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_dup,
8 EVP_MD_CTX_copy, 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_Q_digest, EVP_Digest, EVP_DigestInit_ex2, EVP_DigestInit_ex, EVP_DigestInit,
14 EVP_DigestUpdate, EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
16 EVP_MD_is_a, EVP_MD_get0_name, EVP_MD_get0_description,
17 EVP_MD_names_do_all, EVP_MD_get0_provider, EVP_MD_get_type,
18 EVP_MD_get_pkey_type, EVP_MD_get_size, EVP_MD_get_block_size, EVP_MD_get_flags,
19 EVP_MD_CTX_get0_name, EVP_MD_CTX_md, EVP_MD_CTX_get0_md, EVP_MD_CTX_get1_md,
20 EVP_MD_CTX_get_type, EVP_MD_CTX_get_size, EVP_MD_CTX_get_block_size,
21 EVP_MD_CTX_get0_md_data, EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn,
23 EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
24 EVP_MD_CTX_get_pkey_ctx, EVP_MD_CTX_set_pkey_ctx,
25 EVP_MD_do_all_provided,
26 EVP_MD_type, EVP_MD_nid, EVP_MD_name, EVP_MD_pkey_type, EVP_MD_size,
27 EVP_MD_block_size, EVP_MD_flags, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
28 EVP_MD_CTX_type, EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_md_data
33 #include <openssl/evp.h>
35 EVP_MD *EVP_MD_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
36 const char *properties);
37 int EVP_MD_up_ref(EVP_MD *md);
38 void EVP_MD_free(EVP_MD *md);
39 int EVP_MD_get_params(const EVP_MD *digest, OSSL_PARAM params[]);
40 const OSSL_PARAM *EVP_MD_gettable_params(const EVP_MD *digest);
41 EVP_MD_CTX *EVP_MD_CTX_new(void);
42 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
43 void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
44 void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
45 int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
46 int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
47 const OSSL_PARAM *EVP_MD_settable_ctx_params(const EVP_MD *md);
48 const OSSL_PARAM *EVP_MD_gettable_ctx_params(const EVP_MD *md);
49 const OSSL_PARAM *EVP_MD_CTX_settable_params(EVP_MD_CTX *ctx);
50 const OSSL_PARAM *EVP_MD_CTX_gettable_params(EVP_MD_CTX *ctx);
51 void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
52 void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
53 int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
55 int EVP_Q_digest(OSSL_LIB_CTX *libctx, const char *name, const char *propq,
56 const void *data, size_t datalen,
57 unsigned char *md, size_t *mdlen);
58 int EVP_Digest(const void *data, size_t count, unsigned char *md,
59 unsigned int *size, const EVP_MD *type, ENGINE *impl);
60 int EVP_DigestInit_ex2(EVP_MD_CTX *ctx, const EVP_MD *type,
61 const OSSL_PARAM params[]);
62 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
63 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
64 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
65 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *out, size_t outlen);
66 int EVP_DigestSqueeze(EVP_MD_CTX *ctx, unsigned char *out, size_t outlen);
68 EVP_MD_CTX *EVP_MD_CTX_dup(const EVP_MD_CTX *in);
69 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
71 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
72 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
74 int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
76 const char *EVP_MD_get0_name(const EVP_MD *md);
77 const char *EVP_MD_get0_description(const EVP_MD *md);
78 int EVP_MD_is_a(const EVP_MD *md, const char *name);
79 int EVP_MD_names_do_all(const EVP_MD *md,
80 void (*fn)(const char *name, void *data),
82 const OSSL_PROVIDER *EVP_MD_get0_provider(const EVP_MD *md);
83 int EVP_MD_get_type(const EVP_MD *md);
