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 (*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,