5 EVP_MAC, EVP_MAC_fetch, EVP_MAC_up_ref, EVP_MAC_free, EVP_MAC_name,
6 EVP_MAC_provider, EVP_MAC_get_params, EVP_MAC_gettable_params,
7 EVP_MAC_CTX, EVP_MAC_CTX_new, EVP_MAC_CTX_free, EVP_MAC_CTX_dup,
8 EVP_MAC_CTX_mac, EVP_MAC_CTX_get_params, EVP_MAC_CTX_set_params,
9 EVP_MAC_size, EVP_MAC_init, EVP_MAC_update, EVP_MAC_final,
10 EVP_MAC_CTX_gettable_params, EVP_MAC_CTX_settable_params,
11 EVP_MAC_do_all_ex - EVP MAC routines
15 #include <openssl/evp.h>
17 typedef struct evp_mac_st EVP_MAC;
18 typedef struct evp_mac_ctx_st EVP_MAC_CTX;
20 EVP_MAC *EVP_MAC_fetch(OPENSSL_CTX *libctx, const char *algorithm,
21 const char *properties);
22 int EVP_MAC_up_ref(EVP_MAC *mac);
23 void EVP_MAC_free(EVP_MAC *mac);
24 const char *EVP_MAC_name(const EVP_MAC *mac);
25 const OSSL_PROVIDER *EVP_MAC_provider(const EVP_MAC *mac);
26 int EVP_MAC_get_params(EVP_MAC *mac, OSSL_PARAM params[]);
28 EVP_MAC_CTX *EVP_MAC_CTX_new(EVP_MAC *mac);
29 void EVP_MAC_CTX_free(EVP_MAC_CTX *ctx);
30 EVP_MAC_CTX *EVP_MAC_CTX_dup(const EVP_MAC_CTX *src);
31 EVP_MAC *EVP_MAC_CTX_mac(EVP_MAC_CTX *ctx);
32 int EVP_MAC_CTX_get_params(EVP_MAC_CTX *ctx, OSSL_PARAM params[]);
33 int EVP_MAC_CTX_set_params(EVP_MAC_CTX *ctx, const OSSL_PARAM params[]);
35 size_t EVP_MAC_size(EVP_MAC_CTX *ctx);
36 int EVP_MAC_init(EVP_MAC_CTX *ctx);
37 int EVP_MAC_update(EVP_MAC_CTX *ctx, const unsigned char *data, size_t datalen);
38 int EVP_MAC_final(EVP_MAC_CTX *ctx,
39 unsigned char *out, size_t *outl, size_t outsize);
41 const OSSL_PARAM *EVP_MAC_gettable_params(const EVP_MAC *mac);
42 const OSSL_PARAM *EVP_MAC_CTX_gettable_params(const EVP_MAC *mac);
43 const OSSL_PARAM *EVP_MAC_CTX_settable_params(const EVP_MAC *mac);
45 void EVP_MAC_do_all_ex(OPENSSL_CTX *libctx,
46 void (*fn)(EVP_MAC *mac, void *arg),
51 These types and functions help the application to calculate MACs of
52 different types and with different underlying algorithms if there are
55 MACs are a bit complex insofar that some of them use other algorithms
56 for actual computation. HMAC uses a digest, and CMAC uses a cipher.
57 Therefore, there are sometimes two contexts to keep track of, one for
58 the MAC algorithm itself and one for the underlying computation
59 algorithm if there is one.
61 To make things less ambiguous, this manual talks about a "context" or
62 "MAC context", which is to denote the MAC level context, and about a
63 "underlying context", or "computation context", which is to denote the
64 context for the underlying computation algorithm if there is one.
68 B<EVP_MAC> is a type that holds the implementation of a MAC.
70 B<EVP_MAC_CTX> is a context type that holds internal MAC information
71 as well as a reference to a computation context, for those MACs that
72 rely on an underlying computation algorithm.
74 =head2 Algorithm implementation fetching
76 EVP_MAC_fetch() fetches an implementation of a MAC I<algorithm>, given
77 a library context I<libctx> and a set of I<properties>.
78 See L<provider(7)/Fetching algorithms> for further information.
80 The returned value must eventually be freed with
83 EVP_MAC_up_ref() increments the reference count of an already fetched
86 EVP_MAC_free() frees a fetched algorithm.
87 NULL is a valid parameter, for which this function is a no-op.
89 =head2 Context manipulation functions
91 EVP_MAC_CTX_new() creates a new context for the MAC type I<mac>.
92 The created context can then be used with most other functions
95 EVP_MAC_CTX_free() frees the contents of the context, including an
96 underlying context if there is one, as well as the context itself.
