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_settable_ctx_params, EVP_MD_gettable_ctx_params,
11 EVP_MD_CTX_settable_params, EVP_MD_CTX_gettable_params,
12 EVP_MD_CTX_set_flags, EVP_MD_CTX_clear_flags, EVP_MD_CTX_test_flags,
13 EVP_Digest, EVP_DigestInit_ex, EVP_DigestInit, EVP_DigestUpdate,
14 EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
15 EVP_MD_is_a, EVP_MD_name, EVP_MD_number, EVP_MD_names_do_all, EVP_MD_provider,
16 EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_flags,
18 EVP_MD_CTX_md, EVP_MD_CTX_type, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
19 EVP_MD_CTX_md_data, EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn,
21 EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
22 EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_set_pkey_ctx,
23 EVP_MD_do_all_provided
28 #include <openssl/evp.h>
30 EVP_MD *EVP_MD_fetch(OPENSSL_CTX *ctx, const char *algorithm,
31 const char *properties);
32 int EVP_MD_up_ref(EVP_MD *md);
33 void EVP_MD_free(EVP_MD *md);
34 int EVP_MD_get_params(const EVP_MD *digest, OSSL_PARAM params[]);
35 const OSSL_PARAM *EVP_MD_gettable_params(const EVP_MD *digest);
36 EVP_MD_CTX *EVP_MD_CTX_new(void);
37 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
38 void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
39 void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
40 int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
41 int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
42 const OSSL_PARAM *EVP_MD_settable_ctx_params(const EVP_MD *md);
43 const OSSL_PARAM *EVP_MD_gettable_ctx_params(const EVP_MD *md);
44 const OSSL_PARAM *EVP_MD_CTX_settable_params(EVP_MD_CTX *ctx);
45 const OSSL_PARAM *EVP_MD_CTX_gettable_params(EVP_MD_CTX *ctx);
46 void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
47 void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
48 int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
50 int EVP_Digest(const void *data, size_t count, unsigned char *md,
51 unsigned int *size, const EVP_MD *type, ENGINE *impl);
52 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
53 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
54 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
55 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
57 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
59 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
60 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
62 int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
64 const char *EVP_MD_name(const EVP_MD *md);
65 int EVP_MD_number(const EVP_MD *md);
66 int EVP_MD_is_a(const EVP_MD *md, const char *name);
67 void EVP_MD_names_do_all(const EVP_MD *md,
68 void (*fn)(const char *name, void *data),
70 const OSSL_PROVIDER *EVP_MD_provider(const EVP_MD *md);
71 int EVP_MD_type(const EVP_MD *md);
72 int EVP_MD_pkey_type(const EVP_MD *md);
73 int EVP_MD_size(const EVP_MD *md);
74 int EVP_MD_block_size(const EVP_MD *md);
75 unsigned long EVP_MD_flags(const EVP_MD *md);
77 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
78 const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
79 int EVP_MD_CTX_size(const EVP_MD_CTX *ctx);
80 int EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);
81 int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);
82 void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
83 int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
84 const void *data, size_t count);
85 void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
86 int (*update)(EVP_MD_CTX *ctx,
87 const void *data, size_t count));
89 const EVP_MD *EVP_md_null(void);
91 const EVP_MD *EVP_get_digestbyname(const char *name);
92 const EVP_MD *EVP_get_digestbynid(int type);
93 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
95 EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);
96 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
98 void EVP_MD_do_all_provided(OPENSSL_CTX *libctx,
99 void (*fn)(EVP_MD *mac, void *arg),
104 The EVP digest routines are a high level interface to message digests,
105 and should be used instead of the digest-specific functions.
107 The B<EVP_MD> type is a structure for digest method implementation.
113 Fetches the digest implementation for the given B<algorithm> from any
114 provider offering it, within the criteria given by the B<properties>.
115 See L<provider(7)/Fetching algorithms> for further information.
117 The returned value must eventually be freed with EVP_MD_free().
119 Fetched B<EVP_MD> structures are reference counted.
121 =item EVP_MD_up_ref()
123 Increments the reference count for an B<EVP_MD> structure.
127 Decrements the reference count for the fetched B<EVP_MD> structure.
128 If the reference count drops to 0 then the structure is freed.
130 =item EVP_MD_CTX_new()
132 Allocates and returns a digest context.
134 =item EVP_MD_CTX_reset()
136 Resets the digest context B<ctx>. This can be used to reuse an already
139 =item EVP_MD_CTX_free()
141 Cleans up digest context B<ctx> and frees up the space allocated to it.
143 =item EVP_MD_CTX_ctrl()
145 This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
146 is the mechanism that should be used to set and get parameters that are used by
148 Performs digest-specific control actions on context B<ctx>. The control command
149 is indicated in B<cmd> and any additional arguments in B<p1> and B<p2>.
