5 EVP_MD_fetch, EVP_MD_up_ref, EVP_MD_free,
6 EVP_MD_get_params, EVP_MD_gettable_params,
7 EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy,
8 EVP_MD_CTX_copy_ex, EVP_MD_CTX_ctrl,
9 EVP_MD_CTX_set_params, EVP_MD_CTX_get_params,
10 EVP_MD_CTX_settable_params, EVP_MD_CTX_gettable_params,
11 EVP_MD_CTX_set_flags, EVP_MD_CTX_clear_flags, EVP_MD_CTX_test_flags,
12 EVP_Digest, EVP_DigestInit_ex, EVP_DigestInit, EVP_DigestUpdate,
13 EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
14 EVP_MD_name, EVP_MD_provider,
15 EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_flags,
17 EVP_MD_CTX_md, EVP_MD_CTX_type, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
18 EVP_MD_CTX_md_data, EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn,
20 EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
21 EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_set_pkey_ctx,
27 #include <openssl/evp.h>
29 EVP_MD *EVP_MD_fetch(OPENSSL_CTX *ctx, const char *algorithm,
30 const char *properties);
31 int EVP_MD_up_ref(EVP_MD *md);
32 void EVP_MD_free(EVP_MD *md);
33 int EVP_MD_get_params(const EVP_MD *digest, OSSL_PARAM params[]);
34 const OSSL_PARAM *EVP_MD_gettable_params(const EVP_MD *digest);
35 EVP_MD_CTX *EVP_MD_CTX_new(void);
36 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
37 void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
38 void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
39 int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
40 int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
41 const OSSL_PARAM *EVP_MD_CTX_settable_params(const EVP_MD *digest);
42 const OSSL_PARAM *EVP_MD_CTX_gettable_params(const EVP_MD *digest);
43 void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
44 void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
45 int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
47 int EVP_Digest(const void *data, size_t count, unsigned char *md,
48 unsigned int *size, const EVP_MD *type, ENGINE *impl);
49 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
50 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
51 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
52 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
54 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
56 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
57 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
59 int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
61 const char *EVP_MD_name(const EVP_MD *md);
62 const OSSL_PROVIDER *EVP_MD_provider(const EVP_MD *md);
63 int EVP_MD_type(const EVP_MD *md);
64 int EVP_MD_pkey_type(const EVP_MD *md);
65 int EVP_MD_size(const EVP_MD *md);
66 int EVP_MD_block_size(const EVP_MD *md);
67 unsigned long EVP_MD_flags(const EVP_MD *md);
69 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
70 const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
71 int EVP_MD_CTX_size(const EVP_MD_CTX *ctx);
72 int EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);
73 int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);
74 void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
75 int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
76 const void *data, size_t count);
77 void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
78 int (*update)(EVP_MD_CTX *ctx,
79 const void *data, size_t count));
81 const EVP_MD *EVP_md_null(void);
83 const EVP_MD *EVP_get_digestbyname(const char *name);
84 const EVP_MD *EVP_get_digestbynid(int type);
85 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
87 EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);
88 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
90 void EVP_MD_do_all_ex(OPENSSL_CTX *libctx,
91 void (*fn)(EVP_MD *mac, void *arg),
96 The EVP digest routines are a high level interface to message digests,
97 and should be used instead of the digest-specific functions.
99 The B<EVP_MD> type is a structure for digest method implementation.
105 Fetches the digest implementation for the given B<algorithm> from any
106 provider offering it, within the criteria given by the B<properties>.
107 See L<provider(7)/Fetching algorithms> for further information.
109 The returned value must eventually be freed with EVP_MD_free().
111 Fetched B<EVP_MD> structures are reference counted.
113 =item EVP_MD_up_ref()
115 Increments the reference count for an B<EVP_MD> structure.
119 Decrements the reference count for the fetched B<EVP_MD> structure.
120 If the reference count drops to 0 then the structure is freed.
122 =item EVP_MD_CTX_new()
124 Allocates and returns a digest context.
126 =item EVP_MD_CTX_reset()
128 Resets the digest context B<ctx>. This can be used to reuse an already
131 =item EVP_MD_CTX_free()
133 Cleans up digest context B<ctx> and frees up the space allocated to it.
135 =item EVP_MD_CTX_ctrl()
137 This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
138 is the mechanism that should be used to set and get parameters that are used by
140 Performs digest-specific control actions on context B<ctx>. The control command
141 is indicated in B<cmd> and any additional arguments in B<p1> and B<p2>.
