summaryrefslogtreecommitdiff
path: root/src/lib/libcrypto/doc/EVP_DigestInit.pod
diff options
context:
space:
mode:
Diffstat (limited to 'src/lib/libcrypto/doc/EVP_DigestInit.pod')
-rw-r--r--src/lib/libcrypto/doc/EVP_DigestInit.pod278
1 files changed, 0 insertions, 278 deletions
diff --git a/src/lib/libcrypto/doc/EVP_DigestInit.pod b/src/lib/libcrypto/doc/EVP_DigestInit.pod
deleted file mode 100644
index ccb19fc0a7..0000000000
--- a/src/lib/libcrypto/doc/EVP_DigestInit.pod
+++ /dev/null
@@ -1,278 +0,0 @@
1=pod
2
3=head1 NAME
4
5EVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUpdate,
6EVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE,
7EVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type,
8EVP_MD_size, EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size,
9EVP_MD_CTX_block_size, EVP_MD_CTX_type, EVP_md_null, EVP_md2, EVP_md5, EVP_sha,
10EVP_sha1, EVP_sha224, EVP_sha256, EVP_sha384, EVP_sha512, EVP_dss, EVP_dss1,
11EVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid,
12EVP_get_digestbyobj - EVP digest routines
13
14=head1 SYNOPSIS
15
16 #include <openssl/evp.h>
17
18 void EVP_MD_CTX_init(EVP_MD_CTX *ctx);
19 EVP_MD_CTX *EVP_MD_CTX_create(void);
20
21 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
22 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
23 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md,
24 unsigned int *s);
25
26 int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);
27 void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);
28
29 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in);
30
31 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
32 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md,
33 unsigned int *s);
34
35 int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in);
36
37 #define EVP_MAX_MD_SIZE 64 /* SHA512 */
38
39 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
44 const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
45 #define EVP_MD_CTX_size(e) EVP_MD_size(EVP_MD_CTX_md(e))
46 #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest)
47 #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest)
48
49 const EVP_MD *EVP_md_null(void);
50 const EVP_MD *EVP_md2(void);
51 const EVP_MD *EVP_md5(void);
52 const EVP_MD *EVP_sha(void);
53 const EVP_MD *EVP_sha1(void);
54 const EVP_MD *EVP_dss(void);
55 const EVP_MD *EVP_dss1(void);
56 const EVP_MD *EVP_ripemd160(void);
57
58 const EVP_MD *EVP_sha224(void);
59 const EVP_MD *EVP_sha256(void);
60 const EVP_MD *EVP_sha384(void);
61 const EVP_MD *EVP_sha512(void);
62
63 const EVP_MD *EVP_get_digestbyname(const char *name);
64 #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a))
65 #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a))
66
67=head1 DESCRIPTION
68
69The EVP digest routines are a high level interface to message digests.
70
71EVP_MD_CTX_init() initializes digest context B<ctx>.
72
73EVP_MD_CTX_create() allocates, initializes and returns a digest context.
74
75EVP_DigestInit_ex() sets up digest context B<ctx> to use a digest
76B<type> from ENGINE B<impl>. B<ctx> must be initialized before calling this
77function. B<type> will typically be supplied by a function such as EVP_sha1().
78If B<impl> is NULL then the default implementation of digest B<type> is used.
79
80EVP_DigestUpdate() hashes B<cnt> bytes of data at B<d> into the
81digest context B<ctx>. This function can be called several times on the
82same B<ctx> to hash additional data.
83
84EVP_DigestFinal_ex() retrieves the digest value from B<ctx> and places
85it in B<md>. If the B<s> parameter is not NULL then the number of
86bytes of data written (i.e. the length of the digest) will be written
87to the integer at B<s>, at most B<EVP_MAX_MD_SIZE> bytes will be written.
88After calling EVP_DigestFinal_ex() no additional calls to EVP_DigestUpdate()
89can be made, but EVP_DigestInit_ex() can be called to initialize a new
90digest operation.
91
92EVP_MD_CTX_cleanup() cleans up digest context B<ctx>, it should be called
93after a digest context is no longer needed.
94
95EVP_MD_CTX_destroy() cleans up digest context B<ctx> and frees up the
96space allocated to it, it should be called only on a context created
97using EVP_MD_CTX_create().
98
99EVP_MD_CTX_copy_ex() can be used to copy the message digest state from
100B<in> to B<out>. This is useful if large amounts of data are to be
101hashed which only differ in the last few bytes. B<out> must be initialized
102before calling this function.
103
104EVP_DigestInit() behaves in the same way as EVP_DigestInit_ex() except
105the passed context B<ctx> does not have to be initialized, and it always
106uses the default digest implementation.
107
108EVP_DigestFinal() is similar to EVP_DigestFinal_ex() except the digest
109context B<ctx> is automatically cleaned up.
110
111EVP_MD_CTX_copy() is similar to EVP_MD_CTX_copy_ex() except the destination
112B<out> does not have to be initialized.
113
114EVP_MD_size() and EVP_MD_CTX_size() return the size of the message digest
115when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure, i.e. the size of the
116hash.
117
118EVP_MD_block_size() and EVP_MD_CTX_block_size() return the block size of the
119message digest when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure.
120
121EVP_MD_type() and EVP_MD_CTX_type() return the NID of the OBJECT IDENTIFIER
122representing the given message digest when passed an B<EVP_MD> structure.
