1EVP_DIGESTINIT(3) OpenSSL EVP_DIGESTINIT(3)
2
6 EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy_ex,
7 EVP_MD_CTX_ctrl, EVP_MD_CTX_set_flags, EVP_MD_CTX_clear_flags,
8 EVP_MD_CTX_test_flags, EVP_DigestInit_ex, EVP_DigestInit,
9 EVP_DigestUpdate, EVP_DigestFinal_ex, EVP_DigestFinalXOF,
10 EVP_DigestFinal, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type,
11 EVP_MD_size, EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size,
12 EVP_MD_CTX_block_size, EVP_MD_CTX_type, EVP_MD_CTX_md_data,
13 EVP_md_null, EVP_get_digestbyname, EVP_get_digestbynid,
14 EVP_get_digestbyobj, EVP_MD_CTX_set_pkey_ctx - EVP digest routines
15
17 #include <openssl/evp.h>
18 EVP_MD_CTX *EVP_MD_CTX_new(void);
20 int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
21 void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
22 void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
23 void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
24 void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
25 int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
26 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
28 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
29 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
30 int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
31 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
33 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
35 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
36 int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
38 int EVP_MD_type(const EVP_MD *md);
40 int EVP_MD_pkey_type(const EVP_MD *md);
41 int EVP_MD_size(const EVP_MD *md);
42 int EVP_MD_block_size(const EVP_MD *md);
43 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
45 int EVP_MD_CTX_size(const EVP_MD *ctx);
46 int EVP_MD_CTX_block_size(const EVP_MD *ctx);
47 int EVP_MD_CTX_type(const EVP_MD *ctx);
48 void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
49 const EVP_MD *EVP_md_null(void);
51 const EVP_MD *EVP_get_digestbyname(const char *name);
53 const EVP_MD *EVP_get_digestbynid(int type);
54 const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
55 void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
57
59 The EVP digest routines are a high level interface to message digests,
60 and should be used instead of the cipher-specific functions.
61 EVP_MD_CTX_new()
63 Allocates and returns a digest context.
64 EVP_MD_CTX_reset()
66 Resets the digest context ctx. This can be used to reuse an
67 already existing context.
68 EVP_MD_CTX_free()
70 Cleans up digest context ctx and frees up the space allocated to
71 it.
72 EVP_MD_CTX_ctrl()
74 Performs digest-specific control actions on context ctx.
75 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(),
77 EVP_MD_CTX_test_flags()
78 Sets, clears and tests ctx flags. See "FLAGS" below for more
79 information.
80 EVP_DigestInit_ex()
82 Sets up digest context ctx to use a digest type from ENGINE impl.
83 type will typically be supplied by a function such as EVP_sha1().
84 If impl is NULL then the default implementation of digest type is
85 used.
86 EVP_DigestUpdate()
88 Hashes cnt bytes of data at d into the digest context ctx. This
89 function can be called several times on the same ctx to hash
90 additional data.
91 EVP_DigestFinal_ex()
93 Retrieves the digest value from ctx and places it in md. If the s
94 parameter is not NULL then the number of bytes of data written
95 (i.e. the length of the digest) will be written to the integer at
96 s, at most EVP_MAX_MD_SIZE bytes will be written. After calling
97 EVP_DigestFinal_ex() no additional calls to EVP_DigestUpdate() can
98 be made, but EVP_DigestInit_ex() can be called to initialize a new
99 digest operation.
100 EVP_DigestFinalXOF()
102 Interfaces to extendable-output functions, XOFs, such as SHAKE128
103 and SHAKE256. It retrieves the digest value from ctx and places it
104 in len-sized <B>md. After calling this function no additional
105 calls to EVP_DigestUpdate() can be made, but EVP_DigestInit_ex()
106 can be called to initialize a new operation.
107 EVP_MD_CTX_copy_ex()
109 Can be used to copy the message digest state from in to out. This
110 is useful if large amounts of data are to be hashed which only
111 differ in the last few bytes.
