DH_meth_new (3)

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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(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 type is a structure used for the provision of custom implementations. It provides a set of of functions used by OpenSSL for the implementation of the various capabilities.

DH_meth_new() creates a new

structure. It should be given a unique name and a set of flags. The name should be a terminated string, which will be duplicated and stored in the object. It is the callers responsibility to free the original string. The flags will be used during the construction of a new object based on this . Any new object will have those flags set by default.

DH_meth_dup() creates a duplicate copy of the

object passed as a parameter. This might be useful for creating a new based on an existing one, but with some differences.

DH_meth_free() destroys a

structure and frees up any memory associated with it.

DH_meth_get0_name() will return a pointer to the name of this

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 to name. The string is duplicated and the copy is stored in the 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_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

It is the application's responsibility to free this data before the 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

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

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

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

instance respectively. This function will be called in response to the application calling DH_new() (if the current default is this one) or DH_new_method(). The DH_new() and DH_new_method() functions will allocate the memory for the new object, and a pointer to this newly allocated structure will be passed as a parameter to the function. This function may be

DH_meth_get_finish() and DH_meth_set_finish() get and set the function used for destroying an instance of a

object respectively. This function will be called in response to the application calling DH_free(). A pointer to the to be destroyed is passed as a parameter. The destroy function should be used for implementation specific clean up. The memory for the itself should not be freed by this function. This function may be

DH_meth_get_generate_params() and DH_meth_set_generate_params() get and set the function used for generating

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

RETURN VALUES

DH_meth_new() and DH_meth_dup() return the newly allocated object or on failure.

DH_meth_get0_name() and DH_meth_get_flags() return the name and flags associated with the

respectively.

All other DH_meth_get_*() functions return the appropriate function pointer that has been set in the

or 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(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 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

in the source distribution or at <www.openssl.org/source/license.html>.