6 EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy,
7 EVP_MD_CTX_copy_ex, EVP_MD_CTX_ctrl, EVP_MD_CTX_set_params, EVP_MD_CTX_get_params,
8 EVP_MD_CTX_set_flags, EVP_MD_CTX_clear_flags, EVP_MD_CTX_test_flags,
9 EVP_Digest, EVP_DigestInit_ex, EVP_DigestInit, EVP_DigestUpdate,
10 EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
12 EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_flags,
14 EVP_MD_CTX_md, EVP_MD_CTX_type, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
15 EVP_MD_CTX_md_data, EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn,
17 EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
18 EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_set_pkey_ctx - EVP digest routines
22 #include <openssl/evp.h>
24 EVP_MD *EVP_MD_fetch(OPENSSL_CTX *ctx, const char *algorithm,
25 const char *properties);
26 EVP_MD_CTX *EVP_MD_CTX_new(void);
27 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
28 void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
29 void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
30 int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
31 int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
32 void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
33 void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
34 int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
36 int EVP_Digest(const void *data, size_t count, unsigned char *md,
37 unsigned int *size, const EVP_MD *type, ENGINE *impl);
38 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
39 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
40 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
41 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
43 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
45 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
46 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
48 int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
50 const char *EVP_MD_name(const EVP_MD *md);
51 int EVP_MD_type(const EVP_MD *md);
52 int EVP_MD_pkey_type(const EVP_MD *md);
53 int EVP_MD_size(const EVP_MD *md);
54 int EVP_MD_block_size(const EVP_MD *md);
55 unsigned long EVP_MD_flags(const EVP_MD *md);
57 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
58 const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
59 int EVP_MD_CTX_size(const EVP_MD *ctx);
60 int EVP_MD_CTX_block_size(const EVP_MD *ctx);
61 int EVP_MD_CTX_type(const EVP_MD *ctx);
62 void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
63 int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
64 const void *data, size_t count);
65 void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
66 int (*update)(EVP_MD_CTX *ctx,
67 const void *data, size_t count));
69 const EVP_MD *EVP_md_null(void);
71 const EVP_MD *EVP_get_digestbyname(const char *name);
72 const EVP_MD *EVP_get_digestbynid(int type);
73 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
75 EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);
76 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
80 The EVP digest routines are a high level interface to message digests,
81 and should be used instead of the cipher-specific functions.
87 Fetches the digest implementation for the given B<algorithm> from any
88 provider offering it, within the criteria given by the B<properties>.
89 See L<provider(7)/Fetching algorithms> for further information.
91 The returned value must eventually be freed with L<EVP_MD_meth_free(3)>.
93 =item EVP_MD_CTX_new()
95 Allocates and returns a digest context.
97 =item EVP_MD_CTX_reset()
99 Resets the digest context B<ctx>. This can be used to reuse an already
102 =item EVP_MD_CTX_free()
104 Cleans up digest context B<ctx> and frees up the space allocated to it.
106 =item EVP_MD_CTX_ctrl()
108 This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
109 is the mechanism that should be used to set and get parameters that are used by
111 Performs digest-specific control actions on context B<ctx>. The control command
112 is indicated in B<cmd> and any additional arguments in B<p1> and B<p2>.
113 EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex(). Other restrictions
114 may apply depending on the control type and digest implementation.
115 See L</CONTROLS> below for more information.
117 =item EVP_MD_CTX_get_params
119 Retrieves the requested list of B<params> from a MD context B<ctx>.
120 See L</PARAMS> below for more information.
122 =item EVP_MD_CTX_set_params
124 Sets the list of <params> into a MD context B<ctx>.
125 See L</PARAMS> below for more information.
127 =item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
129 Sets, clears and tests B<ctx> flags. See L</FLAGS> below for more information.
133 A wrapper around the Digest Init_ex, Update and Final_ex functions.
134 Hashes B<count> bytes of data at B<data> using a digest B<type> from ENGINE
135 B<impl>. The digest value is placed in B<md> and its length is written at B<size>
136 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
137 If B<impl> is NULL the default implementation of digest B<type> is used.
139 =item EVP_DigestInit_ex()
141 Sets up digest context B<ctx> to use a digest B<type>.
142 B<type> is typically supplied by a function such as EVP_sha1(), or a
143 value explicitly fetched with EVP_MD_fetch().
145 If B<impl> is non-NULL, its implementation of the digest B<type> is used if
146 there is one, and if not, the default implementation is used.