150 EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex(). Other restrictions
151 may apply depending on the control type and digest implementation.
152 See L</CONTROLS> below for more information.
154 =item EVP_MD_get_params()
156 Retrieves the requested list of B<params> from a MD B<md>.
157 See L</PARAMETERS> below for more information.
159 =item EVP_MD_CTX_get_params()
161 Retrieves the requested list of B<params> from a MD context B<ctx>.
162 See L</PARAMETERS> below for more information.
164 =item EVP_MD_CTX_set_params()
166 Sets the list of B<params> into a MD context B<ctx>.
167 See L</PARAMETERS> below for more information.
169 =item EVP_MD_gettable_params(), EVP_MD_gettable_ctx_params(),
170 EVP_MD_settable_ctx_params(), EVP_MD_CTX_gettable_params(),
171 EVP_MD_CTX_settable_params()
173 Get a B<OSSL_PARAM> array that describes the retrievable and settable
174 parameters. EVP_MD_gettable_params() returns parameters that can be used with
175 EVP_MD_get_params(). EVP_MD_gettable_ctx_params() and
176 EVP_MD_CTX_gettable_params() return parameters that can be used with
177 EVP_MD_CTX_get_params(). EVP_MD_settable_ctx_params() and
178 EVP_MD_CTX_settable_params() return parameters that can be used with
179 EVP_MD_CTX_set_params().
180 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
182 =item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
184 Sets, clears and tests B<ctx> flags. See L</FLAGS> below for more information.
188 A wrapper around the Digest Init_ex, Update and Final_ex functions.
189 Hashes B<count> bytes of data at B<data> using a digest B<type> from ENGINE
190 B<impl>. The digest value is placed in B<md> and its length is written at B<size>
191 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
192 If B<impl> is NULL the default implementation of digest B<type> is used.
194 =item EVP_DigestInit_ex()
196 Sets up digest context B<ctx> to use a digest B<type>.
197 B<type> is typically supplied by a function such as EVP_sha1(), or a
198 value explicitly fetched with EVP_MD_fetch().
200 If B<impl> is non-NULL, its implementation of the digest B<type> is used if
201 there is one, and if not, the default implementation is used.
203 =item EVP_DigestUpdate()
205 Hashes B<cnt> bytes of data at B<d> into the digest context B<ctx>. This
206 function can be called several times on the same B<ctx> to hash additional
209 =item EVP_DigestFinal_ex()
211 Retrieves the digest value from B<ctx> and places it in B<md>. If the B<s>
212 parameter is not NULL then the number of bytes of data written (i.e. the
213 length of the digest) will be written to the integer at B<s>, at most
214 B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
215 no additional calls to EVP_DigestUpdate() can be made, but
216 EVP_DigestInit_ex() can be called to initialize a new digest operation.
218 =item EVP_DigestFinalXOF()
220 Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
221 It retrieves the digest value from B<ctx> and places it in B<len>-sized <B>md.
222 After calling this function no additional calls to EVP_DigestUpdate() can be
223 made, but EVP_DigestInit_ex() can be called to initialize a new operation.
225 =item EVP_MD_CTX_copy_ex()
227 Can be used to copy the message digest state from B<in> to B<out>. This is
228 useful if large amounts of data are to be hashed which only differ in the last
231 =item EVP_DigestInit()
233 Behaves in the same way as EVP_DigestInit_ex() except it always uses the
234 default digest implementation and calls EVP_MD_CTX_reset().
236 =item EVP_DigestFinal()
238 Similar to EVP_DigestFinal_ex() except the digest context B<ctx> is
239 automatically cleaned up.
241 =item EVP_MD_CTX_copy()
243 Similar to EVP_MD_CTX_copy_ex() except the destination B<out> does not have to
248 Returns 1 if I<md> is an implementation of an algorithm that's
249 identifiable with I<name>, otherwise 0.
251 If I<md> is a legacy digest (it's the return value from the likes of
252 EVP_sha256() rather than the result of an EVP_MD_fetch()), only cipher
253 names registered with the default library context (see
254 L<OPENSSL_CTX(3)>) will be considered.
256 =item EVP_MD_number()
258 Returns the internal dynamic number assigned to the I<md>. This is
259 only useful with fetched B<EVP_MD>s.
