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.\" ========================================================================
.\"
.IX Title "DSA_METH_NEW 3"
.TH DSA_METH_NEW 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
DSA_meth_new, DSA_meth_free, DSA_meth_dup, DSA_meth_get0_name, DSA_meth_set1_name, DSA_meth_get_flags, DSA_meth_set_flags, DSA_meth_get0_app_data, DSA_meth_set0_app_data, DSA_meth_get_sign, DSA_meth_set_sign, DSA_meth_get_sign_setup, DSA_meth_set_sign_setup, DSA_meth_get_verify, DSA_meth_set_verify, DSA_meth_get_mod_exp, DSA_meth_set_mod_exp, DSA_meth_get_bn_mod_exp, DSA_meth_set_bn_mod_exp, DSA_meth_get_init, DSA_meth_set_init, DSA_meth_get_finish, DSA_meth_set_finish, DSA_meth_get_paramgen, DSA_meth_set_paramgen, DSA_meth_get_keygen, DSA_meth_set_keygen \- Routines to build up DSA methods
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/dsa.h>
\&
\& DSA_METHOD *DSA_meth_new(const char *name, int flags);
\&
\& void DSA_meth_free(DSA_METHOD *dsam);
\&
\& DSA_METHOD *DSA_meth_dup(const DSA_METHOD *meth);
\&
\& const char *DSA_meth_get0_name(const DSA_METHOD *dsam);
\& int DSA_meth_set1_name(DSA_METHOD *dsam, const char *name);
\&
\& int DSA_meth_get_flags(const DSA_METHOD *dsam);
\& int DSA_meth_set_flags(DSA_METHOD *dsam, int flags);
\&
\& void *DSA_meth_get0_app_data(const DSA_METHOD *dsam);
\& int DSA_meth_set0_app_data(DSA_METHOD *dsam, void *app_data);
\&
\& DSA_SIG *(*DSA_meth_get_sign(const DSA_METHOD *dsam))(const unsigned char *,
\&                                                       int, DSA *);
\& int DSA_meth_set_sign(DSA_METHOD *dsam, DSA_SIG *(*sign)(const unsigned char *,
\&                                                          int, DSA *));
\&
\& int (*DSA_meth_get_sign_setup(const DSA_METHOD *dsam))(DSA *, BN_CTX *,$
\&                                                        BIGNUM **, BIGNUM **);
\& int DSA_meth_set_sign_setup(DSA_METHOD *dsam, int (*sign_setup)(DSA *, BN_CTX *,
\&                                                                 BIGNUM **, BIGNUM **));
\&
\& int (*DSA_meth_get_verify(const DSA_METHOD *dsam))(const unsigned char *,
\&                                                    int, DSA_SIG *, DSA *);
\& int DSA_meth_set_verify(DSA_METHOD *dsam, int (*verify)(const unsigned char *,
\&                                                         int, DSA_SIG *, DSA *));
\&
\& int (*DSA_meth_get_mod_exp(const DSA_METHOD *dsam))(DSA *dsa, BIGNUM *rr, BIGNUM *a1,
\&                                                     BIGNUM *p1, BIGNUM *a2, BIGNUM *p2,
\&                                                     BIGNUM *m, BN_CTX *ctx,
\&                                                     BN_MONT_CTX *in_mont);
\& int DSA_meth_set_mod_exp(DSA_METHOD *dsam, int (*mod_exp)(DSA *dsa, BIGNUM *rr,
\&                                                           BIGNUM *a1, BIGNUM *p1,
\&                                                           BIGNUM *a2, BIGNUM *p2,
\&                                                           BIGNUM *m, BN_CTX *ctx,
\&                                                           BN_MONT_CTX *mont));
\&
\& int (*DSA_meth_get_bn_mod_exp(const DSA_METHOD *dsam))(DSA *dsa, BIGNUM *r, BIGNUM *a,
\&                                                        const BIGNUM *p, const BIGNUM *m,
\&                                                        BN_CTX *ctx, BN_MONT_CTX *mont);
\& int DSA_meth_set_bn_mod_exp(DSA_METHOD *dsam, int (*bn_mod_exp)(DSA *dsa,
\&                                                                 BIGNUM *r,
\&                                                                 BIGNUM *a,
\&                                                                 const BIGNUM *p,
\&                                                                 const BIGNUM *m,
