NetBSD/lib/libcrypto/man/DSA_set_method.3

.\"	$NetBSD: DSA_set_method.3,v 1.5 2001/04/12 10:45:37 itojun Exp $
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.\" ======================================================================
.\"
.IX Title "DSA_set_method 3"
.TH DSA_set_method 3 "0.9.6a" "2001-04-12" "OpenSSL"
.UC
.SH "NAME"
DSA_set_default_method, DSA_get_default_method, DSA_set_method,
DSA_new_method, DSA_OpenSSL \- select \s-1DSA\s0 method
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dsa.h>
.Ve
.Vb 1
\& void DSA_set_default_method(DSA_METHOD *meth);
.Ve
.Vb 1
\& DSA_METHOD *DSA_get_default_method(void);
.Ve
.Vb 1
\& DSA_METHOD *DSA_set_method(DSA *dsa, DSA_METHOD *meth);
.Ve
.Vb 1
\& DSA *DSA_new_method(DSA_METHOD *meth);
.Ve
.Vb 1
\& 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.
.PP
Initially, the default is to use the OpenSSL internal implementation.
\&\fIDSA_OpenSSL()\fR returns a pointer to that method.
.PP
\&\fIDSA_set_default_method()\fR makes \fBmeth\fR the default method for all \fB\s-1DSA\s0\fR
structures created later.
.PP
\&\fIDSA_get_default_method()\fR returns a pointer to the current default
method.
.PP
\&\fIDSA_set_method()\fR selects \fBmeth\fR for all operations using the structure \fBdsa\fR.
.PP
\&\fIDSA_new_method()\fR allocates and initializes a \fB\s-1DSA\s0\fR structure so that
\&\fBmethod\fR will be used for the \s-1DSA\s0 operations. If \fBmethod\fR is \fB\s-1NULL\s0\fR,
the default method 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);
.Ve
.Vb 3
\&     /* pre-compute k^-1 and r */
\&        int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
\&                                 BIGNUM **rp);
.Ve
.Vb 3
\&     /* verify */
\&        int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
\&                                 DSA_SIG *sig, DSA *dsa);
.Ve
.Vb 5
\&     /* 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);
.Ve
.Vb 4
\&     /* 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);
.Ve
.Vb 2
\&     /* called at DSA_new */
\&        int (*init)(DSA *DSA);
.Ve
.Vb 2
\&     /* called at DSA_free */
\&        int (*finish)(DSA *DSA);
.Ve
.Vb 1
\&        int flags;
.Ve
.Vb 1
\&        char *app_data; /* ?? */
.Ve
.Vb 1
\& } 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 a pointer to the \fB\s-1DSA_METHOD\s0\fR previously
associated with \fBdsa\fR.
.PP
\&\fIDSA_new_method()\fR returns \fB\s-1NULL\s0\fR and sets an error code that can be
obtained by ERR_get_error(3) if the allocation
fails. Otherwise it returns a pointer to the newly allocated
structure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
openssl_dsa(3), DSA_new(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.