264 Return the name of the given message digest. For fetched message
265 digests with multiple names, only one of them is returned; it's
266 recommended to use EVP_MD_names_do_all() instead.
268 =item EVP_MD_names_do_all()
270 Traverses all names for the I<md>, and calls I<fn> with each name and
271 I<data>. This is only useful with fetched B<EVP_MD>s.
273 =item EVP_MD_provider()
275 Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given
281 Return the size of the message digest when passed an B<EVP_MD> or an
282 B<EVP_MD_CTX> structure, i.e. the size of the hash.
284 =item EVP_MD_block_size(),
285 EVP_MD_CTX_block_size()
287 Return the block size of the message digest when passed an B<EVP_MD> or an
288 B<EVP_MD_CTX> structure.
293 Return the NID of the OBJECT IDENTIFIER representing the given message digest
294 when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
295 returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
297 =item EVP_MD_CTX_md_data()
299 Return the digest method private data for the passed B<EVP_MD_CTX>.
300 The space is allocated by OpenSSL and has the size originally set with
301 EVP_MD_meth_set_app_datasize().
303 =item EVP_MD_CTX_md()
305 Returns the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
306 will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex() (or
307 other similar function) when the EVP_MD_CTX was first initialised. Note that
308 where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
309 this function will not have its reference count incremented and therefore it
310 should not be used after the EVP_MD_CTX is freed.
312 =item EVP_MD_CTX_set_update_fn()
314 Sets the update function for B<ctx> to B<update>.
315 This is the function that is called by EVP_DigestUpdate. If not set, the
316 update function from the B<EVP_MD> type specified at initialization is used.
318 =item EVP_MD_CTX_update_fn()
320 Returns the update function for B<ctx>.
324 Returns the B<md> flags. Note that these are different from the B<EVP_MD_CTX>
325 ones. See L<EVP_MD_meth_set_flags(3)> for more information.
327 =item EVP_MD_pkey_type()
329 Returns the NID of the public key signing algorithm associated with this
330 digest. For example EVP_sha1() is associated with RSA so this will return
331 B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
332 longer linked this function is only retained for compatibility reasons.
336 A "null" message digest that does nothing: i.e. the hash it returns is of zero
339 =item EVP_get_digestbyname(),
340 EVP_get_digestbynid(),
341 EVP_get_digestbyobj()
343 Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
344 B<ASN1_OBJECT> structure respectively.
346 =item EVP_MD_CTX_pkey_ctx()
348 Returns the B<EVP_PKEY_CTX> assigned to B<ctx>. The returned pointer should not
349 be freed by the caller.
351 =item EVP_MD_CTX_set_pkey_ctx()
353 Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
354 a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
355 L<EVP_DigestVerifyInit(3)>. The B<pctx> passed to this function should be freed
356 by the caller. A NULL B<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
357 assigned to B<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
358 depends on how the B<EVP_PKEY_CTX> is created.
360 =item EVP_MD_do_all_provided()
362 Traverses all messages digests implemented by all activated providers
363 in the given library context I<libctx>, and for each of the implementations,
364 calls the given function I<fn> with the implementation method and the given
371 See L<OSSL_PARAM(3)> for information about passing parameters.
373 EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
377 =item "xoflen" (B<OSSL_PARAM_DIGEST_KEY_XOFLEN>) <unsigned integer>
379 Sets the digest length for extendable output functions.
380 It is used by the SHAKE algorithm and should not exceed what can be given
383 =item "pad_type" (B<OSSL_PARAM_DIGEST_KEY_PAD_TYPE>) <integer>
386 It is used by the MDC2 algorithm.
390 EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
394 =item "micalg" (B<OSSL_PARAM_DIGEST_KEY_MICALG>) <UTF8 string>.
396 Gets the digest Message Integrity Check algorithm string. This is used when
397 creating S/MIME multipart/signed messages, as specified in RFC 3851.
398 It may be used by external engines or providers.
404 EVP_MD_CTX_ctrl() can be used to send the following standard controls:
408 =item EVP_MD_CTRL_MICALG
410 Gets the digest Message Integrity Check algorithm string. This is used when
411 creating S/MIME multipart/signed messages, as specified in RFC 3851.
