAC_init() will set it.
356 EVP_MAC_CTX_get_block_size() returns the block size, or 0 if it isn't
358 set. If it isn't set, a call to EVP_MAC_init() will set it.
359 EVP_MAC_do_all_provided() returns nothing at all.
361
363 #include <stdlib.h>
364 #include <stdio.h>
365 #include <string.h>
366 #include <stdarg.h>
367 #include <unistd.h>
368 #include <openssl/evp.h>
370 #include <openssl/err.h>
371 #include <openssl/params.h>
372 int main() {
374 EVP_MAC *mac = EVP_MAC_fetch(NULL, getenv("MY_MAC"), NULL);
375 const char *cipher = getenv("MY_MAC_CIPHER");
376 const char *digest = getenv("MY_MAC_DIGEST");
377 const char *key = getenv("MY_KEY");
378 EVP_MAC_CTX *ctx = NULL;
379 unsigned char buf[4096];
381 size_t read_l;
382 size_t final_l;
383 size_t i;
385 OSSL_PARAM params[3];
387 size_t params_n = 0;
388 if (cipher != NULL)
390 params[params_n++] =
391 OSSL_PARAM_construct_utf8_string("cipher", (char*)cipher, 0);
392 if (digest != NULL)
393 params[params_n++] =
394 OSSL_PARAM_construct_utf8_string("digest", (char*)digest, 0);
395 params[params_n] = OSSL_PARAM_construct_end();
396 if (mac == NULL
398 || key == NULL
399 || (ctx = EVP_MAC_CTX_new(mac)) == NULL
400 || !EVP_MAC_init(ctx, (const unsigned char *)key, strlen(key),
401 params))
402 goto err;
403 while ( (read_l = read(STDIN_FILENO, buf, sizeof(buf))) > 0) {
405 if (!EVP_MAC_update(ctx, buf, read_l))
406 goto err;
407 }
408 if (!EVP_MAC_final(ctx, buf, &final_l, sizeof(buf)))
410 goto err;
411 printf("Result: ");
413 for (i = 0; i < final_l; i++)
414 printf("%02X", buf[i]);
415 printf("\n");
416 EVP_MAC_CTX_free(ctx);
418 EVP_MAC_free(mac);
419 exit(0);
420 err:
422 EVP_MAC_CTX_free(ctx);
423 EVP_MAC_free(mac);
424 fprintf(stderr, "Something went wrong\n");
425 ERR_print_errors_fp(stderr);
426 exit (1);
427 }
428 A run of this program, called with correct environment variables, can
430 look like this:
431 $ MY_MAC=cmac MY_KEY=secret0123456789 MY_MAC_CIPHER=aes-128-cbc \
433 LD_LIBRARY_PATH=. ./foo < foo.c
434 Result: C5C06683CD9DDEF904D754505C560A4E
435 (in this example, that program was stored in foo.c and compiled to
437 ./foo)
438
440 property(7) OSSL_PARAM(3), EVP_MAC-BLAKE2(7), EVP_MAC-CMAC(7),
441 EVP_MAC-GMAC(7), EVP_MAC-HMAC(7), EVP_MAC-KMAC(7), EVP_MAC-Siphash(7),
442 EVP_MAC-Poly1305(7), provider-mac(7), life_cycle-mac(7)
443
445 These functions were added in OpenSSL 3.0.
446
448 Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
449 Licensed under the Apache License 2.0 (the "License"). You may not use
451 this file except in compliance with the License. You can obtain a copy
452 in the file LICENSE in the source distribution or at
453 <https://www.openssl.org/source/license.html>.
4543.0.5 2022-07-05 EVP_MAC(3ossl)