84 int EVP_MD_get_pkey_type(const EVP_MD *md);
85 int EVP_MD_get_size(const EVP_MD *md);
86 int EVP_MD_get_block_size(const EVP_MD *md);
87 unsigned long EVP_MD_get_flags(const EVP_MD *md);
89 const EVP_MD *EVP_MD_CTX_get0_md(const EVP_MD_CTX *ctx);
90 EVP_MD *EVP_MD_CTX_get1_md(EVP_MD_CTX *ctx);
91 const char *EVP_MD_CTX_get0_name(const EVP_MD_CTX *ctx);
92 int EVP_MD_CTX_get_size(const EVP_MD_CTX *ctx);
93 int EVP_MD_CTX_get_block_size(const EVP_MD_CTX *ctx);
94 int EVP_MD_CTX_get_type(const EVP_MD_CTX *ctx);
95 void *EVP_MD_CTX_get0_md_data(const EVP_MD_CTX *ctx);
97 const EVP_MD *EVP_md_null(void);
99 const EVP_MD *EVP_get_digestbyname(const char *name);
100 const EVP_MD *EVP_get_digestbynid(int type);
101 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
103 EVP_PKEY_CTX *EVP_MD_CTX_get_pkey_ctx(const EVP_MD_CTX *ctx);
104 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
106 void EVP_MD_do_all_provided(OSSL_LIB_CTX *libctx,
107 void (*fn)(EVP_MD *mac, void *arg),
110 #define EVP_MD_type EVP_MD_get_type
111 #define EVP_MD_nid EVP_MD_get_type
112 #define EVP_MD_name EVP_MD_get0_name
113 #define EVP_MD_pkey_type EVP_MD_get_pkey_type
114 #define EVP_MD_size EVP_MD_get_size
115 #define EVP_MD_block_size EVP_MD_get_block_size
116 #define EVP_MD_flags EVP_MD_get_flags
117 #define EVP_MD_CTX_size EVP_MD_CTX_get_size
118 #define EVP_MD_CTX_block_size EVP_MD_CTX_get_block_size
119 #define EVP_MD_CTX_type EVP_MD_CTX_get_type
120 #define EVP_MD_CTX_pkey_ctx EVP_MD_CTX_get_pkey_ctx
121 #define EVP_MD_CTX_md_data EVP_MD_CTX_get0_md_data
123 The following functions have been deprecated since OpenSSL 3.0, and can be
124 hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
125 see L<openssl_user_macros(7)>:
127 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
129 int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
130 const void *data, size_t count);
132 void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
133 int (*update)(EVP_MD_CTX *ctx,
134 const void *data, size_t count));
138 The EVP digest routines are a high-level interface to message digests,
139 and should be used instead of the digest-specific functions.
141 The B<EVP_MD> type is a structure for digest method implementation.
147 Fetches the digest implementation for the given I<algorithm> from any
148 provider offering it, within the criteria given by the I<properties>.
149 See L<crypto(7)/ALGORITHM FETCHING> for further information.
151 The returned value must eventually be freed with EVP_MD_free().
153 Fetched B<EVP_MD> structures are reference counted.
155 =item EVP_MD_up_ref()
157 Increments the reference count for an B<EVP_MD> structure.
161 Decrements the reference count for the fetched B<EVP_MD> structure.
162 If the reference count drops to 0 then the structure is freed.
164 =item EVP_MD_CTX_new()
166 Allocates and returns a digest context.
168 =item EVP_MD_CTX_reset()
170 Resets the digest context I<ctx>. This can be used to reuse an already
173 =item EVP_MD_CTX_free()
175 Cleans up digest context I<ctx> and frees up the space allocated to it.
177 =item EVP_MD_CTX_ctrl()
179 I<This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
180 is the mechanism that should be used to set and get parameters that are used by
183 Performs digest-specific control actions on context I<ctx>. The control command
184 is indicated in I<cmd> and any additional arguments in I<p1> and I<p2>.
185 EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex2(). Other restrictions
186 may apply depending on the control type and digest implementation.
