| blob | 5a1f0685331a61f0b8027cf021722b68954498d1 |
1 .\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
2 .\"
3 .\" Standard preamble:
4 .\" ========================================================================
5 .de Sh \" Subsection heading
6 .br
7 .if t .Sp
8 .ne 5
9 .PP
10 \fB\\$1\fR
11 .PP
12 ..
13 .de Sp \" Vertical space (when we can't use .PP)
14 .if t .sp .5v
15 .if n .sp
16 ..
17 .de Vb \" Begin verbatim text
18 .ft CW
19 .nf
20 .ne \\$1
21 ..
22 .de Ve \" End verbatim text
23 .ft R
24 .fi
25 ..
26 .\" Set up some character translations and predefined strings. \*(-- will
27 .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
28 .\" double quote, and \*(R" will give a right double quote. | will give a
29 .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to
30 .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C'
31 .\" expand to `' in nroff, nothing in troff, for use with C<>.
32 .tr \(*W-|\(bv\*(Tr
33 .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
34 .ie n \{\
35 . ds -- \(*W-
36 . ds PI pi
37 . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
38 . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
39 . ds L" ""
40 . ds R" ""
41 . ds C` ""
42 . ds C' ""
43 'br\}
44 .el\{\
45 . ds -- \|\(em\|
46 . ds PI \(*p
47 . ds L" ``
48 . ds R" ''
49 'br\}
50 .\"
51 .\" If the F register is turned on, we'll generate index entries on stderr for
52 .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
53 .\" entries marked with X<> in POD. Of course, you'll have to process the
54 .\" output yourself in some meaningful fashion.
55 .if \nF \{\
56 . de IX
57 . tm Index:\\$1\t\\n%\t"\\$2"
58 ..
59 . nr % 0
60 . rr F
61 .\}
62 .\"
63 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
64 .\" way too many mistakes in technical documents.
65 .hy 0
66 .if n .na
67 .\"
68 .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
69 .\" Fear. Run. Save yourself. No user-serviceable parts.
70 . \" fudge factors for nroff and troff
71 .if n \{\
72 . ds #H 0
73 . ds #V .8m
74 . ds #F .3m
75 . ds #[ \f1
76 . ds #] \fP
77 .\}
78 .if t \{\
79 . ds #H ((1u-(\\\\n(.fu%2u))*.13m)
80 . ds #V .6m
81 . ds #F 0
82 . ds #[ \&
83 . ds #] \&
84 .\}
85 . \" simple accents for nroff and troff
86 .if n \{\
87 . ds ' \&
88 . ds ` \&
89 . ds ^ \&
90 . ds , \&
91 . ds ~ ~
92 . ds /
93 .\}
94 .if t \{\
95 . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
96 . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
97 . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
98 . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
99 . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
100 . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
101 .\}
102 . \" troff and (daisy-wheel) nroff accents
103 .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
104 .ds 8 \h'\*(#H'\(*b\h'-\*(#H'
105 .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
106 .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
107 .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
108 .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
109 .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
110 .ds ae a\h'-(\w'a'u*4/10)'e
111 .ds Ae A\h'-(\w'A'u*4/10)'E
112 . \" corrections for vroff
113 .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
114 .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
115 . \" for low resolution devices (crt and lpr)
116 .if \n(.H>23 .if \n(.V>19 \
117 \{\
118 . ds : e
119 . ds 8 ss
120 . ds o a
121 . ds d- d\h'-1'\(ga
122 . ds D- D\h'-1'\(hy
123 . ds th \o'bp'
124 . ds Th \o'LP'
125 . ds ae ae
126 . ds Ae AE
127 .\}
128 .rm #[ #] #H #V #F C
129 .\" ========================================================================
130 .\"
131 .IX Title "EVP_DigestInit 3"
132 .TH EVP_DigestInit 3 "2009-07-23" "0.9.8k" "OpenSSL"
133 .SH "NAME"
