Hacked Projects

Android sdk vs AndEngine vs libGDX

2012-03-03T18:47:00.000-08:00

As the title says, soon I will begin to work on a game for android, so I decided to do a little test between Android SDK, AndEngine and libGDX. The results left me so amazed that I decided to put a video on youtube, hope you enjoy.

Joule Thief

2012-02-29T23:53:00.000-08:00

Well ... it has been a whole month without a single post ^^ but this time it was for good reason, I was in school exams and they are going pretty good!

Now on-topic.

In these last days I've been thinking about many ways to save and produce electric energy. Almost none of the ideas resulted, but there is one that has worked wonderfully and that's what I've been talking about, it's called "Joule Thief".

According to wikipedia, joule thief is a term used to describe a self-oscillator energy booster, simple and low cost.

The peculiarity of this small circuit is to use almost all the energy of a battery cell, even after reaching that point that supposedly the battery is exhausted.

This is a possible electrical schematic, although there are many variations

And at the pictures of construction

For the coil, I used a metal core taken from a computer, the number of turns and the thickness of the wire was random.

Now the usefulness of this depends on our imagination, maybe light an LED with a single 1.5V cell, even use an old battery to recharge a Ni-Cd battery...

Good Joule Thief's :P

The internet status: SOPA

2012-01-26T20:20:00.000-08:00

Hi, it makes a long time since I wrote anything. I hope you had a good new year, because I hadn’t...

Now on-topic, usually I’m not interested about news, I just don’t have patience, but in these last days I've been following some tweets, the central topic: SOPA and PIPA

But what is this?

Well…in Portuguese SOPA is soup and PIPA is barrel xD

According to wikipedia

“The Stop Online Piracy Act (SOPA) is a United States bill Introduced by U.S. Representative Lamar S. Smith (R-TX) to expand the Ability of U.S. law enforcement to fight online copyrighted Trafficking in counterfeit goods and intellectual property”

“The PROTECT IP Act (Preventing Real Online Threats to Economic Creativity and Theft of Intellectual Property Act, or PIPA) is to proposed law with the Stated goal of giving the U.S. government and copyright holders additional tools to curb access to "rogue websites dedicated to infringing or counterfeit goods "”

In practice, it allow a complete site to be blocked, it is only required to have material that infringes copyright, that includes music, movies, images, text, etc.

It isn’t the first time we see proposals like this, in recent years companies have struggled videos and music piracy by any means. But this time I start to have fears.

In these last days do you tried to download something from megaupload? If yes, then you might have noticed that this site does not exist. It has been accused of copyright infringement and money laundering. Immediately a lot of discussion groups appeared on social networks, many government sites and supporter of SOPA have been suffered DDOS attacks (has you can see in this graph) and many large companies have marked her position against. But the fear is installed and other file hosts are turning off their services.

Currently this is the list of entities that are against

https://www.cdt.org/report/list-organizations-and-individuals-opposing-sopa

There is a huge list? I think so, but this gives me no guarantees...

Comments cannot be wrong, right? So I'll give my opinion, while it’s still allowed:

Actually the Internet is in an absolute chaos, probably the start of the first virtual world war to be more precise. Entities who want a free Internet on one side and the other people who do not know anything about computers, but are lucky enough to have anyone that see or hear the movies or music that their companies produce.

And in the midst of this, where are the software companies? On the side of free Internet, perhaps because they know something about computers and Internet...

Moreover, the USA has methods to control more than half of the Internet and think that is the capital of the world, of course those who think that way, should have watching to many American action movies or should have been born with a disorder named Anencephaly, in the case of the ones how agree with SOPA, I think that they haven’t watching movies…

I know it isn’t easy, but it is necessary to remove this control, the faster the better. My proposal is that

Be created a new DNS system, distributed, without a controlling entity, FREE and open source

Improve the backbone links between Europe, Russia and Asia, it will allow us to aid our American friends

Relocation of servers to outside of U.S. territory

Increase the protests as a way to awaken the world to the current problem

And above all, force these people that make those ridiculous proposals to do an introductory computer course.

