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 17 DH_METHOD *DH_meth_new(const char *name, int flags); 18 19 void DH_meth_free(DH_METHOD *dhm); 20 21 DH_METHOD *DH_meth_dup(const DH_METHOD *dhm); 22 23 const char *DH_meth_get0_name(const DH_METHOD *dhm); 24 int DH_meth_set1_name(DH_METHOD *dhm, const char *name); 25 26 int DH_meth_get_flags(const DH_METHOD *dhm); 27 int DH_meth_set_flags(DH_METHOD *dhm, int flags); 28 29 void *DH_meth_get0_app_data(const DH_METHOD *dhm); 30 int DH_meth_set0_app_data(DH_METHOD *dhm, void *app_data); 31 32 int (*DH_meth_get_generate_key(const DH_METHOD *dhm))(DH *); 33 int DH_meth_set_generate_key(DH_METHOD *dhm, int (*generate_key)(DH *)); 34 35 int (*DH_meth_get_compute_key(const DH_METHOD *dhm)) 36 (unsigned char *key, const BIGNUM *pub_key, DH *dh); 37 int DH_meth_set_compute_key(DH_METHOD *dhm, 38 int (*compute_key)(unsigned char *key, const BIGNUM *pub_key, DH *dh)); 39 40 int (*DH_meth_get_bn_mod_exp(const DH_METHOD *dhm)) 41 (const DH *dh, BIGNUM *r, const BIGNUM *a, const BIGNUM *p, 42 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); 43 int DH_meth_set_bn_mod_exp(DH_METHOD *dhm, 44 int (*bn_mod_exp)(const DH *dh, BIGNUM *r, const BIGNUM *a, 45 const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx, 46 BN_MONT_CTX *m_ctx)); 47 48 int (*DH_meth_get_init(const DH_METHOD *dhm))(DH *); 49 int DH_meth_set_init(DH_METHOD *dhm, int (*init)(DH *)); 50 51 int (*DH_meth_get_finish(const DH_METHOD *dhm))(DH *); 52 int DH_meth_set_finish(DH_METHOD *dhm, int (*finish)(DH *)); 53 54 int (*DH_meth_get_generate_params(const DH_METHOD *dhm)) 55 (DH *, int, int, BN_GENCB *); 56 int DH_meth_set_generate_params(DH_METHOD *dhm, 57 int (*generate_params)(DH *, int, int, BN_GENCB *)); 58 59=head1 DESCRIPTION 60 61The B<DH_METHOD> type is a structure used for the provision of custom DH 62implementations. It provides a set of functions used by OpenSSL for the 63implementation of the various DH capabilities. 64 65DH_meth_new() creates a new B<DH_METHOD> structure. It should be given a 66unique B<name> and a set of B<flags>. The B<name> should be a NULL terminated 67string, which will be duplicated and stored in the B<DH_METHOD> object. It is 68the callers responsibility to free the original string. The flags will be used 69during the construction of a new B<DH> object based on this B<DH_METHOD>. Any 70new B<DH> object will have those flags set by default. 71 72DH_meth_dup() creates a duplicate copy of the B<DH_METHOD> object passed as a 73parameter. This might be useful for creating a new B<DH_METHOD> based on an 74existing one, but with some differences. 75 76DH_meth_free() destroys a B<DH_METHOD> structure and frees up any memory 77associated with it. 78 79DH_meth_get0_name() will return a pointer to the name of this DH_METHOD. This 80is a pointer to the internal name string and so should not be freed by the 81caller. DH_meth_set1_name() sets the name of the DH_METHOD to B<name>. The 82string is duplicated and the copy is stored in the DH_METHOD structure, so the 83caller remains responsible for freeing the memory associated with the name. 84 85DH_meth_get_flags() returns the current value of the flags associated with this 86DH_METHOD. DH_meth_set_flags() provides the ability to set these flags. 87 88The functions DH_meth_get0_app_data() and DH_meth_set0_app_data() provide the 89ability to associate implementation specific data with the DH_METHOD. It is 90the application's responsibility to free this data before the DH_METHOD is 91freed via a call to DH_meth_free(). 92 93DH_meth_get_generate_key() and DH_meth_set_generate_key() get and set the 94function used for generating a new DH key pair respectively. This function will 95be called in response to the application calling DH_generate_key(). The 96parameter for the function has the same meaning as for DH_generate_key(). 97 98DH_meth_get_compute_key() and DH_meth_set_compute_key() get and set the 99function used for computing a new DH shared secret respectively. This function 100will be called in response to the application calling DH_compute_key(). The 101parameters for the function have the same meaning as for DH_compute_key(). 102 103DH_meth_get_bn_mod_exp() and DH_meth_set_bn_mod_exp() get and set the function 104used for computing the following value: 105 106 r = a ^ p mod m 107 108This function will be called by the default OpenSSL function for 109DH_generate_key(). The result is stored in the B<r> parameter. This function 110may be NULL unless using the default generate key function, in which case it 111must be present. 112 113DH_meth_get_init() and DH_meth_set_init() get and set the function used 114for creating a new DH instance respectively. This function will be 115called in response to the application calling DH_new() (if the current default 116DH_METHOD is this one) or DH_new_method(). The DH_new() and DH_new_method() 117functions will allocate the memory for the new DH object, and a pointer to this 118newly allocated structure will be passed as a parameter to the function. This 119function may be NULL. 120 121DH_meth_get_finish() and DH_meth_set_finish() get and set the function used 122for destroying an instance of a DH object respectively. This function will be 123called in response to the application calling DH_free(). A pointer to the DH 124to be destroyed is passed as a parameter. The destroy function should be used 125for DH implementation specific clean up. The memory for the DH itself should 126not be freed by this function. This function may be NULL. 127 128DH_meth_get_generate_params() and DH_meth_set_generate_params() get and set the 129function used for generating DH parameters respectively. This function will be 130called in response to the application calling DH_generate_parameters_ex() (or 131DH_generate_parameters()). The parameters for the function have the same 132meaning as for DH_generate_parameters_ex(). This function may be NULL. 133 134=head1 RETURN VALUES 135 136DH_meth_new() and DH_meth_dup() return the newly allocated DH_METHOD object 137or NULL on failure. 138 139DH_meth_get0_name() and DH_meth_get_flags() return the name and flags 140associated with the DH_METHOD respectively. 141 142All other DH_meth_get_*() functions return the appropriate function pointer 143that has been set in the DH_METHOD, or NULL if no such pointer has yet been 144set. 145 146DH_meth_set1_name() and all DH_meth_set_*() functions return 1 on success or 1470 on failure. 148 149=head1 SEE ALSO 150 151L<DH_new(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>, 152L<DH_set_method(3)>, L<DH_size(3)>, L<DH_get0_pqg(3)> 153 154=head1 HISTORY 155 156The functions described here were added in OpenSSL 1.1.0. 157 158=head1 COPYRIGHT 159 160Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved. 161 162Licensed under the OpenSSL license (the "License"). You may not use 163this file except in compliance with the License. You can obtain a copy 164in the file LICENSE in the source distribution or at 165L<https://www.openssl.org/source/license.html>. 166 167=cut 168