node.js crypto stuff, signing and verifying

bufferutils.js

var bufferXOR = function(a,b){
    c = Buffer(20);
    for(i = 0; i<20;i++){
        c[i] = a[i] ^ b[i];
    }
    return c;
}

var getKBucketId = function(buf){
    for (i = 0; i < 20; i++){
        if(buf[i]>0){
            return 8*i+getPosFirsOneInByte(buf[i]) 
        }
    }
    return 0;
}


function getPosFirsOneInByte(byte){
    var mask = 128; //10000000
    for (i = 0; i < 8; i++){
        if ((mask & byte) != 0){
            return i;
        }
        mask = mask >> 1;
    }
    return 0
}

exports.getKBucketId = getKBucketId;
exports.bufferXOR = bufferXOR;
exports.getPosFirsOneInByte = getPosFirsOneInByte;

bufs.js

var dgram = require("dgram");


var parseRequest = function(message){
    if (message.length != 22){
        console.log('message is not the right side' + message.length);
    }
    else{
        console.log(message);
    }
}

var server = dgram.createSocket("udp4",parseRequest);

server.bind(41234);
// server listening 0.0.0.0:41234



var a = new Buffer( [0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0]);
var b = new Buffer( [0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,255,0,0,0,0]);


function bufferXOR(a,b){
    c = Buffer(20);
    for(i = 0; i<20;i++){
        c[i] = a[i] ^ b[i];
    }
    return c;
}

function getKBucketId(buf){
    for (i = 0; i < 20; i++){
        if(buf[i]>0){
            return 8*i+buf[i] 
        }
    }
    return 0;
}

client.js

var dgram = require("dgram");

//~ a = new Buffer( [0,0,200,0,0,0,0,0,0,0,0,1,0,0,0,8,0,0,0,0]);
//~ b = new Buffer( [0,5,0,0,0,0,0,0,0,0,0,1,0,0,0,8,0,0,0,0]);
//~ c = new Buffer( [255,5,0,0,0,0,0,0,0,0,0,1,0,0,0,255,0,0,0,0]);
d = new Buffer([127,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1]);

var client = dgram.createSocket("udp4");
//~ client.send(a, 0, a.length, 41234, "localhost");
//~ client.send(b, 0, b.length, 41234, "localhost");
//~ client.send(c, 0, c.length, 41234, "localhost");
client.send(d, 0, d.length, 41234, "localhost");

gistfile1.js

//falta ver como criar os pems usando oi node.js

EDIT: instalar este módulo para gerar as chaves! BAM problem solved!!!
// https://github.com/juliangruber/keypair

var crypto = require('crypto');
var fs = require('fs');

var pem = fs.readFileSync('private_key.pem');
var key = pem.toString('ascii');

var sign = crypto.createSign('RSA-SHA256');
sign.update('aaaaaaaaaaa');  // data from your file would go here

//We created a signature
var sig = sign.sign(key, 'hex');

console.log("printing the signature!!!")
console.log(sig);

var public_key_pem = fs.readFileSync('public_key.pem')

var verif = crypto.createVerify('RSA-SHA256');
verif.update('aaaaaaaaaaa')

console.log(verif.verify(public_key_pem, sig, 'hex'));

//BAM!!! verificamos que a string 'aaaaaaaaaaa' foi assinada pela
//+esspa que tem a provate key correspondente a public key nosrecebemos

server.js

var dgram = require("dgram"),
    bufutils = require("./bufferutils.js");


var parseRequest = function(message){
    if (message.length != 20){
        console.log('message is not the right side' + message.length);
    }
    else{
        console.log("this is on bucket: " + bufutils.getKBucketId(message));
    }
}

var server = dgram.createSocket("udp4",parseRequest);

server.bind(41234);