I hope you enjoyed my long opinion, wish that in a short time I could write something better :P

Using grep command

2011-12-29T17:12:00.000-08:00

Let's talk about something used by some users of Linux that handle large amounts of information, the grep command.
This command lets you search for occurrences of text or expressions in a file or stdin, excellent links to search, numbers, IPs and other elements in large log files.

Its syntax is
grep [OPTION] ... PATTERN [FILE]

and usually the most used options are
-E (use extended regular expression
-i (ignore case)
-v (show only non-matching occurrences)
-o (show only the part of the line matching)

Now as an example, we use the following template file "test.txt"

123
test
192.168.0.1
192.168.300.0
something.168.0.0
let's put some numbers too 123456 done!
http://hackedprojects.blogspot.com
mymail@provider.com
see my blog in http://hackedprojects.blogspot.com but don't send anything to mymail@provider.com because it isn't my mail address
:)
<a href="http://www.google.com/">Google</a>

And now a set of commands used frequently (at least by me)

grep "[0-9]" teste.txt

Show everything with numbers (line 1,3,4,5,6)

grep "[^0-9]" teste.txt

Shows anything that hasn't just numbers (every line except 1)

grep "^[^0-9]" teste.txt

Show everything that doesn't start with numbers (every line except 1,3,4)

grep -E -o "[a-zA-Z0-9.-]+@[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+" teste.txt

Get every email address, note the -E and -o arguments, they are important. I can't guarantee that this expression will work with all mail, however there are many more expressions, some more effective than others

grep "[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}" teste.txt

Get any ip address, without number range validation (line 3 and 4)

grep "$[^\.]\|^$$[0-9]\{1,2\}\|1[0-9]\{2\}\|2[0-4][0-9]\|25[0-5]$\.$[0-9]\{1,2\}\|1[0-9]\{2\}\|2[0-4][0-9]\|25[0-5]$\.$[0-9]\{1,2\}\|1[0-9]\{2\}\|2[0-4][0-9]\|25[0-5]$\.$[0-9]\{1,2\}\|1[0-9]\{2\}\|2[0-4][0-9]\|25[0-5]$$[^\.]\|$$" teste.txt

Get any ip address with number range validation (line 3)
Credits goes to a user in http://superuser.com/questions/202818/match-ip-address, I only merge it in one expression

grep -o "$ftp\|http\|https$://.*\..[^\ \"'<>]*" teste.txt

Return only urls starting with ftp, http or https (line 7 and url from line 9)

grep -o "http://[^\ \"'<>]*" teste.txt

Same as the last expression, but simpler and only work with http

You can use logic too

OR: grep "192\|123" teste.txt
Returns line 1,3,4 and 6

AND: grep "192" teste.txt | grep "300"
Returns line 4

NOT: grep -v "192" teste.txt
Returns every line except 3 and 4

That's all for now, time to continue working, see you later :)

Quick way to encrypt your objects in Java

2011-12-29T11:05:00.000-08:00

Hi, hope you have a good Christmas :) Mine was not bad, but here I am to write a little more.
Besides eating chocolates, these days I have continued some of my school works. One in specific is a game for android, that soon I will talk more in detail.

One important thing in games is the possibility of save the scores in a way that no one can forge, at least directly. So how do this in Java?

The simplest idea that I remembered was to put the scores in a particular class, make it serializable, apply a xor and write it to a file, to recover do the reverse process.

So this is our class

class Person implements Serializable{
 String name;
 int age;
 public Person(String name, int age) {
  this.name = name;
  this.age = age;
 }
 public String getName() {
  return name;
 }
 public int getAge() {
  return age;
 } 
}

In this example, our key will be 10

byte key=10;

To convert from object to array and from array to object, we will use these two functions

public static byte[] object2Bytes(Object object) {
 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 try {
  ObjectOutputStream oos = new ObjectOutputStream(baos);
  oos.writeObject(object);
 } catch (IOException ioe) {}
 return baos.toByteArray();
}

public static Object bytes2Object(byte[] bytes){ 
  Object object = null; 
  try{ 
   object = new ObjectInputStream(new ByteArrayInputStream(bytes)).readObject(); 
  }catch(Exception e){} 
  return object; 
}

