Initial import from FreeBSD RELENG_4:
[dragonfly.git] / secure / lib / libcrypto / man / DSA_set_method.3
CommitLineData
984263bc
MD
1.\" Automatically generated by Pod::Man version 1.15
2.\" Wed Feb 19 16:42:51 2003
3.\"
4.\" Standard preamble:
5.\" ======================================================================
6.de Sh \" Subsection heading
7.br
8.if t .Sp
9.ne 5
10.PP
11\fB\\$1\fR
12.PP
13..
14.de Sp \" Vertical space (when we can't use .PP)
15.if t .sp .5v
16.if n .sp
17..
18.de Ip \" List item
19.br
20.ie \\n(.$>=3 .ne \\$3
21.el .ne 3
22.IP "\\$1" \\$2
23..
24.de Vb \" Begin verbatim text
25.ft CW
26.nf
27.ne \\$1
28..
29.de Ve \" End verbatim text
30.ft R
31
32.fi
33..
34.\" Set up some character translations and predefined strings. \*(-- will
35.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
36.\" double quote, and \*(R" will give a right double quote. | will give a
37.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used
38.\" to do unbreakable dashes and therefore won't be available. \*(C` and
39.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<>
40.tr \(*W-|\(bv\*(Tr
41.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
42.ie n \{\
43. ds -- \(*W-
44. ds PI pi
45. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
46. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
47. ds L" ""
48. ds R" ""
49. ds C` ""
50. ds C' ""
51'br\}
52.el\{\
53. ds -- \|\(em\|
54. ds PI \(*p
55. ds L" ``
56. ds R" ''
57'br\}
58.\"
59.\" If the F register is turned on, we'll generate index entries on stderr
60.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
61.\" index entries marked with X<> in POD. Of course, you'll have to process
62.\" the output yourself in some meaningful fashion.
63.if \nF \{\
64. de IX
65. tm Index:\\$1\t\\n%\t"\\$2"
66..
67. nr % 0
68. rr F
69.\}
70.\"
71.\" For nroff, turn off justification. Always turn off hyphenation; it
72.\" makes way too many mistakes in technical documents.
73.hy 0
74.if n .na
75.\"
76.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
77.\" Fear. Run. Save yourself. No user-serviceable parts.
78.bd B 3
79. \" fudge factors for nroff and troff
80.if n \{\
81. ds #H 0
82. ds #V .8m
83. ds #F .3m
84. ds #[ \f1
85. ds #] \fP
86.\}
87.if t \{\
88. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
89. ds #V .6m
90. ds #F 0
91. ds #[ \&
92. ds #] \&
93.\}
94. \" simple accents for nroff and troff
95.if n \{\
96. ds ' \&
97. ds ` \&
98. ds ^ \&
99. ds , \&
100. ds ~ ~
101. ds /
102.\}
103.if t \{\
104. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
105. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
106. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
107. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
108. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
109. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
110.\}
111. \" troff and (daisy-wheel) nroff accents
112.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
113.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
114.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
115.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
116.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
117.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
118.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