112 EVP_DigestInit()
114 Behaves in the same way as EVP_DigestInit_ex() except it always
115 uses the default digest implementation.
116 EVP_DigestFinal()
118 Similar to EVP_DigestFinal_ex() except the digest context ctx is
119 automatically cleaned up.
120 EVP_MD_CTX_copy()
122 Similar to EVP_MD_CTX_copy_ex() except the destination out does not
123 have to be initialized.
124 EVP_MD_size(), EVP_MD_CTX_size()
126 Return the size of the message digest when passed an EVP_MD or an
127 EVP_MD_CTX structure, i.e. the size of the hash.
128 EVP_MD_block_size(), EVP_MD_CTX_block_size()
130 Return the block size of the message digest when passed an EVP_MD
131 or an EVP_MD_CTX structure.
132 EVP_MD_type(), EVP_MD_CTX_type()
134 Return the NID of the OBJECT IDENTIFIER representing the given
135 message digest when passed an EVP_MD structure. For example,
136 "EVP_MD_type(EVP_sha1())" returns NID_sha1. This function is
137 normally used when setting ASN1 OIDs.
138 EVP_MD_CTX_md_data()
140 Return the digest method private data for the passed EVP_MD_CTX.
141 The space is allocated by OpenSSL and has the size originally set
142 with EVP_MD_meth_set_app_datasize().
143 EVP_MD_CTX_md()
145 Returns the EVP_MD structure corresponding to the passed
146 EVP_MD_CTX.
147 EVP_MD_pkey_type()
149 Returns the NID of the public key signing algorithm associated with
150 this digest. For example EVP_sha1() is associated with RSA so this
151 will return NID_sha1WithRSAEncryption. Since digests and signature
152 algorithms are no longer linked this function is only retained for
153 compatibility reasons.
154 EVP_md_null()
156 A "null" message digest that does nothing: i.e. the hash it returns
157 is of zero length.
158 EVP_get_digestbyname(), EVP_get_digestbynid(), EVP_get_digestbyobj()
160 Returns an EVP_MD structure when passed a digest name, a digest NID
161 or an ASN1_OBJECT structure respectively.
162 EVP_MD_CTX_set_pkey_ctx()
164 Assigns an EVP_PKEY_CTX to EVP_MD_CTX. This is usually used to
165 provide a customzied EVP_PKEY_CTX to EVP_DigestSignInit(3) or
166 EVP_DigestVerifyInit(3). The pctx passed to this function should be
167 freed by the caller. A NULL pctx pointer is also allowed to clear
168 the EVP_PKEY_CTX assigned to ctx. In such case, freeing the cleared
169 EVP_PKEY_CTX or not depends on how the EVP_PKEY_CTX is created.
170
172 EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and
173 EVP_MD_CTX_test_flags() can be used the manipulate and test these
174 EVP_MD_CTX flags:
175 EVP_MD_CTX_FLAG_ONESHOT
177 This flag instructs the digest to optimize for one update only, if
178 possible.
179 EVP_MD_CTX_FLAG_NO_INIT
181 This flag instructs EVP_DigestInit() and similar not to initialise
182 the implementation specific data.
183 EVP_MD_CTX_FLAG_FINALISE
185 Some functions such as EVP_DigestSign only finalise copies of
186 internal contexts so additional data can be included after the
187 finalisation call. This is inefficient if this functionality is
188 not required, and can be disabled with this flag.
189
191 EVP_DigestInit_ex(), EVP_DigestUpdate(), EVP_DigestFinal_ex()
192 Returns 1 for success and 0 for failure.
193 EVP_MD_CTX_ctrl()
195 Returns 1 if successful or 0 for failure.
196 EVP_MD_CTX_copy_ex()
198 Returns 1 if successful or 0 for failure.
199 EVP_MD_type(), EVP_MD_pkey_type(), EVP_MD_type()
201 Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef
202 if none exists.