148 =item EVP_DigestUpdate()
150 Hashes B<cnt> bytes of data at B<d> into the digest context B<ctx>. This
151 function can be called several times on the same B<ctx> to hash additional
154 =item EVP_DigestFinal_ex()
156 Retrieves the digest value from B<ctx> and places it in B<md>. If the B<s>
157 parameter is not NULL then the number of bytes of data written (i.e. the
158 length of the digest) will be written to the integer at B<s>, at most
159 B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
160 no additional calls to EVP_DigestUpdate() can be made, but
161 EVP_DigestInit_ex() can be called to initialize a new digest operation.
163 =item EVP_DigestFinalXOF()
165 Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
166 It retrieves the digest value from B<ctx> and places it in B<len>-sized <B>md.
167 After calling this function no additional calls to EVP_DigestUpdate() can be
168 made, but EVP_DigestInit_ex() can be called to initialize a new operation.
170 =item EVP_MD_CTX_copy_ex()
172 Can be used to copy the message digest state from B<in> to B<out>. This is
173 useful if large amounts of data are to be hashed which only differ in the last
176 =item EVP_DigestInit()
178 Behaves in the same way as EVP_DigestInit_ex() except it always uses the
179 default digest implementation.
181 =item EVP_DigestFinal()
183 Similar to EVP_DigestFinal_ex() except the digest context B<ctx> is
184 automatically cleaned up.
186 =item EVP_MD_CTX_copy()
188 Similar to EVP_MD_CTX_copy_ex() except the destination B<out> does not have to
194 Return the name of the given message digest.
199 Return the size of the message digest when passed an B<EVP_MD> or an
200 B<EVP_MD_CTX> structure, i.e. the size of the hash.
202 =item EVP_MD_block_size(),
203 EVP_MD_CTX_block_size()
205 Return the block size of the message digest when passed an B<EVP_MD> or an
206 B<EVP_MD_CTX> structure.
211 Return the NID of the OBJECT IDENTIFIER representing the given message digest
212 when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
213 returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
215 =item EVP_MD_CTX_md_data()
217 Return the digest method private data for the passed B<EVP_MD_CTX>.
218 The space is allocated by OpenSSL and has the size originally set with
219 EVP_MD_meth_set_app_datasize().
221 =item EVP_MD_CTX_md()
223 Returns the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
224 will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex() (or
225 other similar function) when the EVP_MD_CTX was first initialised. Note that
226 where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
227 this function will not have its reference count incremented and therefore it
228 should not be used after the EVP_MD_CTX is freed.
230 =item EVP_MD_CTX_set_update_fn()
232 Sets the update function for B<ctx> to B<update>.
233 This is the function that is called by EVP_DigestUpdate. If not set, the
234 update function from the B<EVP_MD> type specified at initialization is used.
236 =item EVP_MD_CTX_update_fn()
238 Returns the update function for B<ctx>.
242 Returns the B<md> flags. Note that these are different from the B<EVP_MD_CTX>
243 ones. See L<EVP_MD_meth_set_flags(3)> for more information.
245 =item EVP_MD_pkey_type()
247 Returns the NID of the public key signing algorithm associated with this
248 digest. For example EVP_sha1() is associated with RSA so this will return
249 B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
250 longer linked this function is only retained for compatibility reasons.
254 A "null" message digest that does nothing: i.e. the hash it returns is of zero
257 =item EVP_get_digestbyname(),
258 EVP_get_digestbynid(),
259 EVP_get_digestbyobj()
261 Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
262 B<ASN1_OBJECT> structure respectively.
264 =item EVP_MD_CTX_pkey_ctx()
266 Returns the B<EVP_PKEY_CTX> assigned to B<ctx>. The returned pointer should not
267 be freed by the caller.
269 =item EVP_MD_CTX_set_pkey_ctx()
271 Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
272 a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
273 L<EVP_DigestVerifyInit(3)>. The B<pctx> passed to this function should be freed
274 by the caller. A NULL B<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
275 assigned to B<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
276 depends on how the B<EVP_PKEY_CTX> is created.
282 See L<OSSL_PARAM(3)> for information about passing parameters.
284 EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
288 =item OSSL_PARAM_DIGEST_KEY_XOFLEN <size_t>
290 Sets the digest length for extendable output functions.
291 It is used by the SHAKE algorithm.
293 =item OSSL_PARAM_DIGEST_KEY_PAD_TYPE <int>
296 It is used by the MDC2 algorithm.
300 EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
304 =item OSSL_PARAM_DIGEST_KEY_MICALG <utf8string>.
306 Gets the digest Message Integrity Check algorithm string. This is used when
307 creating S/MIME multipart/signed messages, as specified in RFC 3851.