134 EVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUpdate,
135 EVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE,
136 EVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size,
137 EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size, EVP_MD_CTX_block_size, EVP_MD_CTX_type,
138 EVP_md_null, EVP_md2, EVP_md5, EVP_sha, EVP_sha1, EVP_dss, EVP_dss1, EVP_mdc2,
139 EVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj \-
140 EVP digest routines
141 .SH "SYNOPSIS"
142 .IX Header "SYNOPSIS"
143 .Vb 1
144 \& #include <openssl/evp.h>
145 .Ve
146 .PP
147 .Vb 2
148 \& void EVP_MD_CTX_init(EVP_MD_CTX *ctx);
149 \& EVP_MD_CTX *EVP_MD_CTX_create(void);
150 .Ve
151 .PP
152 .Vb 4
153 \& int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
154 \& int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
155 \& int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md,
156 \& unsigned int *s);
157 .Ve
158 .PP
159 .Vb 2
160 \& int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);
161 \& void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);
162 .Ve
163 .PP
164 .Vb 1
165 \& int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in);
166 .Ve
167 .PP
168 .Vb 3
169 \& int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
170 \& int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md,
171 \& unsigned int *s);
172 .Ve
173 .PP
174 .Vb 1
175 \& int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in);
176 .Ve
177 .PP
178 .Vb 1
179 \& #define EVP_MAX_MD_SIZE (16+20) /* The SSLv3 md5+sha1 type */
180 .Ve
181 .PP
182 .Vb 4
183 \& #define EVP_MD_type(e) ((e)->type)
184 \& #define EVP_MD_pkey_type(e) ((e)->pkey_type)
185 \& #define EVP_MD_size(e) ((e)->md_size)
186 \& #define EVP_MD_block_size(e) ((e)->block_size)
187 .Ve
188 .PP
189 .Vb 4
190 \& #define EVP_MD_CTX_md(e) (e)->digest)
191 \& #define EVP_MD_CTX_size(e) EVP_MD_size((e)->digest)
192 \& #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest)
193 \& #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest)
194 .Ve
195 .PP
196 .Vb 9
197 \& const EVP_MD *EVP_md_null(void);
198 \& const EVP_MD *EVP_md2(void);
199 \& const EVP_MD *EVP_md5(void);
200 \& const EVP_MD *EVP_sha(void);
201 \& const EVP_MD *EVP_sha1(void);
202 \& const EVP_MD *EVP_dss(void);
203 \& const EVP_MD *EVP_dss1(void);
204 \& const EVP_MD *EVP_mdc2(void);
205 \& const EVP_MD *EVP_ripemd160(void);
206 .Ve
207 .PP
208 .Vb 3
209 \& const EVP_MD *EVP_get_digestbyname(const char *name);
210 \& #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a))
211 \& #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a))
212 .Ve
213 .SH "DESCRIPTION"
214 .IX Header "DESCRIPTION"
215 The \s-1EVP\s0 digest routines are a high level interface to message digests.
216 .PP
217 \&\fIEVP_MD_CTX_init()\fR initializes digest contet \fBctx\fR.
218 .PP
219 \&\fIEVP_MD_CTX_create()\fR allocates, initializes and returns a digest contet.
220 .PP
221 \&\fIEVP_DigestInit_ex()\fR sets up digest context \fBctx\fR to use a digest
222 \&\fBtype\fR from \s-1ENGINE\s0 \fBimpl\fR. \fBctx\fR must be initialized before calling this
223 function. \fBtype\fR will typically be supplied by a functionsuch as \fIEVP_sha1()\fR.
224 If \fBimpl\fR is \s-1NULL\s0 then the default implementation of digest \fBtype\fR is used.
225 .PP
226 \&\fIEVP_DigestUpdate()\fR hashes \fBcnt\fR bytes of data at \fBd\fR into the
227 digest context \fBctx\fR. This function can be called several times on the
228 same \fBctx\fR to hash additional data.
229 .PP
230 \&\fIEVP_DigestFinal_ex()\fR retrieves the digest value from \fBctx\fR and places
231 it in \fBmd\fR. If the \fBs\fR parameter is not \s-1NULL\s0 then the number of
232 bytes of data written (i.e. the length of the digest) will be written
233 to the integer at \fBs\fR, at most \fB\s-1EVP_MAX_MD_SIZE\s0\fR bytes will be written.
