his may be NULL because there are no trusted certificates or because they are provided simply as a list using X509_STORE_CTX_set0_trusted_stack(). The certificate to be verified is set to <i>target</i>, and a list of additional certificates may be provided in <i>untrusted</i>, which will be untrusted but may be used to build the chain. The <i>target</i> certificate is not copied (its reference count is not updated), and the caller must not free it before verification is complete. Each of the <i>trust_store<