And finally the main code

public static void main(String[] args) {
 Person person = new Person("asd", 10);
 
 byte []dataArray;
 byte key=10;
 
 try {
  FileOutputStream fos = new FileOutputStream("file.dat");
  dataArray=object2Bytes(person);
  for (int i = 0; i < dataArray.length; i++) {
   dataArray[i]=(byte) (dataArray[i]^key);
  }
  fos.write(dataArray);
  fos.close();
 } catch (Exception e) {
  e.printStackTrace();
 } 
 
 dataArray=new byte[512];
 try {
  FileInputStream fis = new FileInputStream("file.dat");
  fis.read(dataArray);
  fis.close();
 } catch (Exception e) {
  e.printStackTrace();
 }
 
 for (int i = 0; i < dataArray.length; i++) {
  dataArray[i]=(byte) (dataArray[i]^key);
 }
 Person person2 = (Person) bytes2Object(dataArray);
 System.out.println(person2.getName()+" "+person2.getAge());  
}

The output that you get is "asd 10"

But now let's take a look in the file "file.dat", first without encryption

Note the "asd" name and "0a" age (10 in hexadecimal) near the end

and now with encryption

As you can see, something so simple and that is done in 5 minutes, can get away the more newbies. Obviously, something as simple is far from secure, the ideal is to use a larger key and use some algorithm really safe.

Which you like this idea :)

Choosing good passwords

2011-12-21T17:56:00.000-08:00

My schoolwork is finally going well, so today I will take a break from works and everything related to programming.

Let's talk about something we use every day: passwords.

Even I who use computers for many years, sometimes I make mistakes. One of those led to one of my hotmail account to be hacked, and that happened precisely to the account that I use less and where I was using just two simple words found in the dictionary. Fortunately all ended well, but it isn't always the case ... so I prepared some tips that sometime we don't remember.

Don't use the same password in every sites/machines
If you can, use diferent usernames/mails too
Avoid passwords that contains personal information (last name, birth date, etc)
Avoid short passwords (8 characters is the absolute minimum)
Change your passwords every months
Don't use patterns or sequential numbers (qwerty, asd, 1234, 123123)
Don't use repeated characters (aajj11)
Simply don't use any word from the dictionary without any transformation
Include punctuation and numbers
Use uppercase, lowercase and other symbols too
Replace letters with equivalent numbers ('I love pizza' for '1.l0v3.p1zz4')
Make jokes with your keyboard layout and combine with other text ('1qazZAQ!+H3110w0r1d')
If you have problems remembering your passwords, write them in paper and put them in any safe place (your wallet/monitor isn't safe place)
Use a second stage authentication (Google have one and probably your bank too)
And my favorite, DON'T share your password with your new “love of your life” that you just met 30 minutes ago as a proof of confidence and (put your ~~useless~~ reasons here).

Finally I also recommend using an online password generator:

http://www.pctools.com/guides/password/
http://strongpasswordgenerator.com/
http://www.freepasswordgenerator.com/

Now have fun securing your passwords while I have fun playing some games :P

Tips to help you choose your Linux distribution

2011-12-16T16:22:00.000-08:00

In the last three days I have been programming in android since I get up until I go to bed, so the last thing I want to see now is Java. For that reason I'll talk about another topic: Linux distributions.

As it happened to me, anyone who wants to move from Windows to Linux will face her first difficulty, choosing between a big number of distributions.

But what is a distribution?

Just like in windows family, you have Windows 9x, NT and CE, and for each of them, you have versions (as: 95,98,ME). In Linux it isn’t so different, with the particularity that the core (kernel) are the same.

So what’s the difference?

In Windows you have a company with total control over the core, applications and interface that the operating system will have, the final user may change something, but not as much as he may want.

In Linux anyone could grab the kernel, append a bunch of applications, tweak some parameters and puff, there’s a new distribution!

The freedom offered by Linux can look very good, but it isn’t always. This leads beginners to get confused and to have a fragmentation of the “help content”. Even worse is the fact that normally for the same thing there are at least two alternatives, both with their flaws and both have their qualities.

So I'll give some tips to help you choose one, and facilitate your entry into the magic of Linux

1 - Linux is not Windows, stop fooling ourselves, do not choose a distribution similar to Windows just for that reason.