234 After calling \fIEVP_DigestFinal_ex()\fR no additional calls to \fIEVP_DigestUpdate()\fR
235 can be made, but \fIEVP_DigestInit_ex()\fR can be called to initialize a new
236 digest operation.
237 .PP
238 \&\fIEVP_MD_CTX_cleanup()\fR cleans up digest context \fBctx\fR, it should be called
239 after a digest context is no longer needed.
240 .PP
241 \&\fIEVP_MD_CTX_destroy()\fR cleans up digest context \fBctx\fR and frees up the
242 space allocated to it, it should be called only on a context created
243 using \fIEVP_MD_CTX_create()\fR.
244 .PP
245 \&\fIEVP_MD_CTX_copy_ex()\fR can be used to copy the message digest state from
246 \&\fBin\fR to \fBout\fR. This is useful if large amounts of data are to be
247 hashed which only differ in the last few bytes. \fBout\fR must be initialized
248 before calling this function.
249 .PP
250 \&\fIEVP_DigestInit()\fR behaves in the same way as \fIEVP_DigestInit_ex()\fR except
251 the passed context \fBctx\fR does not have to be initialized, and it always
252 uses the default digest implementation.
253 .PP
254 \&\fIEVP_DigestFinal()\fR is similar to \fIEVP_DigestFinal_ex()\fR except the digest
255 contet \fBctx\fR is automatically cleaned up.
256 .PP
257 \&\fIEVP_MD_CTX_copy()\fR is similar to \fIEVP_MD_CTX_copy_ex()\fR except the destination
258 \&\fBout\fR does not have to be initialized.
259 .PP
260 \&\fIEVP_MD_size()\fR and \fIEVP_MD_CTX_size()\fR return the size of the message digest
261 when passed an \fB\s-1EVP_MD\s0\fR or an \fB\s-1EVP_MD_CTX\s0\fR structure, i.e. the size of the
262 hash.
263 .PP
264 \&\fIEVP_MD_block_size()\fR and \fIEVP_MD_CTX_block_size()\fR return the block size of the
265 message digest when passed an \fB\s-1EVP_MD\s0\fR or an \fB\s-1EVP_MD_CTX\s0\fR structure.
266 .PP
267 \&\fIEVP_MD_type()\fR and \fIEVP_MD_CTX_type()\fR return the \s-1NID\s0 of the \s-1OBJECT\s0 \s-1IDENTIFIER\s0
268 representing the given message digest when passed an \fB\s-1EVP_MD\s0\fR structure.
269 For example EVP_MD_type(\fIEVP_sha1()\fR) returns \fBNID_sha1\fR. This function is
270 normally used when setting \s-1ASN1\s0 OIDs.
271 .PP
272 \&\fIEVP_MD_CTX_md()\fR returns the \fB\s-1EVP_MD\s0\fR structure corresponding to the passed
273 \&\fB\s-1EVP_MD_CTX\s0\fR.
274 .PP
275 \&\fIEVP_MD_pkey_type()\fR returns the \s-1NID\s0 of the public key signing algorithm associated
276 with this digest. For example \fIEVP_sha1()\fR is associated with \s-1RSA\s0 so this will
277 return \fBNID_sha1WithRSAEncryption\fR. This \*(L"link\*(R" between digests and signature
278 algorithms may not be retained in future versions of OpenSSL.
279 .PP
280 \&\fIEVP_md2()\fR, \fIEVP_md5()\fR, \fIEVP_sha()\fR, \fIEVP_sha1()\fR, \fIEVP_mdc2()\fR and \fIEVP_ripemd160()\fR
281 return \fB\s-1EVP_MD\s0\fR structures for the \s-1MD2\s0, \s-1MD5\s0, \s-1SHA\s0, \s-1SHA1\s0, \s-1MDC2\s0 and \s-1RIPEMD160\s0 digest
282 algorithms respectively. The associated signature algorithm is \s-1RSA\s0 in each case.