188 If this function happens to be used with a fetched B<EVP_MD>, it will
189 translate the controls that are known to OpenSSL into L<OSSL_PARAM(3)>
190 parameters with keys defined by OpenSSL and call EVP_MD_CTX_get_params() or
191 EVP_MD_CTX_set_params() as is appropriate for each control command.
193 See L</CONTROLS> below for more information, including what translations are
196 =item EVP_MD_get_params()
198 Retrieves the requested list of I<params> from a MD I<md>.
199 See L</PARAMETERS> below for more information.
201 =item EVP_MD_CTX_get_params()
203 Retrieves the requested list of I<params> from a MD context I<ctx>.
204 See L</PARAMETERS> below for more information.
206 =item EVP_MD_CTX_set_params()
208 Sets the list of I<params> into a MD context I<ctx>.
209 See L</PARAMETERS> below for more information.
211 =item EVP_MD_gettable_params()
213 Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters
214 that can be used with EVP_MD_get_params().
216 =item EVP_MD_gettable_ctx_params(), EVP_MD_CTX_gettable_params()
218 Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters
219 that can be used with EVP_MD_CTX_get_params(). EVP_MD_gettable_ctx_params()
220 returns the parameters that can be retrieved from the algorithm, whereas
221 EVP_MD_CTX_gettable_params() returns the parameters that can be retrieved
222 in the context's current state.
224 =item EVP_MD_settable_ctx_params(), EVP_MD_CTX_settable_params()
226 Get a constant L<OSSL_PARAM(3)> array that describes the settable parameters
227 that can be used with EVP_MD_CTX_set_params(). EVP_MD_settable_ctx_params()
228 returns the parameters that can be set from the algorithm, whereas
229 EVP_MD_CTX_settable_params() returns the parameters that can be set in the
230 context's current state.
232 =item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
234 Sets, clears and tests I<ctx> flags. See L</FLAGS> below for more information.
236 =item EVP_Q_digest() is a quick one-shot digest function.
238 It hashes I<datalen> bytes of data at I<data> using the digest algorithm
239 I<name>, which is fetched using the optional I<libctx> and I<propq> parameters.
240 The digest value is placed in I<md> and its length is written at I<mdlen>
241 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
245 A wrapper around the Digest Init_ex, Update and Final_ex functions.
246 Hashes I<count> bytes of data at I<data> using a digest I<type> from ENGINE
247 I<impl>. The digest value is placed in I<md> and its length is written at I<size>
248 if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
249 If I<impl> is NULL the default implementation of digest I<type> is used.
251 =item EVP_DigestInit_ex2()
253 Sets up digest context I<ctx> to use a digest I<type>.
254 I<type> is typically supplied by a function such as EVP_sha1(), or a
255 value explicitly fetched with EVP_MD_fetch().
257 The parameters B<params> are set on the context after initialisation.
259 The I<type> parameter can be NULL if I<ctx> has been already initialized
260 with another EVP_DigestInit_ex() call and has not been reset with
263 =item EVP_DigestInit_ex()
265 Sets up digest context I<ctx> to use a digest I<type>.
266 I<type> is typically supplied by a function such as EVP_sha1(), or a
267 value explicitly fetched with EVP_MD_fetch().
269 If I<impl> is non-NULL, its implementation of the digest I<type> is used if
270 there is one, and if not, the default implementation is used.
272 The I<type> parameter can be NULL if I<ctx> has been already initialized
273 with another EVP_DigestInit_ex() call and has not been reset with
276 =item EVP_DigestUpdate()
278 Hashes I<cnt> bytes of data at I<d> into the digest context I<ctx>. This
279 function can be called several times on the same I<ctx> to hash additional
282 =item EVP_DigestFinal_ex()
284 Retrieves the digest value from I<ctx> and places it in I<md>. If the I<s>
285 parameter is not NULL then the number of bytes of data written (i.e. the
286 length of the digest) will be written to the integer at I<s>, at most
287 B<EVP_MAX_MD_SIZE> bytes will be written unless the digest implementation
288 allows changing the digest size and it is set to a larger value by the
289 application. After calling EVP_DigestFinal_ex() no additional calls to
290 EVP_DigestUpdate() can be made, but EVP_DigestInit_ex2() can be called to
291 initialize a new digest operation.
293 =item EVP_DigestFinalXOF()
295 Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
296 It retrieves the digest value from I<ctx> and places it in I<outlen>-sized I<out>.
297 After calling this function no additional calls to EVP_DigestUpdate() can be
298 made, but EVP_DigestInit_ex2() can be called to initialize a new operation.