142 EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex(). Other restrictions
143 may apply depending on the control type and digest implementation.
144 See L</CONTROLS> below for more information.
146 =item EVP_MD_get_params()
148 Retrieves the requested list of B<params> from a MD B<md>.
149 See L</PARAMETERS> below for more information.
151 =item EVP_MD_CTX_get_params()
153 Retrieves the requested list of B<params> from a MD context B<ctx>.
154 See L</PARAMETERS> below for more information.
156 =item EVP_MD_CTX_set_params()
158 Sets the list of B<params> into a MD context B<ctx>.
159 See L</PARAMETERS> below for more information.
161 =item EVP_MD_gettable_params(), EVP_MD_CTX_gettable_params(),
162 EVP_MD_CTX_settable_params()
164 Get a B<OSSL_PARAM> array that describes the retrievable and settable
165 parameters, i.e. parameters that can be used with EVP_MD_get_params(),
166 EVP_MD_CTX_get_params() and EVP_MD_CTX_set_params(), respectively.
167 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
169 =item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
171 Sets, clears and tests B<ctx> flags. See L</FLAGS> below for more information.
175 A wrapper around the Digest Init_ex, Update and Final_ex functions.
176 Hashes B<count> bytes of data at B<data> using a digest B<type> from ENGINE
177 B<impl>. The digest value is placed in B<md> and its length is written at B<size>
178 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
179 If B<impl> is NULL the default implementation of digest B<type> is used.
181 =item EVP_DigestInit_ex()
183 Sets up digest context B<ctx> to use a digest B<type>.
184 B<type> is typically supplied by a function such as EVP_sha1(), or a
185 value explicitly fetched with EVP_MD_fetch().
187 If B<impl> is non-NULL, its implementation of the digest B<type> is used if
188 there is one, and if not, the default implementation is used.
190 =item EVP_DigestUpdate()
192 Hashes B<cnt> bytes of data at B<d> into the digest context B<ctx>. This
193 function can be called several times on the same B<ctx> to hash additional
196 =item EVP_DigestFinal_ex()
198 Retrieves the digest value from B<ctx> and places it in B<md>. If the B<s>
199 parameter is not NULL then the number of bytes of data written (i.e. the
200 length of the digest) will be written to the integer at B<s>, at most
201 B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
202 no additional calls to EVP_DigestUpdate() can be made, but
203 EVP_DigestInit_ex() can be called to initialize a new digest operation.
205 =item EVP_DigestFinalXOF()
207 Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
208 It retrieves the digest value from B<ctx> and places it in B<len>-sized <B>md.
209 After calling this function no additional calls to EVP_DigestUpdate() can be
210 made, but EVP_DigestInit_ex() can be called to initialize a new operation.
212 =item EVP_MD_CTX_copy_ex()
214 Can be used to copy the message digest state from B<in> to B<out>. This is
215 useful if large amounts of data are to be hashed which only differ in the last
218 =item EVP_DigestInit()
220 Behaves in the same way as EVP_DigestInit_ex() except it always uses the
221 default digest implementation.
223 =item EVP_DigestFinal()
225 Similar to EVP_DigestFinal_ex() except the digest context B<ctx> is
226 automatically cleaned up.
