xref: /openssl/doc/man3/DH_meth_new.pod (revision 7ed6de99)
1=pod
2
3=head1 NAME
4
5DH_meth_new, DH_meth_free, DH_meth_dup, DH_meth_get0_name, DH_meth_set1_name,
6DH_meth_get_flags, DH_meth_set_flags, DH_meth_get0_app_data,
7DH_meth_set0_app_data, DH_meth_get_generate_key, DH_meth_set_generate_key,
8DH_meth_get_compute_key, DH_meth_set_compute_key, DH_meth_get_bn_mod_exp,
9DH_meth_set_bn_mod_exp, DH_meth_get_init, DH_meth_set_init, DH_meth_get_finish,
10DH_meth_set_finish, DH_meth_get_generate_params,
11DH_meth_set_generate_params - Routines to build up DH methods
12
13=head1 SYNOPSIS
14
15 #include <openssl/dh.h>
16
17The following functions have been deprecated since OpenSSL 3.0, and can be
18hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
19see L<openssl_user_macros(7)>:
20
21 DH_METHOD *DH_meth_new(const char *name, int flags);
22
23 void DH_meth_free(DH_METHOD *dhm);
24
25 DH_METHOD *DH_meth_dup(const DH_METHOD *dhm);
26
27 const char *DH_meth_get0_name(const DH_METHOD *dhm);
28 int DH_meth_set1_name(DH_METHOD *dhm, const char *name);
29
30 int DH_meth_get_flags(const DH_METHOD *dhm);
31 int DH_meth_set_flags(DH_METHOD *dhm, int flags);
32
33 void *DH_meth_get0_app_data(const DH_METHOD *dhm);
34 int DH_meth_set0_app_data(DH_METHOD *dhm, void *app_data);
35
36 int (*DH_meth_get_generate_key(const DH_METHOD *dhm))(DH *);
37 int DH_meth_set_generate_key(DH_METHOD *dhm, int (*generate_key)(DH *));
38
39 int (*DH_meth_get_compute_key(const DH_METHOD *dhm))
40     (unsigned char *key, const BIGNUM *pub_key, DH *dh);
41 int DH_meth_set_compute_key(DH_METHOD *dhm,
42     int (*compute_key)(unsigned char *key, const BIGNUM *pub_key, DH *dh));
43
44 int (*DH_meth_get_bn_mod_exp(const DH_METHOD *dhm))
45     (const DH *dh, BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
46      const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
47 int DH_meth_set_bn_mod_exp(DH_METHOD *dhm,
48     int (*bn_mod_exp)(const DH *dh, BIGNUM *r, const BIGNUM *a,
49                       const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,
50                       BN_MONT_CTX *m_ctx));
51
52 int (*DH_meth_get_init(const DH_METHOD *dhm))(DH *);
53 int DH_meth_set_init(DH_METHOD *dhm, int (*init)(DH *));
54
55 int (*DH_meth_get_finish(const DH_METHOD *dhm))(DH *);
56 int DH_meth_set_finish(DH_METHOD *dhm, int (*finish)(DH *));
57
58 int (*DH_meth_get_generate_params(const DH_METHOD *dhm))
59     (DH *, int, int, BN_GENCB *);
60 int DH_meth_set_generate_params(DH_METHOD *dhm,
61     int (*generate_params)(DH *, int, int, BN_GENCB *));
62
63=head1 DESCRIPTION
64
65All of the functions described on this page are deprecated.
66Applications should instead use the provider APIs.
67
68The B<DH_METHOD> type is a structure used for the provision of custom DH
69implementations. It provides a set of functions used by OpenSSL for the
70implementation of the various DH capabilities.
71
72DH_meth_new() creates a new B<DH_METHOD> structure. It should be given a
73unique B<name> and a set of B<flags>. The B<name> should be a NULL terminated
74string, which will be duplicated and stored in the B<DH_METHOD> object. It is
75the callers responsibility to free the original string. The flags will be used
76during the construction of a new B<DH> object based on this B<DH_METHOD>. Any
77new B<DH> object will have those flags set by default.
78
79DH_meth_dup() creates a duplicate copy of the B<DH_METHOD> object passed as a
80parameter. This might be useful for creating a new B<DH_METHOD> based on an
81existing one, but with some differences.