97 NULL is a valid parameter, for which this function is a no-op.
99 EVP_MAC_CTX_dup() duplicates the I<src> context and returns a newly allocated
102 EVP_MAC_CTX_mac() returns the B<EVP_MAC> associated with the context
105 =head2 Computing functions
107 EVP_MAC_init() sets up the underlying context with information given
108 through diverse controls.
109 This should be called before calling EVP_MAC_update() and
112 EVP_MAC_update() adds I<datalen> bytes from I<data> to the MAC input.
114 EVP_MAC_final() does the final computation and stores the result in
115 the memory pointed at by I<out> of size I<outsize>, and sets the number
116 of bytes written in I<*outl> at.
117 If I<out> is B<NULL> or I<outsize> is too small, then no computation
119 To figure out what the output length will be and allocate space for it
120 dynamically, simply call with I<out> being B<NULL> and I<outl>
121 pointing at a valid location, then allocate space and make a second
122 call with I<out> pointing at the allocated space.
124 EVP_MAC_get_params() retrieves details about the implementation
126 The set of parameters given with I<params> determine exactly what
127 parameters should be retrieved.
128 Note that a parameter that is unknown in the underlying context is
131 EVP_MAC_CTX_get_params() retrieves chosen parameters, given the
132 context I<ctx> and its underlying context.
133 The set of parameters given with I<params> determine exactly what
134 parameters should be retrieved.
135 Note that a parameter that is unknown in the underlying context is
138 EVP_MAC_CTX_set_params() passes chosen parameters to the underlying
139 context, given a context I<ctx>.
140 The set of parameters given with I<params> determine exactly what
141 parameters are passed down.
142 Note that a parameter that is unknown in the underlying context is
144 Also, what happens when a needed parameter isn't passed down is
145 defined by the implementation.
147 EVP_MAC_gettable_params(), EVP_MAC_CTX_gettable_params() and
148 EVP_MAC_CTX_settable_params() get a constant B<OSSL_PARAM> array that
149 decribes the retrievable and settable parameters, i.e. parameters that
150 can be used with EVP_MAC_CTX_get_params(), EVP_MAC_CTX_get_params()
151 and EVP_MAC_CTX_set_params(), respectively.
152 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
154 =head2 Information functions
156 EVP_MAC_size() returns the MAC output size for the given context.
158 EVP_MAC_name() returns the name of the given MAC implementation.
160 EVP_MAC_provider() returns the provider that holds the implementation
163 EVP_MAC_do_all_ex() traverses all MAC implemented by all activated
164 providers in the given library context I<libctx>, and for each of the
165 implementations, calls the given function I<fn> with the implementation method
166 and the given I<arg> as argument.
168 =head1 PARAMETER NAMES
170 The standard parameter names are:
174 =item OSSL_MAC_PARAM_KEY ("key") <octet string>
176 Its value is the MAC key as an array of bytes.
178 For MACs that use an underlying computation algorithm, the algorithm
179 must be set first, see parameter names "algorithm" below.
181 =item OSSL_MAC_PARAM_IV ("iv") <octet string>
183 Some MAC implementations require an IV, this parameter sets the IV.
185 =item OSSL_MAC_PARAM_CUSTOM ("custom") <octet string>
187 Some MAC implementations (KMAC, BLAKE2) accept a Customization String,
188 this parameter sets the Customization String. The default value is the
191 =item OSSL_MAC_PARAM_SALT ("salt") <octet string>
193 This option is used by BLAKE2 MAC.
195 =item OSSL_MAC_PARAM_XOF ("xof") <int>
197 It's a simple flag, the value 0 or 1 are expected.
199 This option is used by KMAC.
201 =item OSSL_MAC_PARAM_FLAGS ("flags") <int>
203 These will set the MAC flags to the given numbers.
204 Some MACs do not support this option.
206 =item OSSL_MAC_PARAM_ENGINE ("engine") <utf8string>
208 =item OSSL_MAC_PARAM_MD ("md") <utf8string>
210 =item OSSL_MAC_PARAM_DIGEST ("digest") <utf8string>
212 =item OSSL_MAC_PARAM_CIPHER ("cipher") <utf8string>
214 =item OSSL_MAC_PARAM_ALGORITHM ("algorithm") <utf8string>
216 For MAC implementations that use an underlying computation algorithm,
217 these parameters set what the algorithm should be, and the engine that
218 implements the algorithm if needed.
