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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
  <li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#HISTORY">HISTORY</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>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</p>

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<pre><code>#include &lt;openssl/dsa.h&gt;</code></pre>

<p>The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining <b>OPENSSL_API_COMPAT</b> with a suitable version value, see <a href="../man7/openssl_user_macros.html">openssl_user_macros(7)</a>:</p>

<pre><code>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 *));</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>All of the functions described on this page are deprecated. Applications and extension implementations should instead use the OSSL_PROVIDER APIs.</p>

<p>The <b>DSA_METHOD</b> type is a structure used for the provision of custom DSA implementations. It provides a set of functions used by OpenSSL for the implementation of the various DSA capabilities.</p>

<p>DSA_meth_new() creates a new <b>DSA_METHOD</b> structure. It should be given a unique <b>name</b> and a set of <b>flags</b>. The <b>name</b> should be a NULL terminated string, which will be duplicated and stored in the <b>DSA_METHOD</b> object. It is the callers responsibility to free the original string. The flags will be used during the construction of a new <b>DSA</b> object based on this <b>DSA_METHOD</b>. Any new <b>DSA</b> object will have those flags set by default.</p>

<p>DSA_meth_dup() creates a duplicate copy of the <b>DSA_METHOD</b> object passed as a parameter. This might be useful for creating a new <b>DSA_METHOD</b> based on an existing one, but with some differences.</p>

<p>DSA_meth_free() destroys a <b>DSA_METHOD</b> structure and frees up any memory associated with it. If the argument is NULL, nothing is done.</p>

<p>DSA_meth_get0_name() will return a pointer to the name of this DSA_METHOD. This is a pointer to the internal name string and so should not be freed by the caller. DSA_meth_set1_name() sets the name of the DSA_METHOD to <b>name</b>. The string is duplicated and the copy is stored in the DSA_METHOD structure, so the caller remains responsible for freeing the memory associated with the name.</p>

<p>DSA_meth_get_flags() returns the current value of the flags associated with this DSA_METHOD. DSA_meth_set_flags() provides the ability to set these flags.</p>

<p>The functions DSA_meth_get0_app_data() and DSA_meth_set0_app_data() provide the ability to associate implementation specific data with the DSA_METHOD. It is the application&#39;s responsibility to free this data before the DSA_METHOD is freed via a call to DSA_meth_free().</p>

<p>DSA_meth_get_sign() and DSA_meth_set_sign() get and set the function used for creating a DSA signature respectively. This function will be called in response to the application calling DSA_do_sign() (or DSA_sign()). The parameters for the function have the same meaning as for DSA_do_sign().</p>

<p>DSA_meth_get_sign_setup() and DSA_meth_set_sign_setup() get and set the function used for precalculating the DSA signature values <b>k^-1</b> and <b>r</b>. This function will be called in response to the application calling DSA_sign_setup(). The parameters for the function have the same meaning as for DSA_sign_setup().</p>

<p>DSA_meth_get_verify() and DSA_meth_set_verify() get and set the function used for verifying a DSA signature respectively. This function will be called in response to the application calling DSA_do_verify() (or DSA_verify()). The parameters for the function have the same meaning as for DSA_do_verify().</p>

<p>DSA_meth_get_mod_exp() and DSA_meth_set_mod_exp() get and set the function used for computing the following value:</p>

<pre><code>rr = a1^p1 * a2^p2 mod m</code></pre>

<p>This function will be called by the default OpenSSL method during verification of a DSA signature. The result is stored in the <b>rr</b> parameter. This function may be NULL.</p>

<p>DSA_meth_get_bn_mod_exp() and DSA_meth_set_bn_mod_exp() get and set the function used for computing the following value:</p>

<pre><code>r = a ^ p mod m</code></pre>

<p>This function will be called by the default OpenSSL function for DSA_sign_setup(). The result is stored in the <b>r</b> parameter. This function may be NULL.</p>

<p>DSA_meth_get_init() and DSA_meth_set_init() get and set the function used for creating a new DSA instance respectively. This function will be called in response to the application calling DSA_new() (if the current default DSA_METHOD is this one) or DSA_new_method(). The DSA_new() and DSA_new_method() functions will allocate the memory for the new DSA object, and a pointer to this newly allocated structure will be passed as a parameter to the function. This function may be NULL.</p>

<p>DSA_meth_get_finish() and DSA_meth_set_finish() get and set the function used for destroying an instance of a DSA object respectively. This function will be called in response to the application calling DSA_free(). A pointer to the DSA to be destroyed is passed as a parameter. The destroy function should be used for DSA implementation specific clean up. The memory for the DSA itself should not be freed by this function. This function may be NULL.</p>

<p>DSA_meth_get_paramgen() and DSA_meth_set_paramgen() get and set the function used for generating DSA parameters respectively. This function will be called in response to the application calling DSA_generate_parameters_ex() (or DSA_generate_parameters()). The parameters for the function have the same meaning as for DSA_generate_parameters_ex().</p>

<p>DSA_meth_get_keygen() and DSA_meth_set_keygen() get and set the function used for generating a new DSA key pair respectively. This function will be called in response to the application calling DSA_generate_key(). The parameter for the function has the same meaning as for DSA_generate_key().</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>DSA_meth_new() and DSA_meth_dup() return the newly allocated DSA_METHOD object or NULL on failure.</p>

<p>DSA_meth_get0_name() and DSA_meth_get_flags() return the name and flags associated with the DSA_METHOD respectively.</p>

<p>All other DSA_meth_get_*() functions return the appropriate function pointer that has been set in the DSA_METHOD, or NULL if no such pointer has yet been set.</p>

<p>DSA_meth_set1_name() and all DSA_meth_set_*() functions return 1 on success or 0 on failure.</p>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man3/DSA_new.html">DSA_new(3)</a>, <a href="../man3/DSA_new.html">DSA_new(3)</a>, <a href="../man3/DSA_generate_parameters.html">DSA_generate_parameters(3)</a>, <a href="../man3/DSA_generate_key.html">DSA_generate_key(3)</a>, <a href="../man3/DSA_dup_DH.html">DSA_dup_DH(3)</a>, <a href="../man3/DSA_do_sign.html">DSA_do_sign(3)</a>, <a href="../man3/DSA_set_method.html">DSA_set_method(3)</a>, <a href="../man3/DSA_SIG_new.html">DSA_SIG_new(3)</a>, <a href="../man3/DSA_sign.html">DSA_sign(3)</a>, <a href="../man3/DSA_size.html">DSA_size(3)</a>, <a href="../man3/DSA_get0_pqg.html">DSA_get0_pqg(3)</a></p>

<h1 id="HISTORY">HISTORY</h1>

<p>The functions described here were deprecated in OpenSSL 3.0.</p>

<p>The functions described here were added in OpenSSL 1.1.0.</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2016-2024 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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