308 It may be used by external engines or providers.
314 EVP_MD_CTX_ctrl() can be used to send the following standard controls:
318 =item EVP_MD_CTRL_MICALG
320 Gets the digest Message Integrity Check algorithm string. This is used when
321 creating S/MIME multipart/signed messages, as specified in RFC 3851.
322 The string value is written to B<p2>.
324 =item EVP_MD_CTRL_XOF_LEN
326 This control sets the digest length for extendable output functions to B<p1>.
327 Sending this control directly should not be necessary, the use of
328 C<EVP_DigestFinalXOF()> is preferred.
329 Currently used by SHAKE.
335 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
336 can be used the manipulate and test these B<EVP_MD_CTX> flags:
340 =item EVP_MD_CTX_FLAG_ONESHOT
342 This flag instructs the digest to optimize for one update only, if possible.
344 =for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
346 =for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
348 =for comment We currently avoid documenting flags that are only bit holder:
349 EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
351 =item EVP_MD_CTX_FLAG_NO_INIT
353 This flag instructs EVP_DigestInit() and similar not to initialise the
354 implementation specific data.
356 =item EVP_MD_CTX_FLAG_FINALISE
358 Some functions such as EVP_DigestSign only finalise copies of internal
359 contexts so additional data can be included after the finalisation call.
360 This is inefficient if this functionality is not required, and can be
361 disabled with this flag.
371 Returns a pointer to a B<EVP_MD> for success or NULL for failure.
373 =item EVP_DigestInit_ex(),
378 success and 0 for failure.
380 =item EVP_MD_CTX_ctrl()
382 Returns 1 if successful or 0 for failure.
384 =item EVP_MD_CTX_set_params(),
385 EVP_MD_CTX_get_params()
387 Returns 1 if successful or 0 for failure.
389 =item EVP_MD_CTX_copy_ex()
391 Returns 1 if successful or 0 for failure.
396 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
402 EVP_MD_CTX_block_size()
404 Returns the digest or block size in bytes.
408 Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
410 =item EVP_get_digestbyname(),
411 EVP_get_digestbynid(),
412 EVP_get_digestbyobj()
414 Returns either an B<EVP_MD> structure or NULL if an error occurs.
416 =item EVP_MD_CTX_set_pkey_ctx()
418 This function has no return value.
424 The B<EVP> interface to message digests should almost always be used in
425 preference to the low level interfaces. This is because the code then becomes
426 transparent to the digest used and much more flexible.
428 New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
429 digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
430 are still in common use.
432 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
433 set to NULL to use the default digest implementation.
435 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
436 obsolete but are retained to maintain compatibility with existing code. New
437 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
438 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
439 instead of initializing and cleaning it up on each call and allow non default
440 implementations of digests to be specified.
442 If digest contexts are not cleaned up after use,
443 memory leaks will occur.
445 EVP_MD_CTX_name(), EVP_MD_CTX_size(), EVP_MD_CTX_block_size(),
446 EVP_MD_CTX_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are defined
449 EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
454 This example digests the data "Test Message\n" and "Hello World\n", using the
455 digest name passed on the command line.
459 #include <openssl/evp.h>
461 int main(int argc, char *argv[])
465 char mess1[] = "Test Message\n";
466 char mess2[] = "Hello World\n";
467 unsigned char md_value[EVP_MAX_MD_SIZE];
468 unsigned int md_len, i;
470 if (argv[1] == NULL) {
471 printf("Usage: mdtest digestname\n");
475 md = EVP_get_digestbyname(argv[1]);
477 printf("Unknown message digest %s\n", argv[1]);
481 mdctx = EVP_MD_CTX_new();
482 EVP_DigestInit_ex(mdctx, md, NULL);
483 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
484 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
485 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
486 EVP_MD_CTX_free(mdctx);
488 printf("Digest is: ");
489 for (i = 0; i < md_len; i++)
490 printf("%02x", md_value[i]);
498 L<EVP_MD_meth_new(3)>,
504 The full list of digest algorithms are provided below.
506 L<EVP_blake2b512(3)>,
517 L<provider(7)/Fetching algorithms>
521 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
522 EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
524 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
525 later, so now EVP_sha1() can be used with RSA and DSA.
527 The EVP_dss1() function was removed in OpenSSL 1.1.0.
529 The EVP_MD_CTX_set_pkey_ctx() function was added in 1.1.1.
531 The EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params() functions were
536 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
538 Licensed under the Apache License 2.0 (the "License"). You may not use
539 this file except in compliance with the License. You can obtain a copy
540 in the file LICENSE in the source distribution or at
541 L<https://www.openssl.org/source/license.html>.