Technolifeandmore: HTTP RSA Implementation

Hi, for this week we needed to implement the algorithm rsa in a web service, for the activity I choose php for WS.

The dinamic between server and user is the next:

The server has e and n, this keys are public.
The user has n and d, where d is the private key.
When a user open the page, server generate a x random number.
The user use this number for generate a response(r), the response is generate for a script, provided for the server.
Then the user put this r in the service and the server compare r with a num produced.
If this is correct the users are welcome, else the users are denied.

Important points:

In the autentification for the server we need to implement the same f(x), but this help us to compare, use fasmodexp(r, e, n), where r is the response of the user and e & n is the public key.

Code:
home.php


	<?php

	function getUsuarios($usuario)
	{
	include 'parametrosLogin/loginConnection.php';

	$link_C = "SELECT usuario FROM rsa_cripto";

	$link_CR = mysql_query($link_C, $conexion) or die(mysql_error());
	$link_C_rows = mysql_num_rows($link_CR);

	if ($link_C_rows> 0) {
	while ($link_C_Rrows = mysql_fetch_assoc($link_CR)) {
	$usuario = $link_C_Rrows['usuario'];
	echo "<option value=$usuario >$usuario</option>";
	}
	}
	}

	?>
	<html>

	<head>
	</head>

	<body>
	<!--<form action="home.php" method="post">-->
	<h1>RSA</h1>
	<form action="rsaAutentification.php" method="post">

	<a href="#">Script.py</a><br/>
	<label>Your x: </label>
	<input type="text" name="x" size = "10" value="<?php echo rand(0, 10)?>" required="required"/>

	<p>
	<h4>Autentification</h4>
	<label>User: </laberl>
	<select name="user" required="required">
	<option value="">---</option>
	<?php getUsuarios(); ?>
	</select><br/>
	<label>Respuesta:</label>
	<input type="text" name="respuesta" size = "10" required="required"/> </br>
	</p>

	<input type="submit" value="submit" /> </br>
	</form>
	</body>

	</html>

view raw gistfile1.php hosted with ❤ by GitHub

rsaAutentification.php

	<a href="home.php">Regresar</a><br/>
	<?php

	validar($_POST['user'], $_POST['respuesta'], $_POST['x']);

	function validar($usuario, $r, $x)
	{
	$lista = getUser($usuario);
	if($lista)
	{
	$e = $lista[0];
	$n = $lista[1];

	$y = f($x);
	$num = fastmodexp($r, $e, $n);

	if($y == $num)
	{
	echo "<h3>Welcome $usuario</h3>";
	echo "You can see 9gag<br/><br/>";
	echo "<iframe src='http://www.9gag.com' width='900' height='900'></iframe>";
	}
	else echo "Fail..!";
	echo "<br/><br/>";
	}
	else
	{
	echo "<h1>Usuario invalido<h1>";
	die();
	}
	}

	function getUser($usuario)
	{
	include 'parametrosLogin/loginConnection.php';

	$link_C = "SELECT e, n FROM rsa_cripto where usuario = '".$usuario."'";

	$link_CR = mysql_query($link_C, $conexion) or die(mysql_error());
	$link_C_rows = mysql_num_rows($link_CR);

	if ($link_C_rows> 0) {
	while ($link_C_Rrows = mysql_fetch_assoc($link_CR)) {
	$e = $link_C_Rrows['e'];
	$n = $link_C_Rrows['n'];
	}
	$lista = array($e, $n);
	return $lista;
	}

	else return False;
	}

	function f($x)
	{
	return ($x*2)+5;
	}

	function fastmodexp($x, $y, $mod)
	{
	$p = 1;
	$aux = $x;
	while($y > 0){
	if ($y % 2 == 1){
	$p = ($p * $aux) % $mod;
	}
	$aux = ($aux * $aux) % $mod;
	$y = $y >> 1;
	}
	return ($p);
	}

	?>

view raw gistfile1.php hosted with ❤ by GitHub

validation.py

view raw gistfile1.py hosted with ❤ by GitHub

Tabla Usuarios

create table rsa_cripto(id int not null auto_increment primary key, usuario varchar(20), e int(30), n int(30));

view raw gistfile1.sql hosted with ❤ by GitHub

result:

WebService:

You can check the program in the next link: ....

Note:

Php is a pussy, in my case when I use a big numbers the autentification fail, but checking in python the autentification is correct.

Technolifeandmore