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_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_is_a(const EVP_MD *md, const char *name);
66 void EVP_MD_names_do_all(const EVP_MD *md,
67 void (*fn)(const char *name, void *data),
69 const OSSL_PROVIDER *EVP_MD_provider(const EVP_MD *md);
70 int EVP_MD_type(const EVP_MD *md);
71 int EVP_MD_pkey_type(const EVP_MD *md);
72 int EVP_MD_size(const EVP_MD *md);
73 int EVP_MD_block_size(const EVP_MD *md);
74 unsigned long EVP_MD_flags(const EVP_MD *md);
76 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
77 const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
78 int EVP_MD_CTX_size(const EVP_MD_CTX *ctx);
79 int EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);
80 int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);
81 void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
82 int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
83 const void *data, size_t count);
84 void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
85 int (*update)(EVP_MD_CTX *ctx,
86 const void *data, size_t count));
88 const EVP_MD *EVP_md_null(void);
90 const EVP_MD *EVP_get_digestbyname(const char *name);
91 const EVP_MD *EVP_get_digestbynid(int type);
92 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
94 EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);
95 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
97 void EVP_MD_do_all_provided(OPENSSL_CTX *libctx,
98 void (*fn)(EVP_MD *mac, void *arg),
103 The EVP digest routines are a high level interface to message digests,
104 and should be used instead of the digest-specific functions.
106 The B<EVP_MD> type is a structure for digest method implementation.
112 Fetches the digest implementation for the given B<algorithm> from any
113 provider offering it, within the criteria given by the B<properties>.
114 See L<provider(7)/Fetching algorithms> for further information.
116 The returned value must eventually be freed with EVP_MD_free().
118 Fetched B<EVP_MD> structures are reference counted.
120 =item EVP_MD_up_ref()
122 Increments the reference count for an B<EVP_MD> structure.
126 Decrements the reference count for the fetched B<EVP_MD> structure.
127 If the reference count drops to 0 then the structure is freed.
129 =item EVP_MD_CTX_new()
131 Allocates and returns a digest context.
133 =item EVP_MD_CTX_reset()
135 Resets the digest context B<ctx>. This can be used to reuse an already
138 =item EVP_MD_CTX_free()
140 Cleans up digest context B<ctx> and frees up the space allocated to it.
142 =item EVP_MD_CTX_ctrl()
144 This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
145 is the mechanism that should be used to set and get parameters that are used by
147 Performs digest-specific control actions on context B<ctx>. The control command
148 is indicated in B<cmd> and any additional arguments in B<p1> and B<p2>.
149 EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex(). Other restrictions
150 may apply depending on the control type and digest implementation.
151 See L</CONTROLS> below for more information.
153 =item EVP_MD_get_params()
155 Retrieves the requested list of B<params> from a MD B<md>.
156 See L</PARAMETERS> below for more information.
158 =item EVP_MD_CTX_get_params()
160 Retrieves the requested list of B<params> from a MD context B<ctx>.
161 See L</PARAMETERS> below for more information.
163 =item EVP_MD_CTX_set_params()
165 Sets the list of B<params> into a MD context B<ctx>.
166 See L</PARAMETERS> below for more information.
168 =item EVP_MD_gettable_params(), EVP_MD_gettable_ctx_params(),
169 EVP_MD_settable_ctx_params(), EVP_MD_CTX_gettable_params(),
170 EVP_MD_CTX_settable_params()
172 Get a B<OSSL_PARAM> array that describes the retrievable and settable
173 parameters. EVP_MD_gettable_params() returns parameters that can be used with
174 EVP_MD_get_params(). EVP_MD_gettable_ctx_params() and
175 EVP_MD_CTX_gettable_params() return parameters that can be used with
176 EVP_MD_CTX_get_params(). EVP_MD_settable_ctx_params() and
177 EVP_MD_CTX_settable_params() return parameters that can be used with
178 EVP_MD_CTX_set_params().
179 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
181 =item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
183 Sets, clears and tests B<ctx> flags. See L</FLAGS> below for more information.
187 A wrapper around the Digest Init_ex, Update and Final_ex functions.
188 Hashes B<count> bytes of data at B<data> using a digest B<type> from ENGINE
189 B<impl>. The digest value is placed in B<md> and its length is written at B<size>
190 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
191 If B<impl> is NULL the default implementation of digest B<type> is used.
193 =item EVP_DigestInit_ex()
195 Sets up digest context B<ctx> to use a digest B<type>.
196 B<type> is typically supplied by a function such as EVP_sha1(), or a
197 value explicitly fetched with EVP_MD_fetch().
199 If B<impl> is non-NULL, its implementation of the digest B<type> is used if
200 there is one, and if not, the default implementation is used.
