PHP RSA 使用OPENSSL_NO_PADDING模式加密，返回 false

>我用RSA方法加密密码，我设置了填充模式"OPENSSL_NO_PADDING"，它返回false。但是如果我删除填充模式参数，请将其保留为默认值，加密成功。

$pass = 'gmwtwjfws';
$encrypetd_pass = '';
$pub_key = '-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAs+JvfyTOMHqvjxHJyDZG
HZpz3atV7qcOT8mijXGGG3S+8Bb2p2kREGJwrzC2IIErCQUcZ3Wa3wTugKQDxqXE
SPt76HN2353ufegbvTI9kYgK0MLFpY8OZAMsaTytVrvUEVHjqGXZO4z7oVTqByuB
wcZAvK+sN39+MqisS6ZejACbbQLkWZgcSgt5wBAaDaEa2lvRYcVbNyO/mqTU6SSf
d+w78uM07BpmxhimOMwf+l/qs+Z04LUm4Ay7b+AHHAwbaHeehC1wInzNDfipgR0H
0FCa/LOnEblj2HVpptB/NY4XNG+CDHTBKkxzEw92D/Nj1JIlr1oP0l+/VdAnxxiW
uQIDAQAB
-----END PUBLIC KEY-----';
$result = openssl_public_encrypt($pass, $encrypetd_pass, $pub_key);
var_dump($result);  //return false
exit;

更重要的是，我对公钥的格式感到困惑。如果我保留默认的填充模式，并且公钥的格式如上，它会返回 true。但是当我按如下方式修改密钥格式（删除一个新行）时，它返回 false。谁能解释一下原因？谢谢非常糊涂。

$pub_key = '-----BEGIN PUBLIC KEY-----MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAs+JvfyTOMHqvjxHJyDZGHZpz3atV7qcOT8mijXGGG3S+8Bb2p2kREGJwrzC2IIErCQUcZ3Wa3wTugKQDxqXE
SPt76HN2353ufegbvTI9kYgK0MLFpY8OZAMsaTytVrvUEVHjqGXZO4z7oVTqByuB
wcZAvK+sN39+MqisS6ZejACbbQLkWZgcSgt5wBAaDaEa2lvRYcVbNyO/mqTU6SSf
d+w78uM07BpmxhimOMwf+l/qs+Z04LUm4Ay7b+AHHAwbaHeehC1wInzNDfipgR0H
0FCa/LOnEblj2HVpptB/NY4XNG+CDHTBKkxzEw92D/Nj1JIlr1oP0l+/VdAnxxiW
uQIDAQAB
-----END PUBLIC KEY-----';