soft_get_private_key_attribute
rv = soft_get_private_key_attribute(object_p, template);
rv = soft_get_private_key_attribute(basekey, &template);
rv = soft_get_private_key_attribute(basekey, &template);
rv = soft_get_private_key_attribute(key_p, &template);
extern CK_RV soft_get_private_key_attribute(soft_object_t *, CK_ATTRIBUTE_PTR);