412 The string value is written to B<p2>.
414 =item EVP_MD_CTRL_XOF_LEN
416 This control sets the digest length for extendable output functions to B<p1>.
417 Sending this control directly should not be necessary, the use of
418 C<EVP_DigestFinalXOF()> is preferred.
419 Currently used by SHAKE.
425 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
426 can be used the manipulate and test these B<EVP_MD_CTX> flags:
430 =item EVP_MD_CTX_FLAG_ONESHOT
432 This flag instructs the digest to optimize for one update only, if possible.
434 =for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
436 =for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
438 =for comment We currently avoid documenting flags that are only bit holder:
439 EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
441 =item EVP_MD_CTX_FLAG_NO_INIT
443 This flag instructs EVP_DigestInit() and similar not to initialise the
444 implementation specific data.
446 =item EVP_MD_CTX_FLAG_FINALISE
448 Some functions such as EVP_DigestSign only finalise copies of internal
449 contexts so additional data can be included after the finalisation call.
450 This is inefficient if this functionality is not required, and can be
451 disabled with this flag.
461 Returns a pointer to a B<EVP_MD> for success or NULL for failure.
463 =item EVP_MD_up_ref()
465 Returns 1 for success or 0 for failure.
467 =item EVP_DigestInit_ex(),
472 success and 0 for failure.
474 =item EVP_MD_CTX_ctrl()
476 Returns 1 if successful or 0 for failure.
478 =item EVP_MD_CTX_set_params(),
479 EVP_MD_CTX_get_params()
481 Returns 1 if successful or 0 for failure.
483 =item EVP_MD_CTX_settable_params(),
484 EVP_MD_CTX_gettable_params()
486 Return an array of constant B<OSSL_PARAM>s, or NULL if there is none
489 =item EVP_MD_CTX_copy_ex()
491 Returns 1 if successful or 0 for failure.
496 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
502 EVP_MD_CTX_block_size()
504 Returns the digest or block size in bytes.
508 Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
510 =item EVP_get_digestbyname(),
511 EVP_get_digestbynid(),
512 EVP_get_digestbyobj()
514 Returns either an B<EVP_MD> structure or NULL if an error occurs.
516 =item EVP_MD_CTX_set_pkey_ctx()
518 This function has no return value.
524 The B<EVP> interface to message digests should almost always be used in
525 preference to the low level interfaces. This is because the code then becomes
526 transparent to the digest used and much more flexible.
528 New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
529 digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
530 are still in common use.
532 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
533 set to NULL to use the default digest implementation.
535 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
536 obsolete but are retained to maintain compatibility with existing code. New
537 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
538 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
539 instead of initializing and cleaning it up on each call and allow non default
540 implementations of digests to be specified.
542 If digest contexts are not cleaned up after use,
543 memory leaks will occur.
545 EVP_MD_CTX_name(), EVP_MD_CTX_size(), EVP_MD_CTX_block_size(),
546 EVP_MD_CTX_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are defined
549 EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
554 This example digests the data "Test Message\n" and "Hello World\n", using the
555 digest name passed on the command line.
559 #include <openssl/evp.h>
561 int main(int argc, char *argv[])
565 char mess1[] = "Test Message\n";
566 char mess2[] = "Hello World\n";
567 unsigned char md_value[EVP_MAX_MD_SIZE];
568 unsigned int md_len, i;
570 if (argv[1] == NULL) {
571 printf("Usage: mdtest digestname\n");
575 md = EVP_get_digestbyname(argv[1]);
577 printf("Unknown message digest %s\n", argv[1]);
581 mdctx = EVP_MD_CTX_new();
582 EVP_DigestInit_ex(mdctx, md, NULL);
583 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
584 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
585 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
586 EVP_MD_CTX_free(mdctx);
588 printf("Digest is: ");
589 for (i = 0; i < md_len; i++)
590 printf("%02x", md_value[i]);
598 L<EVP_MD_meth_new(3)>,
604 The full list of digest algorithms are provided below.
606 L<EVP_blake2b512(3)>,
617 L<provider(7)/Fetching algorithms>
621 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
622 EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
624 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
625 later, so now EVP_sha1() can be used with RSA and DSA.
627 The EVP_dss1() function was removed in OpenSSL 1.1.0.
629 The EVP_MD_CTX_set_pkey_ctx() function was added in 1.1.1.
631 The EVP_MD_fetch(), EVP_MD_free(), EVP_MD_up_ref(), EVP_MD_CTX_set_params()
632 and EVP_MD_CTX_get_params() functions were added in 3.0.
636 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
638 Licensed under the Apache License 2.0 (the "License"). You may not use
639 this file except in compliance with the License. You can obtain a copy
640 in the file LICENSE in the source distribution or at
641 L<https://www.openssl.org/source/license.html>.