Automatización y control de Sistemas Dinámicos: RSA-Firmas Digitales

For this homework I need to implement a HTTP public-key repository for key exchange that employs RSA-Based digital signatures, I used PHP and a little database in mysql also a little script in Python.

This is the PHP+MySQL code

	<?php
	require("conn.php");
	?>
	<html>
	<head>
	<script>
	function generar(inf,sup){
	nP = sup - inf;
	rnd = Math.random() * nP;
	rnd = Math.round(rnd);
	document.formulario.challengen.value=parseInt(inf) + rnd;
	}


	</script>
	</head>
	<a href="script.py">Descargar script</a>
	<form name="formulario" method="POST" action="validar.php" >
	<b>Challenge:</b><input type="text" name="challengen"><input type="button" value="Generate" onclick="generar(0,100)">
	<br><b>Usuario:</b><select name="user">
	<?php
	$query="SELECT user FROM users";
	$result=mysql_query($ query,$conn);
	while( $row=mysql_fetch_array($ result)){
	echo "<option value='". $row["user"]."'>".$ row["user"]."</option>";
	}
	?>
	</select>
	<br><b>Respuesta:</b><input type="text" name="response">
	<br><input type="submit" value="submit">

	<?php
	function f($x){
	return ($x*x+3);
	}

	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);
	}


	if(isset( $_POST['response']) and isset($ _POST['user']) and isset($_POST['challengen'])){
	$usuario =$ _POST['user'];
	$x =$ _POST['challengen'];
	$r =$ _POST['response'];
	$query="SELECT E,N From users WHERE user = '".$ usuario."'";
	$result=mysql_query($ query,$conn);
	$publica = mysql_fetch_array($ result);


	$e =$ publica["E"];
	$n =$ publica["N"];

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

	if ( $y ==$ num){
	echo "<strong><h2>Yes, it was ". $usuario ." :)</h2></strong>";
	} else {
	echo "<strong><h2>No, it wasn't ". $usuario ." :(</h2></strong>";
	}
	} ?>
	</form>
	</html>

view raw gistfile1.php hosted with ❤ by GitHub

This is the script in python

	def f(x):
	return x*x+3

	def 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

	def main():
	x = int(raw_input("x: "))
	d = int(raw_input("d: "))
	n = int(raw_input("n: "))
	y = f(x)
	r = fastmodexp(y, d, n)
	print "La r es = " + str(r)

	main()

view raw gistfile1.py hosted with ❤ by GitHub

This is the authentication with the web service, here is the validation

Automatización y control de Sistemas Dinámicos

jueves, 20 de septiembre de 2012

RSA-Firmas Digitales

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