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(3) 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().
180 EVP_MAC_gettable_ctx_params() and EVP_MAC_CTX_gettable_params() return
182 constant OSSL_PARAM(3) arrays that describe the retrievable parameters
183 that can be used with EVP_MAC_CTX_get_params().
184 EVP_MAC_gettable_ctx_params() returns the parameters that can be
185 retrieved from the algorithm, whereas EVP_MAC_CTX_gettable_params()
186 returns the parameters that can be retrieved in the context's current
187 state.
188 EVP_MAC_settable_ctx_params() and EVP_MAC_CTX_settable_params() return
190 constant OSSL_PARAM(3) arrays that describe the settable parameters
191 that can be used with EVP_MAC_CTX_set_params().
192 EVP_MAC_settable_ctx_params() returns the parameters that can be
193 retrieved from the algorithm, whereas EVP_MAC_CTX_settable_params()
194 returns the parameters that can be retrieved in the context's current
195 state.
196 Information functions
198 EVP_MAC_CTX_get_mac_size() returns the MAC output size for the given
199 context.
200 EVP_MAC_CTX_get_block_size() returns the MAC block size for the given
202 context. Not all MAC algorithms support this.
203 EVP_MAC_is_a() checks if the given mac is an implementation of an
205 algorithm that's identifiable with name.
206 EVP_MAC_get0_provider() returns the provider that holds the
208 implementation of the given mac.
209 EVP_MAC_do_all_provided() traverses all MAC implemented by all
211 activated providers in the given library context libctx, and for each
212 of the implementations, calls the given function fn with the
213 implementation method and the given arg as argument.
214 EVP_MAC_get0_name() return the name of the given MAC. For fetched MACs
216 with multiple names, only one of them is returned; it's recommended to
217 use EVP_MAC_names_do_all() instead.
218 EVP_MAC_names_do_all() traverses all names for mac, and calls fn with
220 each name and data.
221 EVP_MAC_get0_description() returns a description of the mac, meant for
223 display and human consumption. The description is at the discretion of
224 the mac implementation.
225
227 Parameters are identified by name as strings, and have an expected data
228 type and maximum size. OpenSSL has a set of macros for parameter names
229 it expects to see in its own MAC implementations. Here, we show all
230 three, the OpenSSL macro for the parameter name, the name in string
231 form, and a type description.
232 The standard parameter names are:
234 "key" (OSSL_MAC_PARAM_KEY) <octet string>
236 Its value is the MAC key as an array of bytes.
237 For MACs that use an underlying computation algorithm, the
239 algorithm must be set first, see parameter names "algorithm" below.
240 "iv" (OSSL_MAC_PARAM_IV) <octet string>
242 Some MAC implementations (GMAC) require an IV, this parameter sets
243 the IV.
244 "custom" (OSSL_MAC_PARAM_CUSTOM) <octet string>
246 Some MAC implementations (KMAC, BLAKE2) accept a Customization
247 String, this parameter sets the Customization String. The default
248 value is the empty string.
249 "salt" (OSSL_MAC_PARAM_SALT) <octet string>
251 This option is used by BLAKE2 MAC.
252 "xof" (OSSL_MAC_PARAM_XOF) <integer>
254 It's a simple flag, the value 0 or 1 are expected.
255 This option is used by KMAC.
257 "digest-noinit" (OSSL_MAC_PARAM_DIGEST_NOINIT) <integer>
259 A simple flag to set the MAC digest to not initialise the
260 implementation specific data. The value 0 or 1 is expected.
261 This option is used by HMAC.
263 "digest-oneshot" (OSSL_MAC_PARAM_DIGEST_ONESHOT) <integer>
265 A simple flag to set the MAC digest to be a oneshot operation. The
266 value 0 or 1 is expected.
267 This option is used by HMAC.
269 "properties" (OSSL_MAC_PARAM_PROPERTIES) <UTF8 string>
271 "digest" (OSSL_MAC_PARAM_DIGEST) <UTF8 string>
272 "cipher" (OSSL_MAC_PARAM_CIPHER) <UTF8 string>
273 For MAC implementations that use an underlying computation cipher
274 or digest, these parameters set what the algorithm should be.
275 The value is always the name of the intended algorithm, or the
277 properties.
278 Note that not all algorithms may support all digests. HMAC does
280 not support variable output length digests such as SHAKE128 or
281 SHAKE256.
282 "size" (OSSL_MAC_PARAM_SIZE) <unsigned integer>
284 For MAC implementations that support it, set the output size that
285 EVP_MAC_final() should produce. The allowed sizes vary between MAC
286 implementations, but must never exceed what can be given with a
287 size_t.
288 "tls-data-size" (OSSL_MAC_PARAM_TLS_DATA_SIZE) <unsigned integer>
290 This parameter is only supported by HMAC. If set then special
291 handling is activated for calculating the MAC of a received mac-
292 then-encrypt TLS record where variable length record padding has
293 been used (as in the case of CBC mode ciphersuites). The value
294 represents the total length of the record that is having the MAC
295 calculated including the received MAC and the record padding.
296 When used EVP_MAC_update must be called precisely twice. The first
298 time with the 13 bytes of TLS "header" data, and the second time
299 with the entire record including the MAC itself and any padding.
300 The entire record length must equal the value passed in the "tls-
301 data-size" parameter. The length passed in the datalen parameter to
302 EVP_MAC_update() should be equal to the length of the record after
303 the MAC and any padding has been removed.
