+int ossl_dh_is_foreign(const DH *dh)
+{
+#ifndef FIPS_MODULE
+ if (dh->engine != NULL || ossl_dh_get_method(dh) != DH_OpenSSL())
+ return 1;
+#endif
+ return 0;
+}
+
+static ossl_inline int dh_bn_dup_check(BIGNUM **out, const BIGNUM *f)
+{
+ if (f != NULL && (*out = BN_dup(f)) == NULL)
+ return 0;
+ return 1;
+}
+
+DH *ossl_dh_dup(const DH *dh, int selection)
+{
+ DH *dupkey = NULL;
+
+ /* Do not try to duplicate foreign DH keys */
+ if (ossl_dh_is_foreign(dh))
+ return NULL;
+
+ if ((dupkey = ossl_dh_new_ex(dh->libctx)) == NULL)
+ return NULL;
+
+ dupkey->length = DH_get_length(dh);
+ if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0
+ && !ossl_ffc_params_copy(&dupkey->params, &dh->params))
+ goto err;
+
+ dupkey->flags = dh->flags;
+
+ if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0
+ && ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0
+ || !dh_bn_dup_check(&dupkey->pub_key, dh->pub_key)))
+ goto err;
+
+ if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0
+ && ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0
+ || !dh_bn_dup_check(&dupkey->priv_key, dh->priv_key)))
+ goto err;
+
+#ifndef FIPS_MODULE
+ if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_DH,
+ &dupkey->ex_data, &dh->ex_data))
+ goto err;
+#endif
+
+ return dupkey;
+
+ err:
+ DH_free(dupkey);
+ return NULL;
+}
+