2 - Remember that README file in windows that usually nobody reads? In Linux it is really necessary, forget the "next, next, next, finish"

3 - Stay away of mini distributions, usually they lack a really needed set of programs and it becomes harder to find support.

4 - I hate to say that, but if you don’t have an Internet connection and you aren’t an computer expert, Linux is not for you, for now...

5 - That console gives you fear? Don’t have, it isn’t so complex as it sounds and often lets you do more and better than with the GUI

6 - Do not be afraid of trying new distros, eventually you will change

7 - Do not give up just because on Windows you do it in seconds and on Linux you need to look for tutorials, nobody is born knowing everything.

And now some names…

Are you a perfect beginner in Linux? Ubuntu is for you.

Do you know how to make partitions in Linux? openSuSE, Debian or Fedora

Do you use a netbook? For me a netbook is a laptop with less resources, so… openSuse

Do you really know how to use Linux? Slackware, Gentoo or Arch (or other if you like)

To conclude here I leave some links that may be useful to help you decide

http://www.zegeniestudios.net/ldc/

http://polishlinux.org/choose/comparison/

http://www.phoronix.com/scan.php?page=article&item=linux_2010_fiveway&num=1

Saving files to External Storage in Android

2011-12-16T09:08:00.000-08:00

Just a snippet of code for android that can help some of my friends.

String FILENAME = "myfile.txt";
boolean externalStorageMounted = false;
boolean externalStorageWriteable = false;
String state = Environment.getExternalStorageState();

if (Environment.MEDIA_MOUNTED.equals(state)) {
 externalStorageMounted = true;
 externalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
 externalStorageMounted = true;
 externalStorageWriteable = false;
} else {
 externalStorageMounted = false;
 externalStorageWriteable = false;
}

if (externalStorageMounted && externalStorageWriteable) {
 File dbfile = new File(Environment.getExternalStorageDirectory(), FILENAME);
 FileOutputStream fos = new FileOutputStream(dbfile, true);
 //Do anything with fos
 try {
  if (fos != null)
   fos.close();
 } catch (IOException e) {
  e.printStackTrace();
 }
}

Ok, almost done, but not yet.Open your AndroidManifest.xml and add the following line

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

or using graphical interface: Permissions -> Add... -> android.permission.WRITE_EXTERNAL_STORAGE

And everything ready.

2011-12-14T22:04:00.000-08:00

Recently a friend of mine told me about an attempt to put Android 4.0 on Samsung GT540, it seemed too unrealistic but it is perfectly true, here is the link to the blog of the person who is attempting such a feat.

http://aosp.mikegapinski.cba.pl/?page_id=14

And to give a special touch, a video too.

If someone wants to try, do not forget to leave some feedback about this experience :)

Downloading files in Java via HTTP

2011-12-13T17:41:00.001-08:00

Today a friend of mine asked me a small piece of code for an Android application that allows downloading a file via HTTP from a remote server and save it to a local file. I looked in my documents and quickly found a small download manager that did precisely that.
But now I will share with you a class in Java (android or not) that takes as argument a URL and the destination file and download it. Remember that this code is very basic and is only to give ideas.

public class DownloaderClass {
    public void downloadFile(URL url, File outputFile) {
        int BUFFER_SIZE = 4096;
       
        InputStream in = null;
        FileOutputStream fos = null;
       
        try {
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.connect();

            if (conn.getResponseCode() / 100 != 2) {
                throw new RuntimeException("Response Code: " + conn.getResponseCode());
            }
           
            in = conn.getInputStream();
            fos = new FileOutputStream(outputFile);

            byte data[] = new byte[BUFFER_SIZE];
            int numRead;
            while (((numRead = in.read(data)) != -1)) {
                fos.write(data, 0, numRead);
            }
        } catch (IOException e) {
            System.out.println(e);
        } finally {
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                }
            }

            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                }
            }
        }
    }
}

To use it, you just need 2 lines of code in your main.