119.ds ae a\h'-(\w'a'u*4/10)'e
120.ds Ae A\h'-(\w'A'u*4/10)'E
121. \" corrections for vroff
122.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
123.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
124. \" for low resolution devices (crt and lpr)
125.if \n(.H>23 .if \n(.V>19 \
126\{\
127. ds : e
128. ds 8 ss
129. ds o a
130. ds d- d\h'-1'\(ga
131. ds D- D\h'-1'\(hy
132. ds th \o'bp'
133. ds Th \o'LP'
134. ds ae ae
135. ds Ae AE
136.\}
137.rm #[ #] #H #V #F C
138.\" ======================================================================
139.\"
140.IX Title "DSA_set_method 3"
141.TH DSA_set_method 3 "0.9.7a" "2003-02-19" "OpenSSL"
142.UC
143.SH "NAME"
144DSA_set_default_method, DSA_get_default_method,
145DSA_set_method, DSA_new_method, DSA_OpenSSL \- select \s-1DSA\s0 method
146.SH "SYNOPSIS"
147.IX Header "SYNOPSIS"
148.Vb 2
149\& #include <openssl/dsa.h>
150\& #include <openssl/engine.h>
151.Ve
152.Vb 1
153\& void DSA_set_default_method(const DSA_METHOD *meth);
154.Ve
155.Vb 1
156\& const DSA_METHOD *DSA_get_default_method(void);
157.Ve
158.Vb 1
159\& int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
160.Ve
161.Vb 1
162\& DSA *DSA_new_method(ENGINE *engine);
163.Ve
164.Vb 1
165\& DSA_METHOD *DSA_OpenSSL(void);
166.Ve
167.SH "DESCRIPTION"
168.IX Header "DESCRIPTION"
169A \fB\s-1DSA_METHOD\s0\fR specifies the functions that OpenSSL uses for \s-1DSA\s0
170operations. By modifying the method, alternative implementations
171such as hardware accelerators may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for
172important information about how these \s-1DSA\s0 \s-1API\s0 functions are affected by the use
173of \fB\s-1ENGINE\s0\fR \s-1API\s0 calls.
174.PP
175Initially, the default \s-1DSA_METHOD\s0 is the OpenSSL internal implementation,
176as returned by \fIDSA_OpenSSL()\fR.
177.PP
178\&\fIDSA_set_default_method()\fR makes \fBmeth\fR the default method for all \s-1DSA\s0
179structures created later. \fB\s-1NB\s0\fR: This is true only whilst no \s-1ENGINE\s0 has
180been set as a default for \s-1DSA\s0, so this function is no longer recommended.
181.PP
182\&\fIDSA_get_default_method()\fR returns a pointer to the current default
183\&\s-1DSA_METHOD\s0. However, the meaningfulness of this result is dependant on
184whether the \s-1ENGINE\s0 \s-1API\s0 is being used, so this function is no longer
185recommended.
186.PP
187\&\fIDSA_set_method()\fR selects \fBmeth\fR to perform all operations using the key
188\&\fBrsa\fR. This will replace the \s-1DSA_METHOD\s0 used by the \s-1DSA\s0 key and if the
189previous method was supplied by an \s-1ENGINE\s0, the handle to that \s-1ENGINE\s0 will
190be released during the change. It is possible to have \s-1DSA\s0 keys that only
191work with certain \s-1DSA_METHOD\s0 implementations (eg. from an \s-1ENGINE\s0 module
192that supports embedded hardware-protected keys), and in such cases
193attempting to change the \s-1DSA_METHOD\s0 for the key can have unexpected
194results.
195.PP
196\&\fIDSA_new_method()\fR allocates and initializes a \s-1DSA\s0 structure so that \fBengine\fR
197will be used for the \s-1DSA\s0 operations. If \fBengine\fR is \s-1NULL\s0, the default engine
198for \s-1DSA\s0 operations is used, and if no default \s-1ENGINE\s0 is set, the \s-1DSA_METHOD\s0
199controlled by \fIDSA_set_default_method()\fR is used.