283 .PP
284 \&\fIEVP_dss()\fR and \fIEVP_dss1()\fR return \fB\s-1EVP_MD\s0\fR structures for \s-1SHA\s0 and \s-1SHA1\s0 digest
285 algorithms but using \s-1DSS\s0 (\s-1DSA\s0) for the signature algorithm.
286 .PP
287 \&\fIEVP_md_null()\fR is a \*(L"null\*(R" message digest that does nothing: i.e. the hash it
288 returns is of zero length.
289 .PP
290 \&\fIEVP_get_digestbyname()\fR, \fIEVP_get_digestbynid()\fR and \fIEVP_get_digestbyobj()\fR
291 return an \fB\s-1EVP_MD\s0\fR structure when passed a digest name, a digest \s-1NID\s0 or
292 an \s-1ASN1_OBJECT\s0 structure respectively. The digest table must be initialized
293 using, for example, \fIOpenSSL_add_all_digests()\fR for these functions to work.
294 .SH "RETURN VALUES"
295 .IX Header "RETURN VALUES"
296 \&\fIEVP_DigestInit_ex()\fR, \fIEVP_DigestUpdate()\fR and \fIEVP_DigestFinal_ex()\fR return 1 for
297 success and 0 for failure.
298 .PP
299 \&\fIEVP_MD_CTX_copy_ex()\fR returns 1 if successful or 0 for failure.
300 .PP
301 \&\fIEVP_MD_type()\fR, \fIEVP_MD_pkey_type()\fR and \fIEVP_MD_type()\fR return the \s-1NID\s0 of the
302 corresponding \s-1OBJECT\s0 \s-1IDENTIFIER\s0 or NID_undef if none exists.
303 .PP
304 \&\fIEVP_MD_size()\fR, \fIEVP_MD_block_size()\fR, EVP_MD_CTX_size(e), \fIEVP_MD_size()\fR,
305 \&\fIEVP_MD_CTX_block_size()\fR and \fIEVP_MD_block_size()\fR return the digest or block
306 size in bytes.
307 .PP
308 \&\fIEVP_md_null()\fR, \fIEVP_md2()\fR, \fIEVP_md5()\fR, \fIEVP_sha()\fR, \fIEVP_sha1()\fR, \fIEVP_dss()\fR,
309 \&\fIEVP_dss1()\fR, \fIEVP_mdc2()\fR and \fIEVP_ripemd160()\fR return pointers to the
310 corresponding \s-1EVP_MD\s0 structures.
311 .PP
312 \&\fIEVP_get_digestbyname()\fR, \fIEVP_get_digestbynid()\fR and \fIEVP_get_digestbyobj()\fR
313 return either an \fB\s-1EVP_MD\s0\fR structure or \s-1NULL\s0 if an error occurs.
314 .SH "NOTES"
315 .IX Header "NOTES"
316 The \fB\s-1EVP\s0\fR interface to message digests should almost always be used in
317 preference to the low level interfaces. This is because the code then becomes
318 transparent to the digest used and much more flexible.
319 .PP
320 \&\s-1SHA1\s0 is the digest of choice for new applications. The other digest algorithms
321 are still in common use.
322 .PP
323 For most applications the \fBimpl\fR parameter to \fIEVP_DigestInit_ex()\fR will be
324 set to \s-1NULL\s0 to use the default digest implementation.
325 .PP
326 The functions \fIEVP_DigestInit()\fR, \fIEVP_DigestFinal()\fR and \fIEVP_MD_CTX_copy()\fR are
327 obsolete but are retained to maintain compatibility with existing code. New
328 applications should use \fIEVP_DigestInit_ex()\fR, \fIEVP_DigestFinal_ex()\fR and
329 \&\fIEVP_MD_CTX_copy_ex()\fR because they can efficiently reuse a digest context
330 instead of initializing and cleaning it up on each call and allow non default
331 implementations of digests to be specified.
332 .PP
333 In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use
334 memory leaks will occur.