220 The value is always the name of the intended engine or algorithm.
222 Note that not all algorithms may support all digests.
223 HMAC does not support variable output length digests such as SHAKE128
226 Also note that OSSL_MAC_PARAM_ALGORITHM can be use generically instead
227 of OSSL_MAC_PARAM_MD, OSSL_MAC_PARAM_DIGEST or OSSL_MAC_PARAM_CIPHER,
228 and that OSSL_MAC_PARAM_MD and OSSL_MAC_PARAM_DIGEST are also interchangable.
230 =item OSSL_MAC_PARAM_SIZE <unsigned int>
232 For MAC implementations that support it, set the output size that
233 EVP_MAC_final() should produce.
234 The allowed sizes vary between MAC implementations.
238 All these parameters should be used before the calls to any of
239 EVP_MAC_init(), EVP_MAC_update() and EVP_MAC_final() for a full
241 Anything else may give undefined results.
245 EVP_MAC_fetch() returns a pointer to a newly fetched EVP_MAC, or
246 NULL if allocation failed.
248 EVP_MAC_up_ref() returns 1 on success, 0 on error.
250 EVP_MAC_free() returns nothing at all.
252 EVP_MAC_name() returns the name of the MAC, or NULL if NULL was
255 EVP_MAC_provider() returns a pointer to the provider for the MAC, or
258 EVP_MAC_CTX_new() and EVP_MAC_CTX_dup() return a pointer to a newly
259 created EVP_MAC_CTX, or NULL if allocation failed.
261 EVP_MAC_CTX_free() returns nothing at all.
263 EVP_MAC_CTX_get_params() and EVP_MAC_CTX_set_params() return 1 on
266 EVP_MAC_init(), EVP_MAC_update(), and EVP_MAC_final() return 1 on success, 0
269 EVP_MAC_size() returns the expected output size, or 0 if it isn't
271 If it isn't set, a call to EVP_MAC_init() should get it set.
273 EVP_MAC_do_all_ex() returns nothing at all.
283 #include <openssl/evp.h>
284 #include <openssl/err.h>
285 #include <openssl/params.h>
288 EVP_MAC *mac = EVP_MAC_fetch(NULL, getenv("MY_MAC"), NULL);
289 const char *cipher = getenv("MY_MAC_CIPHER");
290 const char *digest = getenv("MY_MAC_DIGEST");
291 const char *key = getenv("MY_KEY");
292 EVP_MAC_CTX *ctx = NULL;
294 unsigned char buf[4096];
300 OSSL_PARAM params[4];
305 OSSL_PARAM_construct_utf8_string("cipher", cipher,
306 strlen(cipher) + 1, NULL);
309 OSSL_PARAM_construct_utf8_string("digest", digest,
310 strlen(digest) + 1, NULL);
312 OSSL_PARAM_construct_octet_string("key", key, strlen(key), NULL);
313 params[params_n] = OSSL_PARAM_construct_end();
317 || (ctx = EVP_MAC_CTX_new(mac)) == NULL
318 || EVP_MAC_CTX_set_params(ctx, params) <= 0)
321 if (!EVP_MAC_init(ctx))
324 while ( (read_l = read(STDIN_FILENO, buf, sizeof(buf))) < 0) {
325 if (!EVP_MAC_update(ctx, buf, read_l))
329 if (!EVP_MAC_final(ctx, buf, &final_l))
333 for (i = 0; i < final_l; i++)
334 printf("%02X", buf[i]);
337 EVP_MAC_CTX_free(ctx);
342 EVP_MAC_CTX_free(ctx);
344 fprintf(stderr, "Something went wrong\n");
345 ERR_print_errors_fp(stderr);
349 A run of this program, called with correct environment variables, can
352 $ MY_MAC=cmac MY_KEY=secret0123456789 MY_MAC_CIPHER=aes-128-cbc \
353 LD_LIBRARY_PATH=. ./foo < foo.c
354 Result: ECCAAFF041B22A2299EB90A1B53B6D45
356 (in this example, that program was stored in F<foo.c> and compiled to
363 L<EVP_MAC_BLAKE2(7)>,
368 L<EVP_MAC_SIPHASH(7)>,
369 L<EVP_MAC_POLY1305(7)>
373 These functions were added in OpenSSL 3.0.
377 Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
379 Licensed under the Apache License 2.0 (the "License"). You may not use
380 this file except in compliance with the License. You can obtain a copy
381 in the file LICENSE in the source distribution or at
382 L<https://www.openssl.org/source/license.html>.