MakeUseOf » cryptography

The Easiest Way To Send Secret Messages Within Pictures

Tim Lenahan — Thu, 26 Aug 2010 21:30:41 +0000

Have you ever heard of Steganography? Wikipedia defines it as “the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message…” This method of hiding secret messages in pictures has been around for many years but these days with computers and all that, the methods have become more attainable for the every day person.

One method of putting this art to use is to hide a message within an image. You can send messages to anyone you’d like to without anyone else being the wiser. This could also be used to put together games and puzzles for website visitors or blog readers by hiding messages in specific images allowing people to hunt for the messages. This isn’t the first time the art of steganography has debuted on MakeUseOf – Tina showcased a desktop client for Windows and Jackson wrote about iSteg for Mac; both of these apps can be used for the exact same purpose.

Whatever your reason for hiding secret messages in pictures, you can now do so regardless of your operating system — thanks to a web-based tool offered to us by mozaiq.

While being a site dedicating to helping people turn images into mosaics, if you head to a subdirectory on the site you will see they offer the ability to encrypt messages in images also.

The process is simple: upload an image, type a message, enter a password, click a button and download the image with the message encrypted in it. Sounds easy enough but let’s take a closer look.

Go to mozaiq.org/encrypt. When you do, you are immediately given the fields to begin the process. Off to the left there is an introduction to the art/science of steganography and mozaiq’s encrypting tool. To the left is where all of the action takes.

Choose a picture to upload. Make sure it us under 128KB or it won’t work. Once you have chosen the image, enter the message you would like to share.

Before you go and hit the “Hide Your Message!” button, you can enter a password to further protect the privacy of the message. This is optional and totally up to you.

Once you hit the magic button, you are able to download the image file. Notice that the image will only be available for download for 5 minutes making it imperative that you download it immediately.

Also realize that you can’t change the file in any way other than renaming it. This includes cropping, resizing or even converting it to another file extension. Once you download it, you are able to send it or post it anywhere you please. When you do, make sure the recipient knows to go to mozaiq.org/decrypt in order to see the message.

Try out this image for size:

Right-click and save the image of the cell phone and go to the decryption page. I gave it the password “hello” so you can see how it works. See if you can find out the encrypted message. I think you will find it to be both incredibly enlightening and not that surprising (seeing as though it’s also in one of the screenshots above).

So now that we have a way to hide secret messages in pictures, in a way that will not provoke attention, what ways can you think of to put it to use?

FreeOTFE Encrypts Files On Hard Drives, CD and USB Sticks

Stefan Neagu — Sun, 05 Apr 2009 15:01:18 +0000

These days, every one of use carries portable media like USB sticks, memory cards and optical media; it’s extremely easy to lose a device the size of your thumb and the consequences can be dire, especially if it sensitive corporate data. This also applies to more common situations; you could lose your dissertation or photos of your family. You can easily eliminate this threat by using encryption software.

FreeOTFE, is freeware file encryption software, which has its source code freely available. Its name comes from “˜On The Fly Encryption’, a procedure which automatically encrypts and decrypts information at the user’s demand, without the need for interaction with the application which manages the encryption layer “˜transparently’.

The main purpose of FreeOTFE is that it lets you create so called voumes/disks which operate exactly like a normal disk, with the exception that anything written to one of them is encrypted before being stored on your computer’s hard drive. No one except you can open and view those files. In order for someone to read the files on those encrypted volumes in the future the person will need to use FreeOTFE and know the password.

First released in 2004 by Sean Dean, FreeOTFE has an easy to use interface complete with a step-by-step wizard that helps you select settings for your encrypted volume, as well as a portable mode, which means you can access your encrypted files at any computer.

How To Use FreeOTFE To Hide and Encrypt Data

Creating a new encrypted volume is very simple.

If you’re not familiar with encryption modes and their respective abbreviations, you just need to select New and then click on Next.

Next specify whether the new volume should be created as a disk image file stored on your filesystem, or take up a disk partition/entire physical disk. For beginner users it’s recommended to go with disk image file stored on your filesystem option.

In the next steps you will be asked to select a size and a password for your volume file along with some other options that you can leave on default settings.

Finally, check everything and click on the Finish button to complete the wizard. At this point you will get your encrypted volume where you can add the files. The volume file has .vol extension and stored in the location indicated durng the volume setup wizard.

When you have created your first volume, FreeOTFE will automatically mount it as a disk on your PC, and you’ll be able to copy and remove files just like another hard drive. You should find it under ‘My Computer’.

Please note that you need to format it (via right-click menu) before you can open it and move the files there for the first time.