DownloaderClass dc = new DownloaderClass();
dc.downloadFile(new URL("http://hackedprojects.blogspot.com/favicon.ico"),new File("c:\\favicon.ico"));

As you can see, it's simples :P

Man dies electrocuted while stealing copper cables

2011-12-13T03:59:00.000-08:00

Generally I don’t care about daily news, but today I’ll make an exception.
In the last days I've heard news about stolen goods, from diesel from cars to money from the kindergarten‘s Christmas tree, all of them has been a success for the thieves, except that one:

(Portuguese) http://sicnoticias.sapo.pt/Lusa/2011/12/10/almancil-homem-morre-eletrocutado-autoridades-suspeitam-de-tentativa-de-furto-de-cobre

(English) http://translate.google.com/translate?sl=pt&tl=en&js=n&prev=_t&hl=pt-PT&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fsicnoticias.sapo.pt%2FLusa%2F2011%2F12%2F10%2Falmancil-homem-morre-eletrocutado-autoridades-suspeitam-de-tentativa-de-furto-de-cobre

It appears to be an “usual” case of the thief that had a really bad day, but no, I have seen it on TV and I’ll explain why.

That pole is in fact an electricity pole of middle tension, let's say…between 3000V and 60000V, as you can see, it appears to be kind of dangerous and requires extreme caution and proper equipment.

Now you may ask, what equipment? I don’t know about you, but I prefer to be right in front of my computer writing and launching of that creature, but if I REALLY need to be there, at least I would wear high voltage gloves!

However not everyone thinks this way, besides he doesn’t know what are high voltage gloves, he had the courage to try to cut the cables with this:

At least someone freed him of his misery…

So what did you learned from this? I learned that if I remember to steal cables from a pole of middle or high voltage without gloves and with a garden shears, I can’t forget to bring a rope, so people will think I tried to commit suicide instead of having a death so stupid and humiliating like this.

Read text file line-by-line in Java

2011-12-13T03:49:00.000-08:00

I know that it's simple, but I'll leave it here.

DataInputStream dis = null;
try {
   dis = new DataInputStream(new FileInputStream("file.txt"));
   BufferedReader br = new BufferedReader(new InputStreamReader(dis));
   String line;
   while ((line = br.readLine()) != null) {
      System.out.println(line);
   }
} catch (Exception e) {
   System.err.println(e.getMessage());
}finally{
   try {
      dis.close();
   } catch (IOException ex) {}
}

Data types conversions in java

2011-12-13T03:34:00.000-08:00

In the last weeks I've been programming in Java for 2 school works and others 3 more projects, I'm the type of person how prefer thing more low-level, so I can say that I never used it so much in so little time. The good thing about that is that I'm finally learning many things about objects and events, it's just like a new world.

So I have been taking notes and I'll share a little about a thing that I always forget, how to convert between data types commonly used.

	byte	short	int	long	float
Byte	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Short	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Integer	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Long	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Float	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Double	byteValue()	shortValue()	intValue()	longValue()	floatValue()
Boolean	(byte) ((a)?1:0)	(short) ((a)?1:0)	((a)?1:0)	(long) ((a)?1:0)	(float) ((a)?1:0)
String	Byte.parseByte(a)	Short.parseShort(a)	Integer.parseInt(a)	Long.parseLong(a)	Float.parseFloat(a)

	double	boolean	char	String
Byte	doubleValue()	!(compareTo(0)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Short	doubleValue()	!(compareTo(0)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Integer	doubleValue()	!(compareTo(0)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Long	doubleValue()	!(compareTo(0)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Float	doubleValue()	!(compareTo(0f)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Double	doubleValue()	!(compareTo(0.0)==0)	Character.forDigit(a,10)	String.ValueOf(a)
Boolean	(double) ((a)?1:0)	a	((a)?’T’:’F’)	String.ValueOf(a)
String	Double.parseDouble(a)	!(compareTo(“0”)==0)	a.charAt(0);	String.ValueOf(a)

This explains how to convert from classes for primitive types, on the left side are the original classes and on top are the primitive types. Of course there are other important things, but is already a good summary.

Hello World!

2011-12-12T20:24:00.000-08:00

Hi folks, I'm David Silva aka Longinus, a Portuguese computer science student and this is my new blog where I will publish some of my projects, notes, news, reviews and lot more about programming in C /C++, Java, Android and PHP, Linux, Robotics and Electronics. Wish you like and don't forget, leave some comments :P