299 EVP_DigestFinalXOF() may only be called once
301 =item EVP_DigestSqueeze()
303 Similar to EVP_DigestFinalXOF() but allows multiple calls to be made to
304 squeeze variable length output data.
305 EVP_DigestFinalXOF() should not be called after this.
307 =item EVP_MD_CTX_dup()
309 Can be used to duplicate the message digest state from I<in>. This is useful
310 to avoid multiple EVP_MD_fetch() calls or if large amounts of data are to be
311 hashed which only differ in the last few bytes.
313 =item EVP_MD_CTX_copy_ex()
315 Can be used to copy the message digest state from I<in> to I<out>. This is
316 useful if large amounts of data are to be hashed which only differ in the last
319 =item EVP_DigestInit()
321 Behaves in the same way as EVP_DigestInit_ex2() except it doesn't set any
322 parameters and calls EVP_MD_CTX_reset() so it cannot be used with an I<type>
325 =item EVP_DigestFinal()
327 Similar to EVP_DigestFinal_ex() except after computing the digest
328 the digest context I<ctx> is automatically cleaned up with EVP_MD_CTX_reset().
330 =item EVP_MD_CTX_copy()
332 Similar to EVP_MD_CTX_copy_ex() except the destination I<out> does not have to
337 Returns 1 if I<md> is an implementation of an algorithm that's
338 identifiable with I<name>, otherwise 0.
340 If I<md> is a legacy digest (it's the return value from the likes of
341 EVP_sha256() rather than the result of an EVP_MD_fetch()), only cipher
342 names registered with the default library context (see
343 L<OSSL_LIB_CTX(3)>) will be considered.
345 =item EVP_MD_get0_name(),
346 EVP_MD_CTX_get0_name()
348 Return the name of the given message digest. For fetched message
349 digests with multiple names, only one of them is returned; it's
350 recommended to use EVP_MD_names_do_all() instead.
352 =item EVP_MD_names_do_all()
354 Traverses all names for the I<md>, and calls I<fn> with each name and
355 I<data>. This is only useful with fetched B<EVP_MD>s.
357 =item EVP_MD_get0_description()
359 Returns a description of the digest, meant for display and human consumption.
360 The description is at the discretion of the digest implementation.
362 =item EVP_MD_get0_provider()
364 Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given
367 =item EVP_MD_get_size(),
368 EVP_MD_CTX_get_size()
370 Return the size of the message digest when passed an B<EVP_MD> or an
371 B<EVP_MD_CTX> structure, i.e. the size of the hash.
373 =item EVP_MD_get_block_size(),
374 EVP_MD_CTX_get_block_size()
376 Return the block size of the message digest when passed an B<EVP_MD> or an
377 B<EVP_MD_CTX> structure.
379 =item EVP_MD_get_type(),
380 EVP_MD_CTX_get_type()
382 Return the NID of the OBJECT IDENTIFIER representing the given message digest
383 when passed an B<EVP_MD> structure. For example, C<EVP_MD_get_type(EVP_sha1())>
384 returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
386 =item EVP_MD_CTX_get0_md_data()
388 Return the digest method private data for the passed B<EVP_MD_CTX>.
389 The space is allocated by OpenSSL and has the size originally set with
390 EVP_MD_meth_set_app_datasize().
392 =item EVP_MD_CTX_get0_md(), EVP_MD_CTX_get1_md()
394 EVP_MD_CTX_get0_md() returns
395 the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
396 will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex2() (or
397 other similar function) when the EVP_MD_CTX was first initialised. Note that
398 where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
399 this function will not have its reference count incremented and therefore it
400 should not be used after the EVP_MD_CTX is freed.
401 EVP_MD_CTX_get1_md() is the same except the ownership is passed to the
402 caller and is from the passed B<EVP_MD_CTX>.
404 =item EVP_MD_CTX_set_update_fn()
406 Sets the update function for I<ctx> to I<update>.
407 This is the function that is called by EVP_DigestUpdate(). If not set, the
408 update function from the B<EVP_MD> type specified at initialization is used.