Once the volume is formatted you can start moving the files there. When you’re done, open the FreeOTFE and select the ‘Dismount’ option to hide the disk/volume. This will remove the volume from ‘My Computer’.

After you finished working with the files and dismounted the volume, you can copy that newly created volume file to any media, a CD, a USB stick, or a memory card and carry it with you wherever you go.

Whenever you want to access or edit files on the encrypted volume you will need FreeOTFE (or similar encryption program) and a password that you provided during the volume setup wizard. First open the FreeOTFE, then click on Mount, select the encrypted volume (.vol file) and enter the password. This will mount the file as a drive and add it to ‘My Computer’ window. (Note: Make sure to dismount the volume when you are done working with it)

You can also copy a portable version of FreeOTFE (from Tools> Copy FreeOTFE to USB drive) to access the files from a computer which doesn’t have FreeOTFE or another decryption program.

When you carry those encrypted volumes on a USB drive or a CD, you also have an option to open/mount volumes in read-only mode, which means your files won’t get infected if the computer you’re working on has malware.

Here are some of the most important aspects of FreeOTFE:

Hash algorithms: MD5, SHA-512, RIPEMD-160, Tiger and more.
Ciphers: AES (256 bit), Twofish (256 bit), Blowfish (448 bit), Serpent (256 bit) and more.
Cipher modes supported include XTS, LRW and CBC.
Windows Mobile compatibility.
Create standalone encrypted volumes or encrypt whole partitions/disks.

At the moment, the safest encryption mode is XTS, and I strongly recommend you use it instead of the others if you have very sensitive data, like social security numbers or bank account details.

The XTS proof yields strong security guarantees as long as the same key is not used to encrypt much more than 1 terabyte of data. -IEEE P1619

FreeOTFE is in many ways similar to True Crypt, which Mark O’Neil covered in detail. For more advanced users, there’s the IronKey, an USB stick built with security in mind.

I’d like to hear your experiences using encryption software and scenarios when encryption proved valuable.

You can save the extracted program on your hard drive and copy FreeOTFE afterwards to a CD using a burning application.

Become a Secret Steganographer: Hide and Encrypt your Files

Tina Sieber — Sat, 07 Jun 2008 14:37:01 +0000

While cryptography stands for encrypting or coding messages in a way that no one who doesn’t hold the key can understand them, steganography means hiding messages, so that no one who doesn’t know it’s there will realize it’s there in the first place. Naturally, both techniques are best used in combination, and the tool I’m showing you today applies to both cryptography and steganography.

It’s easy to understand why one would like to not only encrypt but also hide a message. Using encryption alone is suspicious, whether or not the message is of any interest or meaning. Once discovered, the message is in danger of being cracked by curious individuals or used against you in heated discussions. Thus, if you want to hide your secret passion to write trashy short stories from your significant other, don’t encrypt but hide the text in your notorious country music collection…for example. But seriously, steganography can prove very useful to safely store sensible information. Think of passwords, the birthdates of ex girlfriends, the phone number of George Clooney, your secret plans to take over world leadership or you name it. Earlier we did a quick post on how to hide your folders and files in Windows but the tool I am about to show you is more secure and harder to break.

The tool I will show you in detail is S-Tools. My little tutorial is going to be extremely short, since the program is so straight-forward and simple to use. S-Tools was originally written for Windows 95 by a guy called Andy Brown. It does run on Windows XP, but it looks like it’s slowly disappearing from the face of the internet, the available download sources appear somewhat obscure and the developer’s homepage is long gone. However, the source linked to above is safe.

With S-Tools you can hide information in BMP, GIF, or WAV files, and the resulting file will be BMP, GIF, or WAV, respectively. You can hide any file type and even multiple files, but to hide larger files also the host file needs to be of sufficient size. Note that the size a host file can hold is indicated in the bottom right corner of the program window.

So how does it work? Just drag the host file to be into the S-Tools window. Next drag the file you want to hide onto the host file, provide a passphrase, choose from the encryption algorithms IDEA, DES, Triple DES or MDC, hit OK, wait for the calculations to complete, then save the resulting file (right click and select Save or Save as…) , and you’re done. To extract hidden files, simply drag the respective host file into S-Tools, right click, select reveal, type in the passphrase, select the encryption algorithm, hit ok and voilÃ , a small archive revealing all hidden files will appear from where you can save the files.

Go ahead and try to crack this sound file or this image. What’s the hidden word? Need help? Highlight this text >>> MUO <<< for the passphrase and this text >>> IDEA <<< for the encryption algorithm.

Do you find this application useful? Do you know of other steganography tools? I’m looking forward to learning your opinion in the comments!

(By) This post was written by one of our regular authors, Tina from Recommended.