202 =item EVP_DigestUpdate()
204 Hashes B<cnt> bytes of data at B<d> into the digest context B<ctx>. This
205 function can be called several times on the same B<ctx> to hash additional
208 =item EVP_DigestFinal_ex()
210 Retrieves the digest value from B<ctx> and places it in B<md>. If the B<s>
211 parameter is not NULL then the number of bytes of data written (i.e. the
212 length of the digest) will be written to the integer at B<s>, at most
213 B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
214 no additional calls to EVP_DigestUpdate() can be made, but
215 EVP_DigestInit_ex() can be called to initialize a new digest operation.
217 =item EVP_DigestFinalXOF()
219 Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
220 It retrieves the digest value from B<ctx> and places it in B<len>-sized <B>md.
221 After calling this function no additional calls to EVP_DigestUpdate() can be
222 made, but EVP_DigestInit_ex() can be called to initialize a new operation.
224 =item EVP_MD_CTX_copy_ex()
226 Can be used to copy the message digest state from B<in> to B<out>. This is
227 useful if large amounts of data are to be hashed which only differ in the last
230 =item EVP_DigestInit()
232 Behaves in the same way as EVP_DigestInit_ex() except it always uses the
233 default digest implementation and calls EVP_MD_CTX_reset().
235 =item EVP_DigestFinal()
237 Similar to EVP_DigestFinal_ex() except the digest context B<ctx> is
238 automatically cleaned up.
240 =item EVP_MD_CTX_copy()
242 Similar to EVP_MD_CTX_copy_ex() except the destination B<out> does not have to
247 Returns 1 if I<md> is an implementation of an algorithm that's
248 identifiable with I<name>, otherwise 0.
253 Return the name of the given message digest. For fetched message
254 digests with multiple names, only one of them is returned; it's
255 recommended to use EVP_MD_names_do_all() instead.
257 =item EVP_MD_names_do_all()
259 Traverses all names for the I<md>, and calls I<fn> with each name and
260 I<data>. This is only useful with fetched B<EVP_MD>s.
262 =item EVP_MD_provider()
264 Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given
270 Return the size of the message digest when passed an B<EVP_MD> or an
271 B<EVP_MD_CTX> structure, i.e. the size of the hash.
273 =item EVP_MD_block_size(),
274 EVP_MD_CTX_block_size()
276 Return the block size of the message digest when passed an B<EVP_MD> or an
277 B<EVP_MD_CTX> structure.
282 Return the NID of the OBJECT IDENTIFIER representing the given message digest
283 when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
284 returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
286 =item EVP_MD_CTX_md_data()
288 Return the digest method private data for the passed B<EVP_MD_CTX>.
289 The space is allocated by OpenSSL and has the size originally set with
290 EVP_MD_meth_set_app_datasize().
292 =item EVP_MD_CTX_md()
294 Returns the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
295 will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex() (or
296 other similar function) when the EVP_MD_CTX was first initialised. Note that
297 where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
298 this function will not have its reference count incremented and therefore it
299 should not be used after the EVP_MD_CTX is freed.
301 =item EVP_MD_CTX_set_update_fn()
303 Sets the update function for B<ctx> to B<update>.
304 This is the function that is called by EVP_DigestUpdate. If not set, the
305 update function from the B<EVP_MD> type specified at initialization is used.
307 =item EVP_MD_CTX_update_fn()
309 Returns the update function for B<ctx>.
313 Returns the B<md> flags. Note that these are different from the B<EVP_MD_CTX>
314 ones. See L<EVP_MD_meth_set_flags(3)> for more information.
316 =item EVP_MD_pkey_type()
318 Returns the NID of the public key signing algorithm associated with this
319 digest. For example EVP_sha1() is associated with RSA so this will return
320 B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
321 longer linked this function is only retained for compatibility reasons.
325 A "null" message digest that does nothing: i.e. the hash it returns is of zero
328 =item EVP_get_digestbyname(),
329 EVP_get_digestbynid(),
330 EVP_get_digestbyobj()
332 Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
333 B<ASN1_OBJECT> structure respectively.
335 =item EVP_MD_CTX_pkey_ctx()
337 Returns the B<EVP_PKEY_CTX> assigned to B<ctx>. The returned pointer should not
338 be freed by the caller.
340 =item EVP_MD_CTX_set_pkey_ctx()
342 Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
343 a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
344 L<EVP_DigestVerifyInit(3)>. The B<pctx> passed to this function should be freed
345 by the caller. A NULL B<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
346 assigned to B<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
347 depends on how the B<EVP_PKEY_CTX> is created.
349 =item EVP_MD_do_all_provided()
351 Traverses all messages digests implemented by all activated providers
352 in the given library context I<libctx>, and for each of the implementations,
353 calls the given function I<fn> with the implementation method and the given
360 See L<OSSL_PARAM(3)> for information about passing parameters.
362 EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
366 =item "xoflen" (B<OSSL_PARAM_DIGEST_KEY_XOFLEN>) <unsigned integer>
368 Sets the digest length for extendable output functions.
369 It is used by the SHAKE algorithm and should not exceed what can be given
372 =item "pad_type" (B<OSSL_PARAM_DIGEST_KEY_PAD_TYPE>) <integer>
375 It is used by the MDC2 algorithm.
379 EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
383 =item "micalg" (B<OSSL_PARAM_DIGEST_KEY_MICALG>) <UTF8 string>.
385 Gets the digest Message Integrity Check algorithm string. This is used when
386 creating S/MIME multipart/signed messages, as specified in RFC 3851.