123For example EVP_MD_type(EVP_sha1()) returns B<NID_sha1>. This function is
124normally used when setting ASN1 OIDs.
125
126EVP_MD_CTX_md() returns the B<EVP_MD> structure corresponding to the passed
127B<EVP_MD_CTX>.
128
129EVP_MD_pkey_type() returns the NID of the public key signing algorithm
130associated with this digest. For example EVP_sha1() is associated with RSA so
131this will return B<NID_sha1WithRSAEncryption>. Since digests and signature
132algorithms are no longer linked this function is only retained for
133compatibility reasons.
134
135EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_sha224(), EVP_sha256(),
136EVP_sha384(), EVP_sha512() and EVP_ripemd160() return B<EVP_MD>
137structures for the MD2, MD5, SHA, SHA1, SHA224, SHA256, SHA384, SHA512
138and RIPEMD160 digest algorithms respectively.
139
140EVP_dss() and EVP_dss1() return B<EVP_MD> structures for SHA and SHA1 digest
141algorithms but using DSS (DSA) for the signature algorithm. Note: there is
142no need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are
143however retained for compatibility.
144
145EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it
146returns is of zero length.
147
148EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
149return an B<EVP_MD> structure when passed a digest name, a digest NID or
150an ASN1_OBJECT structure respectively. The digest table must be initialized
151using, for example, OpenSSL_add_all_digests() for these functions to work.
152
153=head1 RETURN VALUES
154
155EVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for
156success and 0 for failure.
157
158EVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure.
159
160EVP_MD_type(), EVP_MD_pkey_type() and EVP_MD_type() return the NID of the
161corresponding OBJECT IDENTIFIER or NID_undef if none exists.
162
163EVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size() and
164EVP_MD_CTX_block_size() return the digest or block size in bytes.
165
166EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(),
167EVP_dss1() and EVP_ripemd160() return pointers to the
168corresponding EVP_MD structures.
169
170EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
171return either an B<EVP_MD> structure or NULL if an error occurs.
172
173=head1 NOTES
174
175The B<EVP> interface to message digests should almost always be used in
176preference to the low level interfaces. This is because the code then becomes
177transparent to the digest used and much more flexible.
178
179New applications should use the SHA2 digest algorithms such as SHA256.
180The other digest algorithms are still in common use.
181
182For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
183set to NULL to use the default digest implementation.
184
185The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
186obsolete but are retained to maintain compatibility with existing code. New
187applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
188EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
189instead of initializing and cleaning it up on each call and allow non default
190implementations of digests to be specified.
191
192In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use
193memory leaks will occur.
194
195Stack allocation of EVP_MD_CTX structures is common, for example:
196
197 EVP_MD_CTX mctx;
198 EVP_MD_CTX_init(&mctx);
199
200This will cause binary compatibility issues if the size of EVP_MD_CTX
201structure changes (this will only happen with a major release of OpenSSL).
202Applications wishing to avoid this should use EVP_MD_CTX_create() instead:
203
204 EVP_MD_CTX *mctx;
205 mctx = EVP_MD_CTX_create();
206
207
208=head1 EXAMPLE
209
210This example digests the data "Test Message\n" and "Hello World\n", using the
211digest name passed on the command line.
212
213 #include <stdio.h>
214 #include <openssl/evp.h>
215
216 int
217 main(int argc, char *argv[])
218 {
219 EVP_MD_CTX *mdctx;
220 const EVP_MD *md;
221 const char mess1[] = "Test Message\n";
222 const char mess2[] = "Hello World\n";
223 unsigned char md_value[EVP_MAX_MD_SIZE];
224 int md_len, i;
225
226 OpenSSL_add_all_digests();
227
228 if (argc <= 1) {
229 printf("Usage: mdtest digestname\n");
230 exit(1);
231 }
232
233 md = EVP_get_digestbyname(argv[1]);
234 if (md == NULL) {
235 printf("Unknown message digest %s\n", argv[1]);
236 exit(1);
237 }
238
239 mdctx = EVP_MD_CTX_create();
240 EVP_DigestInit_ex(mdctx, md, NULL);
241 EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
242 EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
243 EVP_DigestFinal_ex(mdctx, md_value, &md_len);
244 EVP_MD_CTX_destroy(mdctx);
245
246 printf("Digest is: ");
247 for(i = 0; i < md_len; i++)
248 printf("%02x", md_value[i]);
249 printf("\n");
250 }
251
252=head1 SEE ALSO
253
254L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
255L<md5(3)|md5(3)>, L<ripemd(3)|ripemd(3)>,
256L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
257
258=head1 HISTORY
259
260EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are
261available in all versions of SSLeay and OpenSSL.
262
263EVP_MD_CTX_init(), EVP_MD_CTX_create(), EVP_MD_CTX_copy_ex(),
264EVP_MD_CTX_cleanup(), EVP_MD_CTX_destroy(), EVP_DigestInit_ex()
265and EVP_DigestFinal_ex() were added in OpenSSL 0.9.7.
266
267EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(),
268EVP_dss(), EVP_dss1() and EVP_ripemd160() were
269changed to return truely const EVP_MD * in OpenSSL 0.9.7.
270
271The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
272later, so now EVP_sha1() can be used with RSA and DSA, there is no need to
273use EVP_dss1() any more.
274
275OpenSSL 1.0 and later does not include the MD2 digest algorithm in the
276default configuration due to its security weaknesses.
277
278=cut