summaryrefslogtreecommitdiffstats
path: root/secure/lib/libcrypto/man/DSA_set_method.3
blob: 736e8e4589dc0216415646097f65c9a1831b8b52 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
.    if \nF \{
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "DSA_set_method 3"
.TH DSA_set_method 3 "2016-09-22" "1.0.2i" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
DSA_set_default_method, DSA_get_default_method,
DSA_set_method, DSA_new_method, DSA_OpenSSL \- select DSA method
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& #include <openssl/dsa.h>
\& #include <openssl/engine.h>
\&
\& void DSA_set_default_method(const DSA_METHOD *meth);
\&
\& const DSA_METHOD *DSA_get_default_method(void);
\&
\& int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
\&
\& DSA *DSA_new_method(ENGINE *engine);
\&
\& DSA_METHOD *DSA_OpenSSL(void);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A \fB\s-1DSA_METHOD\s0\fR specifies the functions that OpenSSL uses for \s-1DSA\s0
operations. By modifying the method, alternative implementations
such as hardware accelerators may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for
important information about how these \s-1DSA API\s0 functions are affected by the use
of \fB\s-1ENGINE\s0\fR \s-1API\s0 calls.
.PP
Initially, the default \s-1DSA_METHOD\s0 is the OpenSSL internal implementation,
as returned by \fIDSA_OpenSSL()\fR.
.PP
\&\fIDSA_set_default_method()\fR makes \fBmeth\fR the default method for all \s-1DSA\s0
structures created later. \fB\s-1NB\s0\fR: This is true only whilst no \s-1ENGINE\s0 has
been set as a default for \s-1DSA,\s0 so this function is no longer recommended.
.PP
\&\fIDSA_get_default_method()\fR returns a pointer to the current default
\&\s-1DSA_METHOD.\s0 However, the meaningfulness of this result is dependent on
whether the \s-1ENGINE API\s0 is being used, so this function is no longer 
recommended.
.PP
\&\fIDSA_set_method()\fR selects \fBmeth\fR to perform all operations using the key
\&\fBrsa\fR. This will replace the \s-1DSA_METHOD\s0 used by the \s-1DSA\s0 key and if the
previous method was supplied by an \s-1ENGINE,\s0 the handle to that \s-1ENGINE\s0 will
be released during the change. It is possible to have \s-1DSA\s0 keys that only
work with certain \s-1DSA_METHOD\s0 implementations (eg. from an \s-1ENGINE\s0 module
that supports embedded hardware-protected keys), and in such cases
attempting to change the \s-1DSA_METHOD\s0 for the key can have unexpected
results.
.PP
\&\fIDSA_new_method()\fR allocates and initializes a \s-1DSA\s0 structure so that \fBengine\fR
will be used for the \s-1DSA\s0 operations. If \fBengine\fR is \s-1NULL,\s0 the default engine
for \s-1DSA\s0 operations is used, and if no default \s-1ENGINE\s0 is set, the \s-1DSA_METHOD\s0
controlled by \fIDSA_set_default_method()\fR is used.
.SH "THE DSA_METHOD STRUCTURE"
.IX Header "THE DSA_METHOD STRUCTURE"
struct
 {
     /* name of the implementation */
        const char *name;
.PP
.Vb 3
\&     /* sign */
\&        DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
\&                                 DSA *dsa);
\&
\&     /* pre\-compute k^\-1 and r */
\&        int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
\&                                 BIGNUM **rp);
\&
\&     /* verify */
\&        int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
\&                                 DSA_SIG *sig, DSA *dsa);
\&
\&     /* compute rr = a1^p1 * a2^p2 mod m (May be NULL for some
\&                                          implementations) */
\&        int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
\&                                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
\&                                 BN_CTX *ctx, BN_MONT_CTX *in_mont);
\&
\&     /* compute r = a ^ p mod m (May be NULL for some implementations) */
\&        int (*bn_mod_exp)(DSA *dsa, BIGNUM *r, BIGNUM *a,
\&                                 const BIGNUM *p, const BIGNUM *m,
\&                                 BN_CTX *ctx, BN_MONT_CTX *m_ctx);
\&
\&     /* called at DSA_new */
\&        int (*init)(DSA *DSA);
\&
\&     /* called at DSA_free */
\&        int (*finish)(DSA *DSA);
\&
\&        int flags;
\&
\&        char *app_data; /* ?? */
\&
\& } DSA_METHOD;
.Ve
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIDSA_OpenSSL()\fR and \fIDSA_get_default_method()\fR return pointers to the respective
\&\fB\s-1DSA_METHOD\s0\fRs.
.PP
\&\fIDSA_set_default_method()\fR returns no value.
.PP
\&\fIDSA_set_method()\fR returns non-zero if the provided \fBmeth\fR was successfully set as
the method for \fBdsa\fR (including unloading the \s-1ENGINE\s0 handle if the previous
method was supplied by an \s-1ENGINE\s0).
.PP
\&\fIDSA_new_method()\fR returns \s-1NULL\s0 and sets an error code that can be
obtained by \fIERR_get_error\fR\|(3) if the allocation
fails. Otherwise it returns a pointer to the newly allocated structure.
.SH "NOTES"
.IX Header "NOTES"
As of version 0.9.7, \s-1DSA_METHOD\s0 implementations are grouped together with other
algorithmic APIs (eg. \s-1RSA_METHOD, EVP_CIPHER,\s0 etc) in \fB\s-1ENGINE\s0\fR modules. If a
default \s-1ENGINE\s0 is specified for \s-1DSA\s0 functionality using an \s-1ENGINE API\s0 function,
that will override any \s-1DSA\s0 defaults set using the \s-1DSA API \s0(ie.
\&\fIDSA_set_default_method()\fR). For this reason, the \s-1ENGINE API\s0 is the recommended way
to control default implementations for use in \s-1DSA\s0 and other cryptographic
algorithms.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIdsa\fR\|(3), \fIDSA_new\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIDSA_set_default_method()\fR, \fIDSA_get_default_method()\fR, \fIDSA_set_method()\fR,
\&\fIDSA_new_method()\fR and \fIDSA_OpenSSL()\fR were added in OpenSSL 0.9.4.
.PP
\&\fIDSA_set_default_openssl_method()\fR and \fIDSA_get_default_openssl_method()\fR replaced
\&\fIDSA_set_default_method()\fR and \fIDSA_get_default_method()\fR respectively, and
\&\fIDSA_set_method()\fR and \fIDSA_new_method()\fR were altered to use \fB\s-1ENGINE\s0\fRs rather than
\&\fB\s-1DSA_METHOD\s0\fRs during development of the engine version of OpenSSL 0.9.6. For
0.9.7, the handling of defaults in the \s-1ENGINE API\s0 was restructured so that this
change was reversed, and behaviour of the other functions resembled more closely
the previous behaviour. The behaviour of defaults in the \s-1ENGINE API\s0 now
transparently overrides the behaviour of defaults in the \s-1DSA API\s0 without
requiring changing these function prototypes.
OpenPOWER on IntegriCloud