387 It may be used by external engines or providers.
393 EVP_MD_CTX_ctrl() can be used to send the following standard controls:
397 =item EVP_MD_CTRL_MICALG
399 Gets the digest Message Integrity Check algorithm string. This is used when
400 creating S/MIME multipart/signed messages, as specified in RFC 3851.
401 The string value is written to B<p2>.
403 =item EVP_MD_CTRL_XOF_LEN
405 This control sets the digest length for extendable output functions to B<p1>.
406 Sending this control directly should not be necessary, the use of
407 C<EVP_DigestFinalXOF()> is preferred.
408 Currently used by SHAKE.
414 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
415 can be used the manipulate and test these B<EVP_MD_CTX> flags:
419 =item EVP_MD_CTX_FLAG_ONESHOT
421 This flag instructs the digest to optimize for one update only, if possible.
423 =for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
425 =for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
427 =for comment We currently avoid documenting flags that are only bit holder:
428 EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
430 =item EVP_MD_CTX_FLAG_NO_INIT
432 This flag instructs EVP_DigestInit() and similar not to initialise the
433 implementation specific data.
435 =item EVP_MD_CTX_FLAG_FINALISE
437 Some functions such as EVP_DigestSign only finalise copies of internal
438 contexts so additional data can be included after the finalisation call.
439 This is inefficient if this functionality is not required, and can be
440 disabled with this flag.
450 Returns a pointer to a B<EVP_MD> for success or NULL for failure.
452 =item EVP_MD_up_ref()
454 Returns 1 for success or 0 for failure.
456 =item EVP_DigestInit_ex(),
461 success and 0 for failure.
463 =item EVP_MD_CTX_ctrl()
465 Returns 1 if successful or 0 for failure.
467 =item EVP_MD_CTX_set_params(),
468 EVP_MD_CTX_get_params()
470 Returns 1 if successful or 0 for failure.
472 =item EVP_MD_CTX_settable_params(),
473 EVP_MD_CTX_gettable_params()
475 Return an array of constant B<OSSL_PARAM>s, or NULL if there is none
478 =item EVP_MD_CTX_copy_ex()
480 Returns 1 if successful or 0 for failure.
485 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
491 EVP_MD_CTX_block_size()
493 Returns the digest or block size in bytes.
497 Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
499 =item EVP_get_digestbyname(),
500 EVP_get_digestbynid(),
501 EVP_get_digestbyobj()
503 Returns either an B<EVP_MD> structure or NULL if an error occurs.
505 =item EVP_MD_CTX_set_pkey_ctx()
507 This function has no return value.
513 The B<EVP> interface to message digests should almost always be used in
514 preference to the low level interfaces. This is because the code then becomes
515 transparent to the digest used and much more flexible.
517 New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
518 digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
519 are still in common use.
521 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
522 set to NULL to use the default digest implementation.
524 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
525 obsolete but are retained to maintain compatibility with existing code. New
526 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
527 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
528 instead of initializing and cleaning it up on each call and allow non default
529 implementations of digests to be specified.
531 If digest contexts are not cleaned up after use,
532 memory leaks will occur.
534 EVP_MD_CTX_name(), EVP_MD_CTX_size(), EVP_MD_CTX_block_size(),
535 EVP_MD_CTX_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are defined
538 EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
543 This example digests the data "Test Message\n" and "Hello World\n", using the
544 digest name passed on the command line.
548 #include <openssl/evp.h>
550 int main(int argc, char *argv[])
554 char mess1[] = "Test Message\n";
555 char mess2[] = "Hello World\n";
556 unsigned char md_value[EVP_MAX_MD_SIZE];
557 unsigned int md_len, i;
559 if (argv[1] == NULL) {
560 printf("Usage: mdtest digestname\n");
564 md = EVP_get_digestbyname(argv[1]);
566 printf("Unknown message digest %s\n", argv[1]);
570 mdctx = EVP_MD_CTX_new();
571 EVP_DigestInit_ex(mdctx, md, NULL);
572 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
573 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
574 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
575 EVP_MD_CTX_free(mdctx);
577 printf("Digest is: ");
578 for (i = 0; i < md_len; i++)
579 printf("%02x", md_value[i]);
587 L<EVP_MD_meth_new(3)>,
593 The full list of digest algorithms are provided below.
595 L<EVP_blake2b512(3)>,
606 L<provider(7)/Fetching algorithms>
610 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
611 EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
613 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
614 later, so now EVP_sha1() can be used with RSA and DSA.
616 The EVP_dss1() function was removed in OpenSSL 1.1.0.
618 The EVP_MD_CTX_set_pkey_ctx() function was added in 1.1.1.
620 The EVP_MD_fetch(), EVP_MD_free(), EVP_MD_up_ref(), EVP_MD_CTX_set_params()
621 and EVP_MD_CTX_get_params() functions were added in 3.0.
625 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
627 Licensed under the Apache License 2.0 (the "License"). You may not use
628 this file except in compliance with the License. You can obtain a copy
629 in the file LICENSE in the source distribution or at
630 L<https://www.openssl.org/source/license.html>.