200.SH "THE DSA_METHOD STRUCTURE"
201.IX Header "THE DSA_METHOD STRUCTURE"
202struct
203 {
204 /* name of the implementation */
205 const char *name;
206.PP
207.Vb 3
208\& /* sign */
209\& DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
210\& DSA *dsa);
211.Ve
212.Vb 3
213\& /* pre-compute k^-1 and r */
214\& int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
215\& BIGNUM **rp);
216.Ve
217.Vb 3
218\& /* verify */
219\& int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
220\& DSA_SIG *sig, DSA *dsa);
221.Ve
222.Vb 5
223\& /* compute rr = a1^p1 * a2^p2 mod m (May be NULL for some
224\& implementations) */
225\& int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
226\& BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
227\& BN_CTX *ctx, BN_MONT_CTX *in_mont);
228.Ve
229.Vb 4
230\& /* compute r = a ^ p mod m (May be NULL for some implementations) */
231\& int (*bn_mod_exp)(DSA *dsa, BIGNUM *r, BIGNUM *a,
232\& const BIGNUM *p, const BIGNUM *m,
233\& BN_CTX *ctx, BN_MONT_CTX *m_ctx);
234.Ve
235.Vb 2
236\& /* called at DSA_new */
237\& int (*init)(DSA *DSA);
238.Ve
239.Vb 2
240\& /* called at DSA_free */
241\& int (*finish)(DSA *DSA);
242.Ve
243.Vb 1
244\& int flags;
245.Ve
246.Vb 1
247\& char *app_data; /* ?? */
248.Ve
249.Vb 1
250\& } DSA_METHOD;
251.Ve
252.SH "RETURN VALUES"
253.IX Header "RETURN VALUES"
254\&\fIDSA_OpenSSL()\fR and \fIDSA_get_default_method()\fR return pointers to the respective
255\&\fB\s-1DSA_METHOD\s0\fRs.
256.PP
257\&\fIDSA_set_default_method()\fR returns no value.
258.PP
259\&\fIDSA_set_method()\fR returns non-zero if the provided \fBmeth\fR was successfully set as
260the method for \fBdsa\fR (including unloading the \s-1ENGINE\s0 handle if the previous
261method was supplied by an \s-1ENGINE\s0).
262.PP
263\&\fIDSA_new_method()\fR returns \s-1NULL\s0 and sets an error code that can be
264obtained by ERR_get_error(3) if the allocation
265fails. Otherwise it returns a pointer to the newly allocated structure.
266.SH "NOTES"
267.IX Header "NOTES"
268As of version 0.9.7, \s-1DSA_METHOD\s0 implementations are grouped together with other
269algorithmic APIs (eg. \s-1RSA_METHOD\s0, \s-1EVP_CIPHER\s0, etc) in \fB\s-1ENGINE\s0\fR modules. If a
270default \s-1ENGINE\s0 is specified for \s-1DSA\s0 functionality using an \s-1ENGINE\s0 \s-1API\s0 function,
271that will override any \s-1DSA\s0 defaults set using the \s-1DSA\s0 \s-1API\s0 (ie.
272\&\fIDSA_set_default_method()\fR). For this reason, the \s-1ENGINE\s0 \s-1API\s0 is the recommended way
273to control default implementations for use in \s-1DSA\s0 and other cryptographic
274algorithms.
275.SH "SEE ALSO"
276.IX Header "SEE ALSO"
277dsa(3), DSA_new(3)
278.SH "HISTORY"
279.IX Header "HISTORY"
280\&\fIDSA_set_default_method()\fR, \fIDSA_get_default_method()\fR, \fIDSA_set_method()\fR,
281\&\fIDSA_new_method()\fR and \fIDSA_OpenSSL()\fR were added in OpenSSL 0.9.4.
282.PP
283\&\fIDSA_set_default_openssl_method()\fR and \fIDSA_get_default_openssl_method()\fR replaced
284\&\fIDSA_set_default_method()\fR and \fIDSA_get_default_method()\fR respectively, and
285\&\fIDSA_set_method()\fR and \fIDSA_new_method()\fR were altered to use \fB\s-1ENGINE\s0\fRs rather than
286\&\fB\s-1DSA_METHOD\s0\fRs during development of the engine version of OpenSSL 0.9.6. For
2870.9.7, the handling of defaults in the \s-1ENGINE\s0 \s-1API\s0 was restructured so that this
288change was reversed, and behaviour of the other functions resembled more closely
289the previous behaviour. The behaviour of defaults in the \s-1ENGINE\s0 \s-1API\s0 now
290transparently overrides the behaviour of defaults in the \s-1DSA\s0 \s-1API\s0 without
291requiring changing these function prototypes.