DH_set_method(3) OpenSSL DH_set_method(3)NAME
DH_set_default_method, DH_get_default_method, DH_set_method,
DH_new_method, DH_OpenSSL - select DH method
SYNOPSIS
#include <openssl/dh.h>
void DH_set_default_method(DH_METHOD *meth);
DH_METHOD *DH_get_default_method(void);
DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth);
DH *DH_new_method(DH_METHOD *meth);
DH_METHOD *DH_OpenSSL(void);
DESCRIPTION
A DH_METHOD specifies the functions that OpenSSL uses for Diffie-
Hellman operations. By modifying the method, alternative
implementations such as hardware accelerators may be used.
Initially, the default is to use the OpenSSL internal implementation.
DH_OpenSSL() returns a pointer to that method.
DH_set_default_method() makes meth the default method for all DH
structures created later.
DH_get_default_method() returns a pointer to the current default
method.
DH_set_method() selects meth for all operations using the structure dh.
DH_new_method() allocates and initializes a DH structure so that method
will be used for the DH operations. If method is NULL, the default
method is used.
THE DH_METHOD STRUCTURE
typedef struct dh_meth_st
{
/* name of the implementation */
const char *name;
/* generate private and public DH values for key agreement */
int (*generate_key)(DH *dh);
/* compute shared secret */
int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh);
/* compute r = a ^ p mod m (May be NULL for some implementations) */
int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx,
BN_MONT_CTX *m_ctx);
/* called at DH_new */
int (*init)(DH *dh);
/* called at DH_free */
int (*finish)(DH *dh);
int flags;
char *app_data; /* ?? */
} DH_METHOD;
RETURN VALUESDH_OpenSSL() and DH_get_default_method() return pointers to the
respective DH_METHODs.
DH_set_default_method() returns no value.
DH_set_method() returns a pointer to the DH_METHOD previously
associated with dh.
DH_new_method() returns NULL and sets an error code that can be
obtained by ERR_get_error(3) if the allocation fails. Otherwise it
returns a pointer to the newly allocated structure.
SEE ALSOdh(3), DH_new(3)HISTORYDH_set_default_method(), DH_get_default_method(), DH_set_method(),
DH_new_method() and DH_OpenSSL() were added in OpenSSL 0.9.4.
3rd Berkeley Distribution 0.9.6m DH_set_method(3)