410 =item EVP_MD_CTX_update_fn()
412 Returns the update function for I<ctx>.
414 =item EVP_MD_get_flags()
416 Returns the I<md> flags. Note that these are different from the B<EVP_MD_CTX>
417 ones. See L<EVP_MD_meth_set_flags(3)> for more information.
419 =item EVP_MD_get_pkey_type()
421 Returns the NID of the public key signing algorithm associated with this
422 digest. For example EVP_sha1() is associated with RSA so this will return
423 B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
424 longer linked this function is only retained for compatibility reasons.
428 A "null" message digest that does nothing: i.e. the hash it returns is of zero
431 =item EVP_get_digestbyname(),
432 EVP_get_digestbynid(),
433 EVP_get_digestbyobj()
435 Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
436 B<ASN1_OBJECT> structure respectively.
438 The EVP_get_digestbyname() function is present for backwards compatibility with
439 OpenSSL prior to version 3 and is different to the EVP_MD_fetch() function
440 since it does not attempt to "fetch" an implementation of the cipher.
441 Additionally, it only knows about digests that are built-in to OpenSSL and have
442 an associated NID. Similarly EVP_get_digestbynid() and EVP_get_digestbyobj()
443 also return objects without an associated implementation.
445 When the digest objects returned by these functions are used (such as in a call
446 to EVP_DigestInit_ex()) an implementation of the digest will be implicitly
447 fetched from the loaded providers. This fetch could fail if no suitable
448 implementation is available. Use EVP_MD_fetch() instead to explicitly fetch
449 the algorithm and an associated implementation from a provider.
451 See L<crypto(7)/ALGORITHM FETCHING> for more information about fetching.
453 The digest objects returned from these functions do not need to be freed with
456 =item EVP_MD_CTX_get_pkey_ctx()
458 Returns the B<EVP_PKEY_CTX> assigned to I<ctx>. The returned pointer should not
459 be freed by the caller.
461 =item EVP_MD_CTX_set_pkey_ctx()
463 Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
464 a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
465 L<EVP_DigestVerifyInit(3)>. The I<pctx> passed to this function should be freed
466 by the caller. A NULL I<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
467 assigned to I<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
468 depends on how the B<EVP_PKEY_CTX> is created.
470 =item EVP_MD_do_all_provided()
472 Traverses all messages digests implemented by all activated providers
473 in the given library context I<libctx>, and for each of the implementations,
474 calls the given function I<fn> with the implementation method and the given
481 See L<OSSL_PARAM(3)> for information about passing parameters.
483 EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
487 =item "xoflen" (B<OSSL_DIGEST_PARAM_XOFLEN>) <unsigned integer>
489 Sets the digest length for extendable output functions.
490 The value should not exceed what can be given using a B<size_t>.
491 It may be used by BLAKE2B-512, SHAKE-128 and SHAKE-256 to set the
492 output length used by EVP_DigestFinal_ex() and EVP_DigestFinal().
494 =item "pad-type" (B<OSSL_DIGEST_PARAM_PAD_TYPE>) <unsigned integer>
496 Sets the padding type.
497 It is used by the MDC2 algorithm.
501 EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
505 =item "micalg" (B<OSSL_PARAM_DIGEST_KEY_MICALG>) <UTF8 string>.
507 Gets the digest Message Integrity Check algorithm string. This is used when
508 creating S/MIME multipart/signed messages, as specified in RFC 3851.
509 It may be used by external engines or providers.
515 EVP_MD_CTX_ctrl() can be used to send the following standard controls:
519 =item EVP_MD_CTRL_MICALG
521 Gets the digest Message Integrity Check algorithm string. This is used when
522 creating S/MIME multipart/signed messages, as specified in RFC 3851.
523 The string value is written to I<p2>.
525 When used with a fetched B<EVP_MD>, EVP_MD_CTX_get_params() gets called with
526 an L<OSSL_PARAM(3)> item with the key "micalg" (B<OSSL_DIGEST_PARAM_MICALG>).
