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DH_METH_NEW(3)                      OpenSSL                     DH_METH_NEW(3)
NAME
       DH_meth_new, DH_meth_free, DH_meth_dup, DH_meth_get0_name,
       DH_meth_set1_name, DH_meth_get_flags, DH_meth_set_flags,
       DH_meth_get0_app_data, DH_meth_set0_app_data, DH_meth_get_generate_key,
       DH_meth_set_generate_key, DH_meth_get_compute_key,
       DH_meth_set_compute_key, DH_meth_get_bn_mod_exp,
       DH_meth_set_bn_mod_exp, DH_meth_get_init, DH_meth_set_init,
       DH_meth_get_finish, DH_meth_set_finish, DH_meth_get_generate_params,
       DH_meth_set_generate_params - Routines to build up DH methods
SYNOPSIS
        #include <openssl/dh.h>
        DH_METHOD *DH_meth_new(const char *name, int flags);
        void DH_meth_free(DH_METHOD *dhm);
        DH_METHOD *DH_meth_dup(const DH_METHOD *dhm);
        const char *DH_meth_get0_name(const DH_METHOD *dhm);
        int DH_meth_set1_name(DH_METHOD *dhm, const char *name);
        int DH_meth_get_flags(const DH_METHOD *dhm);
        int DH_meth_set_flags(DH_METHOD *dhm, int flags);
        void *DH_meth_get0_app_data(const DH_METHOD *dhm);
        int DH_meth_set0_app_data(DH_METHOD *dhm, void *app_data);
        int (*DH_meth_get_generate_key(const DH_METHOD *dhm))(DH *);
        int DH_meth_set_generate_key(DH_METHOD *dhm, int (*generate_key)(DH *));
        int (*DH_meth_get_compute_key(const DH_METHOD *dhm))
            (unsigned char *key, const BIGNUM *pub_key, DH *dh);
        int DH_meth_set_compute_key(DH_METHOD *dhm,
            int (*compute_key)(unsigned char *key, const BIGNUM *pub_key, DH *dh));
        int (*DH_meth_get_bn_mod_exp(const DH_METHOD *dhm))
            (const DH *dh, BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
             const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
        int DH_meth_set_bn_mod_exp(DH_METHOD *dhm,
            int (*bn_mod_exp)(const DH *dh, BIGNUM *r, const BIGNUM *a,
                              const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,
                              BN_MONT_CTX *m_ctx));
        int (*DH_meth_get_init(const DH_METHOD *dhm))(DH *);
        int DH_meth_set_init(DH_METHOD *dhm, int (*init)(DH *));
        int (*DH_meth_get_finish(const DH_METHOD *dhm))(DH *);
        int DH_meth_set_finish(DH_METHOD *dhm, int (*finish)(DH *));
        int (*DH_meth_get_generate_params(const DH_METHOD *dhm))
            (DH *, int, int, BN_GENCB *);
        int DH_meth_set_generate_params(DH_METHOD *dhm,
            int (*generate_params)(DH *, int, int, BN_GENCB *));
DESCRIPTION
       The DH_METHOD type is a structure used for the provision of custom DH
       implementations. It provides a set of functions used by OpenSSL for the
       implementation of the various DH capabilities.
       DH_meth_new() creates a new DH_METHOD structure. It should be given a
       unique name and a set of flags. The name should be a NULL terminated
       string, which will be duplicated and stored in the DH_METHOD object. It
       is the callers responsibility to free the original string. The flags
       will be used during the construction of a new DH object based on this
       DH_METHOD. Any new DH object will have those flags set by default.
       DH_meth_dup() creates a duplicate copy of the DH_METHOD object passed
       as a parameter. This might be useful for creating a new DH_METHOD based
       on an existing one, but with some differences.
       DH_meth_free() destroys a DH_METHOD structure and frees up any memory
       associated with it.
       DH_meth_get0_name() will return a pointer to the name of this
       DH_METHOD. This is a pointer to the internal name string and so should
       not be freed by the caller. DH_meth_set1_name() sets the name of the
       DH_METHOD to name. The string is duplicated and the copy is stored in
       the DH_METHOD structure, so the caller remains responsible for freeing
       the memory associated with the name.
       DH_meth_get_flags() returns the current value of the flags associated
       with this DH_METHOD. DH_meth_set_flags() provides the ability to set
       these flags.
       The functions DH_meth_get0_app_data() and DH_meth_set0_app_data()
       provide the ability to associate implementation specific data with the
       DH_METHOD. It is the application's responsibility to free this data
       before the DH_METHOD is freed via a call to DH_meth_free().
       DH_meth_get_generate_key() and DH_meth_set_generate_key() get and set
       the function used for generating a new DH key pair respectively. This
       function will be called in response to the application calling
       DH_generate_key(). The parameter for the function has the same meaning
       as for DH_generate_key().
       DH_meth_get_compute_key() and DH_meth_set_compute_key() get and set the
       function used for computing a new DH shared secret respectively. This
       function will be called in response to the application calling
       DH_compute_key(). The parameters for the function have the same meaning
       as for DH_compute_key().
       DH_meth_get_bn_mod_exp() and DH_meth_set_bn_mod_exp() get and set the
       function used for computing the following value:
        r = a ^ p mod m
       This function will be called by the default OpenSSL function for
       DH_generate_key(). The result is stored in the r parameter. This
       function may be NULL unless using the default generate key function, in
       which case it must be present.
       DH_meth_get_init() and DH_meth_set_init() get and set the function used
       for creating a new DH instance respectively. This function will be
       called in response to the application calling DH_new() (if the current
       default DH_METHOD is this one) or DH_new_method(). The DH_new() and
       DH_new_method() functions will allocate the memory for the new DH
       object, and a pointer to this newly allocated structure will be passed
       as a parameter to the function. This function may be NULL.
       DH_meth_get_finish() and DH_meth_set_finish() get and set the function
       used for destroying an instance of a DH object respectively. This
       function will be called in response to the application calling
       DH_free(). A pointer to the DH to be destroyed is passed as a
       parameter. The destroy function should be used for DH implementation
       specific clean up. The memory for the DH itself should not be freed by
       this function. This function may be NULL.
       DH_meth_get_generate_params() and DH_meth_set_generate_params() get and
       set the function used for generating DH parameters respectively. This
       function will be called in response to the application calling
       DH_generate_parameters_ex() (or DH_generate_parameters()). The
       parameters for the function have the same meaning as for
       DH_generate_parameters_ex(). This function may be NULL.
RETURN VALUES
       DH_meth_new() and DH_meth_dup() return the newly allocated DH_METHOD
       object or NULL on failure.
       DH_meth_get0_name() and DH_meth_get_flags() return the name and flags
       associated with the DH_METHOD respectively.
       All other DH_meth_get_*() functions return the appropriate function
       pointer that has been set in the DH_METHOD, or NULL if no such pointer
       has yet been set.
       DH_meth_set1_name() and all DH_meth_set_*() functions return 1 on
       success or 0 on failure.
SEE ALSO
       DH_new(3), DH_new(3), DH_generate_parameters(3), DH_generate_key(3),
       DH_set_method(3), DH_size(3), DH_get0_pqg(3)
HISTORY
       The functions described here were added in OpenSSL 1.1.0.
COPYRIGHT
       Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
       Licensed under the OpenSSL license (the "License").  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
       <https://www.openssl.org/source/license.html>;.
1.1.1k                            2021-03-25                    DH_METH_NEW(3)