203 EVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size(),
205 EVP_MD_CTX_block_size()
206 Returns the digest or block size in bytes.
207 EVP_md_null()
209 Returns a pointer to the EVP_MD structure of the "null" message
210 digest.
211 EVP_get_digestbyname(), EVP_get_digestbynid(), EVP_get_digestbyobj()
213 Returns either an EVP_MD structure or NULL if an error occurs.
214 EVP_MD_CTX_set_pkey_ctx()
216 This function has no return value.
217
219 The EVP interface to message digests should almost always be used in
220 preference to the low level interfaces. This is because the code then
221 becomes transparent to the digest used and much more flexible.
222 New applications should use the SHA-2 (such as EVP_sha256(3)) or the
224 SHA-3 digest algorithms (such as EVP_sha3_512(3)). The other digest
225 algorithms are still in common use.
226 For most applications the impl parameter to EVP_DigestInit_ex() will be
228 set to NULL to use the default digest implementation.
229 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy()
231 are obsolete but are retained to maintain compatibility with existing
232 code. New applications should use EVP_DigestInit_ex(),
233 EVP_DigestFinal_ex() and EVP_MD_CTX_copy_ex() because they can
234 efficiently reuse a digest context instead of initializing and cleaning
235 it up on each call and allow non default implementations of digests to
236 be specified.
237 If digest contexts are not cleaned up after use, memory leaks will
239 occur.
240 EVP_MD_CTX_size(), EVP_MD_CTX_block_size(), EVP_MD_CTX_type(),
242 EVP_get_digestbynid() and EVP_get_digestbyobj() are defined as macros.
243 EVP_MD_CTX_ctrl() sends commands to message digests for additional
245 configuration or control.
246
248 This example digests the data "Test Message\n" and "Hello World\n",
249 using the digest name passed on the command line.
250 #include <stdio.h>
252 #include <string.h>
253 #include <openssl/evp.h>
254 int main(int argc, char *argv[])
256 {
257 EVP_MD_CTX *mdctx;
258 const EVP_MD *md;
259 char mess1[] = "Test Message\n";
260 char mess2[] = "Hello World\n";
261 unsigned char md_value[EVP_MAX_MD_SIZE];
262 unsigned int md_len, i;
263 if (argv[1] == NULL) {
265 printf("Usage: mdtest digestname\n");
266 exit(1);
267 }
268 md = EVP_get_digestbyname(argv[1]);
270 if (md == NULL) {
271 printf("Unknown message digest %s\n", argv[1]);
272 exit(1);
273 }
274 mdctx = EVP_MD_CTX_new();
276 EVP_DigestInit_ex(mdctx, md, NULL);
277 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
278 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
279 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
280 EVP_MD_CTX_free(mdctx);
281 printf("Digest is: ");
283 for (i = 0; i < md_len; i++)
284 printf("%02x", md_value[i]);
285 printf("\n");
286 exit(0);
288 }
289
291 dgst(1), evp(7)
292 The full list of digest algorithms are provided below.
294 EVP_blake2b512(3), EVP_md2(3), EVP_md4(3), EVP_md5(3), EVP_mdc2(3),
296 EVP_ripemd160(3), EVP_sha1(3), EVP_sha224(3), EVP_sha3_224(3),
297 EVP_sm3(3), EVP_whirlpool(3)
298
300 The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed
301 to EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0,
302 respectively.
303 The link between digests and signing algorithms was fixed in OpenSSL
305 1.0 and later, so now EVP_sha1() can be used with RSA and DSA.
306 The EVP_dss1() function was removed in OpenSSL 1.1.0.
308 The EVP_MD_CTX_set_pkey_ctx() function was added in 1.1.1.
310
312 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
313 Licensed under the OpenSSL license (the "License"). You may not use
315 this file except in compliance with the License. You can obtain a copy
316 in the file LICENSE in the source distribution or at
317 <https://www.openssl.org/source/license.html>.
3181.1.1d 2019-10-03 EVP_DIGESTINIT(3)