\&                                                                 BN_CTX *ctx,
\&                                                                 BN_MONT_CTX *mont));
\&
\& int (*DSA_meth_get_init(const DSA_METHOD *dsam))(DSA *);
\& int DSA_meth_set_init(DSA_METHOD *dsam, int (*init)(DSA *));
\&
\& int (*DSA_meth_get_finish(const DSA_METHOD *dsam))(DSA *);
\& int DSA_meth_set_finish(DSA_METHOD *dsam, int (*finish)(DSA *));
\&
\& int (*DSA_meth_get_paramgen(const DSA_METHOD *dsam))(DSA *, int,
\&                                                      const unsigned char *,
\&                                                      int, int *, unsigned long *,
\&                                                      BN_GENCB *);
\& int DSA_meth_set_paramgen(DSA_METHOD *dsam,
\&                           int (*paramgen)(DSA *, int, const unsigned char *,
\&                                           int, int *, unsigned long *, BN_GENCB *));
\&
\& int (*DSA_meth_get_keygen(const DSA_METHOD *dsam))(DSA *);
\& int DSA_meth_set_keygen(DSA_METHOD *dsam, int (*keygen)(DSA *));
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fB\s-1DSA_METHOD\s0\fR type is a structure used for the provision of custom \s-1DSA\s0
implementations. It provides a set of functions used by OpenSSL for the
implementation of the various \s-1DSA\s0 capabilities. See the dsa page for more
information.
.PP
\&\fBDSA_meth_new()\fR creates a new \fB\s-1DSA_METHOD\s0\fR structure. It should be given a
unique \fBname\fR and a set of \fBflags\fR. The \fBname\fR should be a \s-1NULL\s0 terminated
string, which will be duplicated and stored in the \fB\s-1DSA_METHOD\s0\fR object. It is
the callers responsibility to free the original string. The flags will be used
during the construction of a new \fB\s-1DSA\s0\fR object based on this \fB\s-1DSA_METHOD\s0\fR. Any
new \fB\s-1DSA\s0\fR object will have those flags set by default.
.PP
\&\fBDSA_meth_dup()\fR creates a duplicate copy of the \fB\s-1DSA_METHOD\s0\fR object passed as a
parameter. This might be useful for creating a new \fB\s-1DSA_METHOD\s0\fR based on an
existing one, but with some differences.
.PP
\&\fBDSA_meth_free()\fR destroys a \fB\s-1DSA_METHOD\s0\fR structure and frees up any memory
associated with it.
.PP
\&\fBDSA_meth_get0_name()\fR will return a pointer to the name of this \s-1DSA_METHOD.\s0 This
is a pointer to the internal name string and so should not be freed by the
caller. \fBDSA_meth_set1_name()\fR sets the name of the \s-1DSA_METHOD\s0 to \fBname\fR. The
string is duplicated and the copy is stored in the \s-1DSA_METHOD\s0 structure, so the
caller remains responsible for freeing the memory associated with the name.
.PP
\&\fBDSA_meth_get_flags()\fR returns the current value of the flags associated with this
\&\s-1DSA_METHOD.\s0 \fBDSA_meth_set_flags()\fR provides the ability to set these flags.
.PP
The functions \fBDSA_meth_get0_app_data()\fR and \fBDSA_meth_set0_app_data()\fR provide the
ability to associate implementation specific data with the \s-1DSA_METHOD.\s0 It is
the application's responsibility to free this data before the \s-1DSA_METHOD\s0 is
freed via a call to \fBDSA_meth_free()\fR.
.PP
\&\fBDSA_meth_get_sign()\fR and \fBDSA_meth_set_sign()\fR get and set the function used for
creating a \s-1DSA\s0 signature respectively. This function will be
called in response to the application calling \fBDSA_do_sign()\fR (or \fBDSA_sign()\fR). The
parameters for the function have the same meaning as for \fBDSA_do_sign()\fR.
.PP
\&\fBDSA_meth_get_sign_setup()\fR and \fBDSA_meth_set_sign_setup()\fR get and set the function
used for precalculating the \s-1DSA\s0 signature values \fBk^\-1\fR and \fBr\fR. This function
will be called in response to the application calling \fBDSA_sign_setup()\fR. The
parameters for the function have the same meaning as for \fBDSA_sign_setup()\fR.