228 =item EVP_MD_CTX_copy()
230 Similar to EVP_MD_CTX_copy_ex() except the destination B<out> does not have to
236 Return the name of the given message digest.
238 =item EVP_MD_provider()
240 Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given
246 Return the size of the message digest when passed an B<EVP_MD> or an
247 B<EVP_MD_CTX> structure, i.e. the size of the hash.
249 =item EVP_MD_block_size(),
250 EVP_MD_CTX_block_size()
252 Return the block size of the message digest when passed an B<EVP_MD> or an
253 B<EVP_MD_CTX> structure.
258 Return the NID of the OBJECT IDENTIFIER representing the given message digest
259 when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
260 returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
262 =item EVP_MD_CTX_md_data()
264 Return the digest method private data for the passed B<EVP_MD_CTX>.
265 The space is allocated by OpenSSL and has the size originally set with
266 EVP_MD_meth_set_app_datasize().
268 =item EVP_MD_CTX_md()
270 Returns the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
271 will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex() (or
272 other similar function) when the EVP_MD_CTX was first initialised. Note that
273 where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
274 this function will not have its reference count incremented and therefore it
275 should not be used after the EVP_MD_CTX is freed.
277 =item EVP_MD_CTX_set_update_fn()
279 Sets the update function for B<ctx> to B<update>.
280 This is the function that is called by EVP_DigestUpdate. If not set, the
281 update function from the B<EVP_MD> type specified at initialization is used.
283 =item EVP_MD_CTX_update_fn()
285 Returns the update function for B<ctx>.
289 Returns the B<md> flags. Note that these are different from the B<EVP_MD_CTX>
290 ones. See L<EVP_MD_meth_set_flags(3)> for more information.
292 =item EVP_MD_pkey_type()
294 Returns the NID of the public key signing algorithm associated with this
295 digest. For example EVP_sha1() is associated with RSA so this will return
296 B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
297 longer linked this function is only retained for compatibility reasons.
301 A "null" message digest that does nothing: i.e. the hash it returns is of zero
304 =item EVP_get_digestbyname(),
305 EVP_get_digestbynid(),
306 EVP_get_digestbyobj()
308 Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
309 B<ASN1_OBJECT> structure respectively.
311 =item EVP_MD_CTX_pkey_ctx()
313 Returns the B<EVP_PKEY_CTX> assigned to B<ctx>. The returned pointer should not
314 be freed by the caller.
316 =item EVP_MD_CTX_set_pkey_ctx()
318 Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
319 a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
320 L<EVP_DigestVerifyInit(3)>. The B<pctx> passed to this function should be freed
321 by the caller. A NULL B<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
322 assigned to B<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
323 depends on how the B<EVP_PKEY_CTX> is created.
325 =item EVP_MD_do_all_ex()
327 Traverses all messages digests implemented by all activated providers
328 in the given library context I<libctx>, and for each of the implementations,
329 calls the given function I<fn> with the implementation method and the given
336 See L<OSSL_PARAM(3)> for information about passing parameters.
338 EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
342 =item OSSL_PARAM_DIGEST_KEY_XOFLEN <unsigned integer>
344 Sets the digest length for extendable output functions.
345 It is used by the SHAKE algorithm and should not exceed what can be given
348 =item OSSL_PARAM_DIGEST_KEY_PAD_TYPE <integer>
351 It is used by the MDC2 algorithm.
355 EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
359 =item OSSL_PARAM_DIGEST_KEY_MICALG <UTF8 string>.
361 Gets the digest Message Integrity Check algorithm string. This is used when
362 creating S/MIME multipart/signed messages, as specified in RFC 3851.
363 It may be used by external engines or providers.
369 EVP_MD_CTX_ctrl() can be used to send the following standard controls:
373 =item EVP_MD_CTRL_MICALG
375 Gets the digest Message Integrity Check algorithm string. This is used when
376 creating S/MIME multipart/signed messages, as specified in RFC 3851.
377 The string value is written to B<p2>.
379 =item EVP_MD_CTRL_XOF_LEN
381 This control sets the digest length for extendable output functions to B<p1>.
382 Sending this control directly should not be necessary, the use of
383 C<EVP_DigestFinalXOF()> is preferred.
384 Currently used by SHAKE.
390 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
391 can be used the manipulate and test these B<EVP_MD_CTX> flags:
395 =item EVP_MD_CTX_FLAG_ONESHOT
397 This flag instructs the digest to optimize for one update only, if possible.
399 =for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
401 =for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
403 =for comment We currently avoid documenting flags that are only bit holder:
404 EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
406 =item EVP_MD_CTX_FLAG_NO_INIT
408 This flag instructs EVP_DigestInit() and similar not to initialise the
409 implementation specific data.