528 =item EVP_MD_CTRL_XOF_LEN
530 This control sets the digest length for extendable output functions to I<p1>.
531 Sending this control directly should not be necessary, the use of
532 EVP_DigestFinalXOF() is preferred.
533 Currently used by SHAKE.
535 When used with a fetched B<EVP_MD>, EVP_MD_CTX_get_params() gets called with
536 an L<OSSL_PARAM(3)> item with the key "xoflen" (B<OSSL_DIGEST_PARAM_XOFLEN>).
542 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
543 can be used the manipulate and test these B<EVP_MD_CTX> flags:
547 =item EVP_MD_CTX_FLAG_ONESHOT
549 This flag instructs the digest to optimize for one update only, if possible.
551 =for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
553 =for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
555 =for comment We currently avoid documenting flags that are only bit holder:
556 EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
558 =item EVP_MD_CTX_FLAG_NO_INIT
560 This flag instructs EVP_DigestInit() and similar not to initialise the
561 implementation specific data.
563 =item EVP_MD_CTX_FLAG_FINALISE
565 Some functions such as EVP_DigestSign only finalise copies of internal
566 contexts so additional data can be included after the finalisation call.
567 This is inefficient if this functionality is not required, and can be
568 disabled with this flag.
578 Returns a pointer to a B<EVP_MD> for success or NULL for failure.
580 =item EVP_MD_up_ref()
582 Returns 1 for success or 0 for failure.
584 =item EVP_Q_digest(),
586 EVP_DigestInit_ex2(),
590 EVP_DigestFinal_ex(),
591 EVP_DigestFinalXOF(), and
595 success and 0 for failure.
597 =item EVP_MD_CTX_ctrl()
599 Returns 1 if successful or 0 for failure.
601 =item EVP_MD_CTX_set_params(),
602 EVP_MD_CTX_get_params()
604 Returns 1 if successful or 0 for failure.
606 =item EVP_MD_CTX_settable_params(),
607 EVP_MD_CTX_gettable_params()
609 Return an array of constant L<OSSL_PARAM(3)>s, or NULL if there is none
612 =item EVP_MD_CTX_dup()
614 Returns a new EVP_MD_CTX if successful or NULL on failure.
616 =item EVP_MD_CTX_copy_ex()
618 Returns 1 if successful or 0 for failure.
620 =item EVP_MD_get_type(),
621 EVP_MD_get_pkey_type()
623 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
626 =item EVP_MD_get_size(),
627 EVP_MD_get_block_size(),
628 EVP_MD_CTX_get_size(),
629 EVP_MD_CTX_get_block_size()
631 Returns the digest or block size in bytes or -1 for failure.
635 Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
637 =item EVP_get_digestbyname(),
638 EVP_get_digestbynid(),
639 EVP_get_digestbyobj()
641 Returns either an B<EVP_MD> structure or NULL if an error occurs.
643 =item EVP_MD_CTX_set_pkey_ctx()
645 This function has no return value.
647 =item EVP_MD_names_do_all()
649 Returns 1 if the callback was called for all names. A return value of 0 means
650 that the callback was not called for any names.
656 The B<EVP> interface to message digests should almost always be used in
657 preference to the low-level interfaces. This is because the code then becomes
658 transparent to the digest used and much more flexible.
660 New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
661 digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
662 are still in common use.
664 For most applications the I<impl> parameter to EVP_DigestInit_ex() will be
665 set to NULL to use the default digest implementation.
667 Ignoring failure returns of EVP_DigestInit_ex(), EVP_DigestInit_ex2(), or
668 EVP_DigestInit() can lead to undefined behavior on subsequent calls
669 updating or finalizing the B<EVP_MD_CTX> such as the EVP_DigestUpdate() or
670 EVP_DigestFinal() functions. The only valid calls on the B<EVP_MD_CTX>
671 when initialization fails are calls that attempt another initialization of
672 the context or release the context.
674 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
675 obsolete but are retained to maintain compatibility with existing code. New
676 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
677 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
678 instead of initializing and cleaning it up on each call and allow non default
679 implementations of digests to be specified.
