PHP - 解密 - OpenSSL

Question

加密已正确完成，但何时使用openssl_get_privatekey并保存在$key_resource中，此值为空值，因此会引发错误：openssl_private_decrypt(): key parameter is not a valid private key in ...

    function encriptarDatos($datos){
        $fp=fopen("public.key","r"); 
        $pub_key=fread($fp,8192); 
        fclose($fp); 
        $key_resource = openssl_get_publickey($pub_key); 

        openssl_public_encrypt($datos,$encriptado,$key_resource ); 
        /*uses the already existing key resource*/ 
        return(base64_encode($encriptado));
    }

function desencriptarDatos($datos){
        $fp=fopen("private.key","r"); 
        $priv_key=fread($fp,8192); 
        fclose($fp); 
        echo "priv_key: $priv_key <br/><br/>";
        $key_resource = openssl_get_privatekey($priv_key);
        echo "key_resourse: $key_resource";

        openssl_private_decrypt($datos,$desencriptado,$key_resource); 
        /*uses the already existing key resource*/ 
        return(base64_encode($desencriptado));
    }

然后我改变了它：

        $fp=fopen("private.key","r"); 
        $priv_key=fread($fp,8192); 
        fclose($fp); 

        openssl_private_decrypt($datos, $desencriptado, openssl_pkey_get_private($priv_key, "phrase"));
        /*uses the already existing key resource*/ 
        return(base64_encode($desencriptado));

但结果也是null