82
83DH_meth_free() destroys a B<DH_METHOD> structure and frees up any memory
84associated with it. If the argument is NULL, nothing is done.
85
86DH_meth_get0_name() will return a pointer to the name of this DH_METHOD. This
87is a pointer to the internal name string and so should not be freed by the
88caller. DH_meth_set1_name() sets the name of the DH_METHOD to B<name>. The
89string is duplicated and the copy is stored in the DH_METHOD structure, so the
90caller remains responsible for freeing the memory associated with the name.
91
92DH_meth_get_flags() returns the current value of the flags associated with this
93DH_METHOD. DH_meth_set_flags() provides the ability to set these flags.
94
95The functions DH_meth_get0_app_data() and DH_meth_set0_app_data() provide the
96ability to associate implementation specific data with the DH_METHOD. It is
97the application's responsibility to free this data before the DH_METHOD is
98freed via a call to DH_meth_free().
99
100DH_meth_get_generate_key() and DH_meth_set_generate_key() get and set the
101function used for generating a new DH key pair respectively. This function will
102be called in response to the application calling DH_generate_key(). The
103parameter for the function has the same meaning as for DH_generate_key().
104
105DH_meth_get_compute_key() and DH_meth_set_compute_key() get and set the
106function used for computing a new DH shared secret respectively. This function
107will be called in response to the application calling DH_compute_key(). The
108parameters for the function have the same meaning as for DH_compute_key().
109
110DH_meth_get_bn_mod_exp() and DH_meth_set_bn_mod_exp() get and set the function
111used for computing the following value:
112
113 r = a ^ p mod m
114
115This function will be called by the default OpenSSL function for
116DH_generate_key(). The result is stored in the B<r> parameter. This function
117may be NULL unless using the default generate key function, in which case it
118must be present.
119
120DH_meth_get_init() and DH_meth_set_init() get and set the function used
121for creating a new DH instance respectively. This function will be
122called in response to the application calling DH_new() (if the current default
123DH_METHOD is this one) or DH_new_method(). The DH_new() and DH_new_method()
124functions will allocate the memory for the new DH object, and a pointer to this
125newly allocated structure will be passed as a parameter to the function. This
126function may be NULL.
127
128DH_meth_get_finish() and DH_meth_set_finish() get and set the function used
129for destroying an instance of a DH object respectively. This function will be
130called in response to the application calling DH_free(). A pointer to the DH
131to be destroyed is passed as a parameter. The destroy function should be used
132for DH implementation specific clean up. The memory for the DH itself should
133not be freed by this function. This function may be NULL.
134
135DH_meth_get_generate_params() and DH_meth_set_generate_params() get and set the
136function used for generating DH parameters respectively. This function will be
137called in response to the application calling DH_generate_parameters_ex() (or
138DH_generate_parameters()). The parameters for the function have the same
139meaning as for DH_generate_parameters_ex(). This function may be NULL.
140
141=head1 RETURN VALUES
142
143DH_meth_new() and DH_meth_dup() return the newly allocated DH_METHOD object
144or NULL on failure.
145
146DH_meth_get0_name() and DH_meth_get_flags() return the name and flags
147associated with the DH_METHOD respectively.
148
149All other DH_meth_get_*() functions return the appropriate function pointer
150that has been set in the DH_METHOD, or NULL if no such pointer has yet been
151set.
152
153DH_meth_set1_name() and all DH_meth_set_*() functions return 1 on success or
1540 on failure.
155
156=head1 SEE ALSO
157
158L<DH_new(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>,
159L<DH_set_method(3)>, L<DH_size(3)>, L<DH_get0_pqg(3)>
160
161=head1 HISTORY
162
163All of these functions were deprecated in OpenSSL 3.0.
164
165The functions described here were added in OpenSSL 1.1.0.
166
167=head1 COPYRIGHT
168
169Copyright 2016-2024 The OpenSSL Project Authors. All Rights Reserved.
170
171Licensed under the Apache License 2.0 (the "License").  You may not use
172this file except in compliance with the License.  You can obtain a copy
173in the file LICENSE in the source distribution or at
174L<https://www.openssl.org/source/license.html>.
175
176=cut
177