304 All these parameters should be used before the calls to any of
306 EVP_MAC_init(), EVP_MAC_update() and EVP_MAC_final() for a full
307 computation. Anything else may give undefined results.
308
310 The MAC life-cycle is described in life_cycle-mac(7). In the future,
311 the transitions described there will be enforced. When this is done,
312 it will not be considered a breaking change to the API.
313 The usage of the parameter names "custom", "iv" and "salt" correspond
315 to the names used in the standard where the algorithm was defined.
316
318 EVP_MAC_fetch() returns a pointer to a newly fetched EVP_MAC, or NULL
319 if allocation failed.
320 EVP_MAC_up_ref() returns 1 on success, 0 on error.
322 EVP_MAC_names_do_all() returns 1 if the callback was called for all
324 names. A return value of 0 means that the callback was not called for
325 any names.
326 EVP_MAC_free() returns nothing at all.
328 EVP_MAC_is_a() returns 1 if the given method can be identified with the
330 given name, otherwise 0.
331 EVP_MAC_get0_name() returns a name of the MAC, or NULL on error.
333 EVP_MAC_get0_provider() returns a pointer to the provider for the MAC,
335 or NULL on error.
336 EVP_MAC_CTX_new() and EVP_MAC_CTX_dup() return a pointer to a newly
338 created EVP_MAC_CTX, or NULL if allocation failed.
339 EVP_MAC_CTX_free() returns nothing at all.
341 EVP_MAC_CTX_get_params() and EVP_MAC_CTX_set_params() return 1 on
343 success, 0 on error.
344 EVP_Q_mac() returns a pointer to the computed MAC value, or NULL on
346 error.
347 EVP_MAC_init(), EVP_MAC_update(), EVP_MAC_final(), and
349 EVP_MAC_finalXOF() return 1 on success, 0 on error.
350 EVP_MAC_CTX_get_mac_size() returns the expected output size, or 0 if it
352 isn't set. If it isn't set, a call to EVP_MAC_init() will set it.
353 EVP_MAC_CTX_get_block_size() returns the block size, or 0 if it isn't
355 set. If it isn't set, a call to EVP_MAC_init() will set it.
356 EVP_MAC_do_all_provided() returns nothing at all.
358
360 #include <stdlib.h>
361 #include <stdio.h>
362 #include <string.h>
363 #include <stdarg.h>
364 #include <unistd.h>
365 #include <openssl/evp.h>
367 #include <openssl/err.h>
368 #include <openssl/params.h>
369 int main() {
371 EVP_MAC *mac = EVP_MAC_fetch(NULL, getenv("MY_MAC"), NULL);
372 const char *cipher = getenv("MY_MAC_CIPHER");
373 const char *digest = getenv("MY_MAC_DIGEST");
374 const char *key = getenv("MY_KEY");
375 EVP_MAC_CTX *ctx = NULL;
376 unsigned char buf[4096];
378 size_t read_l;
379 size_t final_l;
380 size_t i;
382 OSSL_PARAM params[3];
384 size_t params_n = 0;
385 if (cipher != NULL)
387 params[params_n++] =
388 OSSL_PARAM_construct_utf8_string("cipher", (char*)cipher, 0);
389 if (digest != NULL)
390 params[params_n++] =
391 OSSL_PARAM_construct_utf8_string("digest", (char*)digest, 0);
392 params[params_n] = OSSL_PARAM_construct_end();
393 if (mac == NULL
395 || key == NULL
396 || (ctx = EVP_MAC_CTX_new(mac)) == NULL
397 || !EVP_MAC_init(ctx, (const unsigned char *)key, strlen(key),
398 params))
399 goto err;
400 while ( (read_l = read(STDIN_FILENO, buf, sizeof(buf))) > 0) {
402 if (!EVP_MAC_update(ctx, buf, read_l))
403 goto err;
404 }
405 if (!EVP_MAC_final(ctx, buf, &final_l, sizeof(buf)))
407 goto err;
408 printf("Result: ");
410 for (i = 0; i < final_l; i++)
411 printf("%02X", buf[i]);
412 printf("\n");
413 EVP_MAC_CTX_free(ctx);
415 EVP_MAC_free(mac);
416 exit(0);
417 err:
419 EVP_MAC_CTX_free(ctx);
420 EVP_MAC_free(mac);
421 fprintf(stderr, "Something went wrong\n");
422 ERR_print_errors_fp(stderr);
423 exit (1);
424 }
425 A run of this program, called with correct environment variables, can
427 look like this:
428 $ MY_MAC=cmac MY_KEY=secret0123456789 MY_MAC_CIPHER=aes-128-cbc \
430 LD_LIBRARY_PATH=. ./foo < foo.c
431 Result: C5C06683CD9DDEF904D754505C560A4E
432 (in this example, that program was stored in foo.c and compiled to
434 ./foo)
435
437 property(7) OSSL_PARAM(3), EVP_MAC-BLAKE2(7), EVP_MAC-CMAC(7),
438 EVP_MAC-GMAC(7), EVP_MAC-HMAC(7), EVP_MAC-KMAC(7), EVP_MAC-Siphash(7),
439 EVP_MAC-Poly1305(7), provider-mac(7), life_cycle-mac(7)
440
442 These functions were added in OpenSSL 3.0.
443
445 Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
446 Licensed under the Apache License 2.0 (the "License"). You may not use
448 this file except in compliance with the License. You can obtain a copy
449 in the file LICENSE in the source distribution or at
450 <https://www.openssl.org/source/license.html>.
4513.0.9 2023-07-27 EVP_MAC(3ossl)