.PP
\&\fBDSA_meth_get_verify()\fR and \fBDSA_meth_set_verify()\fR get and set the function used
for verifying a \s-1DSA\s0 signature respectively. This function will be called in
response to the application calling \fBDSA_do_verify()\fR (or \fBDSA_verify()\fR). The
parameters for the function have the same meaning as for \fBDSA_do_verify()\fR.
.PP
\&\fBDSA_meth_get_mod_exp()\fR and \fBDSA_meth_set_mod_exp()\fR get and set the function used
for computing the following value:
.PP
.Vb 1
\& rr = a1^p1 * a2^p2 mod m
.Ve
.PP
This function will be called by the default OpenSSL method during verification
of a \s-1DSA\s0 signature. The result is stored in the \fBrr\fR parameter. This function
may be \s-1NULL.\s0
.PP
\&\fBDSA_meth_get_bn_mod_exp()\fR and \fBDSA_meth_set_bn_mod_exp()\fR get and set the function
used for computing the following value:
.PP
.Vb 1
\& r = a ^ p mod m
.Ve
.PP
This function will be called by the default OpenSSL function for
\&\fBDSA_sign_setup()\fR. The result is stored in the \fBr\fR parameter. This function
may be \s-1NULL.\s0
.PP
\&\fBDSA_meth_get_init()\fR and \fBDSA_meth_set_init()\fR get and set the function used
for creating a new \s-1DSA\s0 instance respectively. This function will be
called in response to the application calling \fBDSA_new()\fR (if the current default
\&\s-1DSA_METHOD\s0 is this one) or \fBDSA_new_method()\fR. The \fBDSA_new()\fR and \fBDSA_new_method()\fR
functions will allocate the memory for the new \s-1DSA\s0 object, and a pointer to this
newly allocated structure will be passed as a parameter to the function. This
function may be \s-1NULL.\s0
.PP
\&\fBDSA_meth_get_finish()\fR and \fBDSA_meth_set_finish()\fR get and set the function used
for destroying an instance of a \s-1DSA\s0 object respectively. This function will be
called in response to the application calling \fBDSA_free()\fR. A pointer to the \s-1DSA\s0
to be destroyed is passed as a parameter. The destroy function should be used
for \s-1DSA\s0 implementation specific clean up. The memory for the \s-1DSA\s0 itself should
not be freed by this function. This function may be \s-1NULL.\s0
.PP
\&\fBDSA_meth_get_paramgen()\fR and \fBDSA_meth_set_paramgen()\fR get and set the function
used for generating \s-1DSA\s0 parameters respectively. This function will be called in
response to the application calling \fBDSA_generate_parameters_ex()\fR (or
\&\fBDSA_generate_parameters()\fR). The parameters for the function have the same
meaning as for \fBDSA_generate_parameters_ex()\fR.
.PP
\&\fBDSA_meth_get_keygen()\fR and \fBDSA_meth_set_keygen()\fR get and set the function
used for generating a new \s-1DSA\s0 key pair respectively. This function will be
called in response to the application calling \fBDSA_generate_key()\fR. The parameter
for the function has the same meaning as for \fBDSA_generate_key()\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBDSA_meth_new()\fR and \fBDSA_meth_dup()\fR return the newly allocated \s-1DSA_METHOD\s0 object
or \s-1NULL\s0 on failure.
.PP
\&\fBDSA_meth_get0_name()\fR and \fBDSA_meth_get_flags()\fR return the name and flags
associated with the \s-1DSA_METHOD\s0 respectively.
.PP
All other DSA_meth_get_*() functions return the appropriate function pointer
that has been set in the \s-1DSA_METHOD,\s0 or \s-1NULL\s0 if no such pointer has yet been
set.
.PP
\&\fBDSA_meth_set1_name()\fR and all DSA_meth_set_*() functions return 1 on success or
0 on failure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBDSA_new\fR\|(3), \fBDSA_new\fR\|(3), \fBDSA_generate_parameters\fR\|(3), \fBDSA_generate_key\fR\|(3),
\&\fBDSA_dup_DH\fR\|(3), \fBDSA_do_sign\fR\|(3), \fBDSA_set_method\fR\|(3), \fBDSA_SIG_new\fR\|(3),
\&\fBDSA_sign\fR\|(3), \fBDSA_size\fR\|(3), \fBDSA_get0_pqg\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The functions described here were added in OpenSSL 1.1.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2016\-2018 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.