int ENGINE_set_name(ENGINE *e, const char *name);
int ENGINE_set_RSA(ENGINE *e, const RSA_METHOD *rsa_meth);
int ENGINE_set_DSA(ENGINE *e, const DSA_METHOD *dsa_meth);
-int ENGINE_set_DH(ENGINE *e, DH_METHOD *dh_meth);
+int ENGINE_set_DH(ENGINE *e, const DH_METHOD *dh_meth);
int ENGINE_set_RAND(ENGINE *e, RAND_METHOD *rand_meth);
int ENGINE_set_BN_mod_exp(ENGINE *e, BN_MOD_EXP bn_mod_exp);
int ENGINE_set_BN_mod_exp_crt(ENGINE *e, BN_MOD_EXP_CRT bn_mod_exp_crt);
const char *ENGINE_get_name(ENGINE *e);
const RSA_METHOD *ENGINE_get_RSA(ENGINE *e);
const DSA_METHOD *ENGINE_get_DSA(ENGINE *e);
-DH_METHOD *ENGINE_get_DH(ENGINE *e);
+const DH_METHOD *ENGINE_get_DH(ENGINE *e);
RAND_METHOD *ENGINE_get_RAND(ENGINE *e);
BN_MOD_EXP ENGINE_get_BN_mod_exp(ENGINE *e);
BN_MOD_EXP_CRT ENGINE_get_BN_mod_exp_crt(ENGINE *e);