k5_base64_decode
der_cert = k5_base64_decode(b64, &dlen);
void *k5_base64_decode(const char *str, size_t *len_out);
data = k5_base64_decode((const char *)string, &len);
data = k5_base64_decode(*ntest, &len);
data = k5_base64_decode(t->result, &len);