335 .SH "EXAMPLE"
336 .IX Header "EXAMPLE"
337 This example digests the data \*(L"Test Message\en\*(R" and \*(L"Hello World\en\*(R", using the
338 digest name passed on the command line.
339 .PP
340 .Vb 2
341 \& #include <stdio.h>
342 \& #include <openssl/evp.h>
343 .Ve
344 .PP
345 .Vb 8
346 \& main(int argc, char *argv[])
347 \& {
348 \& EVP_MD_CTX mdctx;
349 \& const EVP_MD *md;
350 \& char mess1[] = "Test Message\en";
351 \& char mess2[] = "Hello World\en";
352 \& unsigned char md_value[EVP_MAX_MD_SIZE];
353 \& int md_len, i;
354 .Ve
355 .PP
356 .Vb 1
357 \& OpenSSL_add_all_digests();
358 .Ve
359 .PP
360 .Vb 4
361 \& if(!argv[1]) {
362 \& printf("Usage: mdtest digestname\en");
363 \& exit(1);
364 \& }
365 .Ve
366 .PP
367 .Vb 1
368 \& md = EVP_get_digestbyname(argv[1]);
369 .Ve
370 .PP
371 .Vb 4
372 \& if(!md) {
373 \& printf("Unknown message digest %s\en", argv[1]);
374 \& exit(1);
375 \& }
376 .Ve
377 .PP
378 .Vb 6
379 \& EVP_MD_CTX_init(&mdctx);
380 \& EVP_DigestInit_ex(&mdctx, md, NULL);
381 \& EVP_DigestUpdate(&mdctx, mess1, strlen(mess1));
382 \& EVP_DigestUpdate(&mdctx, mess2, strlen(mess2));
383 \& EVP_DigestFinal_ex(&mdctx, md_value, &md_len);
384 \& EVP_MD_CTX_cleanup(&mdctx);
385 .Ve
386 .PP
387 .Vb 4
388 \& printf("Digest is: ");
389 \& for(i = 0; i < md_len; i++) printf("%02x", md_value[i]);
390 \& printf("\en");
391 \& }
392 .Ve
393 .SH "BUGS"
394 .IX Header "BUGS"
395 The link between digests and signing algorithms results in a situation where
396 \&\fIEVP_sha1()\fR must be used with \s-1RSA\s0 and \fIEVP_dss1()\fR must be used with \s-1DSS\s0
397 even though they are identical digests.
398 .SH "SEE ALSO"
399 .IX Header "SEE ALSO"
400 \&\fIevp\fR\|(3), \fIhmac\fR\|(3), \fImd2\fR\|(3),
401 \&\fImd5\fR\|(3), \fImdc2\fR\|(3), \fIripemd\fR\|(3),
402 \&\fIsha\fR\|(3), \fIdgst\fR\|(1)
403 .SH "HISTORY"
404 .IX Header "HISTORY"
405 \&\fIEVP_DigestInit()\fR, \fIEVP_DigestUpdate()\fR and \fIEVP_DigestFinal()\fR are
406 available in all versions of SSLeay and OpenSSL.
407 .PP
408 \&\fIEVP_MD_CTX_init()\fR, \fIEVP_MD_CTX_create()\fR, \fIEVP_MD_CTX_copy_ex()\fR,
409 \&\fIEVP_MD_CTX_cleanup()\fR, \fIEVP_MD_CTX_destroy()\fR, \fIEVP_DigestInit_ex()\fR
410 and \fIEVP_DigestFinal_ex()\fR were added in OpenSSL 0.9.7.
411 .PP
412 \&\fIEVP_md_null()\fR, \fIEVP_md2()\fR, \fIEVP_md5()\fR, \fIEVP_sha()\fR, \fIEVP_sha1()\fR,
413 \&\fIEVP_dss()\fR, \fIEVP_dss1()\fR, \fIEVP_mdc2()\fR and \fIEVP_ripemd160()\fR were
414 changed to return truely const \s-1EVP_MD\s0 * in OpenSSL 0.9.7.