411 =item EVP_MD_CTX_FLAG_FINALISE
413 Some functions such as EVP_DigestSign only finalise copies of internal
414 contexts so additional data can be included after the finalisation call.
415 This is inefficient if this functionality is not required, and can be
416 disabled with this flag.
426 Returns a pointer to a B<EVP_MD> for success or NULL for failure.
428 =item EVP_MD_up_ref()
430 Returns 1 for success or 0 for failure.
432 =item EVP_DigestInit_ex(),
437 success and 0 for failure.
439 =item EVP_MD_CTX_ctrl()
441 Returns 1 if successful or 0 for failure.
443 =item EVP_MD_CTX_set_params(),
444 EVP_MD_CTX_get_params()
446 Returns 1 if successful or 0 for failure.
448 =item EVP_MD_CTX_settable_params(),
449 EVP_MD_CTX_gettable_params()
451 Return an array of constant B<OSSL_PARAM>s, or NULL if there is none
454 =item EVP_MD_CTX_copy_ex()
456 Returns 1 if successful or 0 for failure.
461 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
467 EVP_MD_CTX_block_size()
469 Returns the digest or block size in bytes.
473 Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
475 =item EVP_get_digestbyname(),
476 EVP_get_digestbynid(),
477 EVP_get_digestbyobj()
479 Returns either an B<EVP_MD> structure or NULL if an error occurs.
481 =item EVP_MD_CTX_set_pkey_ctx()
483 This function has no return value.
489 The B<EVP> interface to message digests should almost always be used in
490 preference to the low level interfaces. This is because the code then becomes
491 transparent to the digest used and much more flexible.
493 New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
494 digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
495 are still in common use.
497 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
498 set to NULL to use the default digest implementation.
500 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
501 obsolete but are retained to maintain compatibility with existing code. New
502 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
503 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
504 instead of initializing and cleaning it up on each call and allow non default
505 implementations of digests to be specified.
507 If digest contexts are not cleaned up after use,
508 memory leaks will occur.
510 EVP_MD_CTX_name(), EVP_MD_CTX_size(), EVP_MD_CTX_block_size(),
511 EVP_MD_CTX_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are defined
514 EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
519 This example digests the data "Test Message\n" and "Hello World\n", using the
520 digest name passed on the command line.
524 #include <openssl/evp.h>
526 int main(int argc, char *argv[])
530 char mess1[] = "Test Message\n";
531 char mess2[] = "Hello World\n";
532 unsigned char md_value[EVP_MAX_MD_SIZE];
533 unsigned int md_len, i;
535 if (argv[1] == NULL) {
536 printf("Usage: mdtest digestname\n");
540 md = EVP_get_digestbyname(argv[1]);
542 printf("Unknown message digest %s\n", argv[1]);
546 mdctx = EVP_MD_CTX_new();
547 EVP_DigestInit_ex(mdctx, md, NULL);
548 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
549 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
550 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
551 EVP_MD_CTX_free(mdctx);
553 printf("Digest is: ");
554 for (i = 0; i < md_len; i++)
555 printf("%02x", md_value[i]);
563 L<EVP_MD_meth_new(3)>,
569 The full list of digest algorithms are provided below.
571 L<EVP_blake2b512(3)>,
582 L<provider(7)/Fetching algorithms>
586 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
587 EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
589 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
590 later, so now EVP_sha1() can be used with RSA and DSA.
592 The EVP_dss1() function was removed in OpenSSL 1.1.0.
594 The EVP_MD_CTX_set_pkey_ctx() function was added in 1.1.1.
596 The EVP_MD_fetch(), EVP_MD_free(), EVP_MD_up_ref(), EVP_MD_CTX_set_params()
597 and EVP_MD_CTX_get_params() functions were added in 3.0.
601 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
603 Licensed under the Apache License 2.0 (the "License"). You may not use
604 this file except in compliance with the License. You can obtain a copy
605 in the file LICENSE in the source distribution or at
606 L<https://www.openssl.org/source/license.html>.