Unable to connect with the public key you've provided. Php | Codeigniter

Unable to connect with the public key you've provided.Unable to connect with the public key you've provided.

i am using codeigniter 3.1.x . Keys are valid . I have test the keys using filezilla client. Everything is working but here in php codeigniter am getting below error. Any buddy there who can help me to resolve this error. Or Can suggest any other php library with proper guidence. Thanks in advace

 function sftp()
    {
     $this->load->library('SFTP');
     $private_key=APPPATH.'sftp_keys/new_private.ppk';
     $public_key=APPPATH.'sftp_keys/new_public';
     $config=array();
     $config['hostname']='host';
     $config['username']='username';
     $config['port']='22';
     $config['public_key_url']=$public_key;
     $config['private_key_url']=$private_key;
     $config['method']='auth';
     $config['debug']=TRUE;
     $config['login_via_key']=TRUE;
     $this->sftp->initialize($config);
     
     $connect=$this->sftp->connect($config);
     var_dump($connect);
     $this->ftp->close();
    }

var_dump($config)

array(8) { 
  ["hostname"]=> string(13) "" 
  ["username"]=> string(7) "" 
  ["port"]=> string(2) "22" 
  ["public_key_url"]=> string(62) "/home/sgfasaco/public_html/qa/application/sftp_keys/new_public" 
  ["private_key_url"]=> string(71) "/home/sgfasaco/public_html/qa/application/sftp_keys/id_rsa(private).ppk" 
  ["method"]=> string(3) "key" 
  ["debug"]=> bool(true) 
  ["login_via_key"]=> bool(true)
} 

Yes i got the solution by trying different libraries. I found the best one working perfectly Flysystem Filesystem Abstraction for PHP (PHP library).

https://flysystem.thephpleague.com/v2/docs/

install the library using command.

composer require league/flysystem-sftp:^2.0

use below code to connect with SFTP using Filesystem.

<?php
require_once('vendor/autoload.php');
use League\Flysystem\Filesystem;
use League\Flysystem\PhpseclibV2\SftpConnectionProvider;
use League\Flysystem\PhpseclibV2\SftpAdapter;
use League\Flysystem\UnixVisibility\PortableVisibilityConverter;
use League\Flysystem\DirectoryAttributes;
use League\Flysystem\FileAttributes;
$private_key='sftp_keys/new_private.ppk';

$filesystem = new Filesystem(new SftpAdapter(
    new SftpConnectionProvider(
        'host', // host (required)
        'username', // username (required)
        null, // password (optional, default: null) set to null if privateKey is used
        $private_key, // private key (optional, default: null) can be used instead of password, set to null if password is set
        null, // passphrase (optional, default: null), set to null if privateKey is not used or has no passphrase
        22, // port (optional, default: 22)
        false, // use agent (optional, default: false)
        30, // timeout (optional, default: 10)
        10, // max tries (optional, default: 4)
        null, // host fingerprint (optional, default: null),
        null // connectivity checker (must be an implementation of 'League\Flysystem\PhpseclibV2\ConnectivityChecker' to check if a connection can be established (optional, omit if you don't need some special handling for setting reliable connections)
    ),
    '/', // root path (required)
    PortableVisibilityConverter::fromArray([
        'file' => [
            'public' => 0640,
            'private' => 0604,
        ],
        'dir' => [
            'public' => 0740,
            'private' => 7604,
        ],
    ])
));
$allFiles = $filesystem->listContents('Outbound')->toArray();
$response = $filesystem->write('Outbound/info.txt', 'Hello How are you',array());
if($response){
    echo "Success";
}else echo "Error";
print_r($allFiles );
?>

Composer.json looks like

{
    "name": "league/flysystem-sftp",
    "description": "Flysystem adapter for SFTP",
    "license": "MIT",
    "authors": [
        {
            "name": "Frank de Jonge",
            "email": "info@frenky.net"
        }
    ],
    "require": {
        "php": ">=5.6.0",
        "league/flysystem-sftp": "^2.1",
        "phpseclib/phpseclib": "~2.0"
    },
    "require-dev": {
        "mockery/mockery": "0.9.*",
        "phpunit/phpunit": "^5.7.25"
    },
    "autoload": {
        "psr-4": {
            "League\\Flysystem\\Sftp\\": "src/"
        }
    }
}