3.\"
4.\" Standard preamble:
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37.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used
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39.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<>
40.tr \(*W-|\(bv\*(Tr
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58.\"
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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
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137.rm #[ #] #H #V #F C
138.\" ======================================================================
139.\"
140.IX Title "DSA_set_method 3"
| 3.\"
4.\" Standard preamble:
5.\" ======================================================================
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9.ne 5
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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'
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45. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
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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
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69.\}
70.\"
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72.\" makes way too many mistakes in technical documents.
73.hy 0
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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.
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137.rm #[ #] #H #V #F C
138.\" ======================================================================
139.\"
140.IX Title "DSA_set_method 3"
|
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.
| 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.
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