1 .\" $OpenBSD: DSA_set_method.3,v 1.9 2018/04/18 01:09:01 schwarze Exp $
2 .\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
4 .\" This file was written by Ulf Moeller <ulf@openssl.org>.
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51 .Dd $Mdocdate: April 18 2018 $
55 .Nm DSA_set_default_method ,
56 .Nm DSA_get_default_method ,
64 .Fo DSA_set_default_method
65 .Fa "const DSA_METHOD *meth"
67 .Ft const DSA_METHOD *
68 .Fn DSA_get_default_method void
72 .Fa "const DSA_METHOD *meth"
83 object contains pointers to the functions used for DSA operations.
84 By default, the internal implementation returned by
87 By selecting another method, alternative implementations
88 such as hardware accelerators may be used.
90 .Fn DSA_set_default_method
93 as the default method for all
95 structures created later.
99 .Xr ENGINE_register_DSA 3
100 that can be successfully initialized, it overrides the default.
102 .Fn DSA_get_default_method
103 returns a pointer to the current default method,
104 even if it is actually overridded by an
110 to perform all operations using the key
114 used by the DSA key and if the previous method was supplied by an
118 It is possible to have DSA keys that only work with certain
120 implementations (e.g. from an
122 module that supports embedded hardware-protected keys),
123 and in such cases attempting to change the
125 for the key can have unexpected results.
128 allocates and initializes a
132 is used for the DSA operations.
137 .Xr ENGINE_get_default_DSA 3
141 the default method controlled by
142 .Fn DSA_set_default_method
147 structure is defined as follows:
151 /* name of the implementation */
155 DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
158 /* pre-compute k^-1 and r */
159 int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
163 int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
164 DSA_SIG *sig, DSA *dsa);
166 /* compute rr = a1^p1 * a2^p2 mod m (May be NULL for some
168 int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
169 BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
170 BN_CTX *ctx, BN_MONT_CTX *in_mont);
172 /* compute r = a ^ p mod m (May be NULL for some implementations) */
173 int (*bn_mod_exp)(DSA *dsa, BIGNUM *r, BIGNUM *a,
174 const BIGNUM *p, const BIGNUM *m,
175 BN_CTX *ctx, BN_MONT_CTX *m_ctx);
177 /* called at DSA_new */
178 int (*init)(DSA *DSA);
180 /* called at DSA_free */
181 int (*finish)(DSA *DSA);
185 char *app_data; /* ?? */
192 .Fn DSA_get_default_method
193 return pointers to the respective
197 returns 1 on success or 0 on failure.
198 Currently, it cannot fail.
203 and sets an error code that can be obtained by
205 if the allocation fails.
206 Otherwise it returns a pointer to the newly allocated structure.
210 .Xr ENGINE_get_default_DSA 3 ,
211 .Xr ENGINE_register_DSA 3 ,
212 .Xr ENGINE_set_default_DSA 3
214 .Fn DSA_set_default_method ,
215 .Fn DSA_get_default_method ,
220 first appeared in OpenSSL 0.9.5 and have been available since