681 If digest contexts are not cleaned up after use,
682 memory leaks will occur.
684 EVP_MD_CTX_get0_name(), EVP_MD_CTX_get_size(), EVP_MD_CTX_get_block_size(),
685 EVP_MD_CTX_get_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are
688 EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
693 This example digests the data "Test Message\n" and "Hello World\n", using the
694 digest name passed on the command line.
698 #include <openssl/evp.h>
700 int main(int argc, char *argv[])
704 char mess1[] = "Test Message\n";
705 char mess2[] = "Hello World\n";
706 unsigned char md_value[EVP_MAX_MD_SIZE];
707 unsigned int md_len, i;
709 if (argv[1] == NULL) {
710 printf("Usage: mdtest digestname\n");
714 md = EVP_get_digestbyname(argv[1]);
716 printf("Unknown message digest %s\n", argv[1]);
720 mdctx = EVP_MD_CTX_new();
721 if (!EVP_DigestInit_ex2(mdctx, md, NULL)) {
722 printf("Message digest initialization failed.\n");
723 EVP_MD_CTX_free(mdctx);
726 if (!EVP_DigestUpdate(mdctx, mess1, strlen(mess1))) {
727 printf("Message digest update failed.\n");
728 EVP_MD_CTX_free(mdctx);
731 if (!EVP_DigestUpdate(mdctx, mess2, strlen(mess2))) {
732 printf("Message digest update failed.\n");
733 EVP_MD_CTX_free(mdctx);
736 if (!EVP_DigestFinal_ex(mdctx, md_value, &md_len)) {
737 printf("Message digest finalization failed.\n");
738 EVP_MD_CTX_free(mdctx);
741 EVP_MD_CTX_free(mdctx);
743 printf("Digest is: ");
744 for (i = 0; i < md_len; i++)
745 printf("%02x", md_value[i]);
753 L<EVP_MD_meth_new(3)>,
759 L<crypto(7)/ALGORITHM FETCHING>,
760 L<provider-digest(7)>,
761 L<life_cycle-digest(7)>
763 The full list of digest algorithms are provided below.
765 L<EVP_blake2b512(3)>,
779 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
780 EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
782 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
783 later, so now EVP_sha1() can be used with RSA and DSA.
785 The EVP_dss1() function was removed in OpenSSL 1.1.0.
787 The EVP_MD_CTX_set_pkey_ctx() function was added in OpenSSL 1.1.1.
789 The EVP_Q_digest(), EVP_DigestInit_ex2(),
790 EVP_MD_fetch(), EVP_MD_free(), EVP_MD_up_ref(),
791 EVP_MD_get_params(), EVP_MD_CTX_set_params(), EVP_MD_CTX_get_params(),
792 EVP_MD_gettable_params(), EVP_MD_gettable_ctx_params(),
793 EVP_MD_settable_ctx_params(), EVP_MD_CTX_settable_params() and
794 EVP_MD_CTX_gettable_params() functions were added in OpenSSL 3.0.
796 The EVP_MD_type(), EVP_MD_nid(), EVP_MD_name(), EVP_MD_pkey_type(),
797 EVP_MD_size(), EVP_MD_block_size(), EVP_MD_flags(), EVP_MD_CTX_size(),
798 EVP_MD_CTX_block_size(), EVP_MD_CTX_type(), and EVP_MD_CTX_md_data()
799 functions were renamed to include C<get> or C<get0> in their names in
800 OpenSSL 3.0, respectively. The old names are kept as non-deprecated
803 The EVP_MD_CTX_md() function was deprecated in OpenSSL 3.0; use
804 EVP_MD_CTX_get0_md() instead.
805 EVP_MD_CTX_update_fn() and EVP_MD_CTX_set_update_fn() were deprecated
808 The functions EVP_MD_CTX_dup() and EVP_DigestSqueeze() were added in
813 Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
815 Licensed under the Apache License 2.0 (the "License"). You may not use
816 this file except in compliance with the License. You can obtain a copy
817 in the file LICENSE in the source distribution or at
818 L<https://www.openssl.org/source/license.html>.