Steganography (hiding files inside photos) is one of the oldest yet effective technique which is used to send secret messages. Even though this technique is very useful, many don’t use it because the process involved is not so easy, until recently. But with advancement in technologies and softwares, now we have many easy-to-use softwares which does the job for us, like Hide In Pictures. Before introducing these softwares to you, let us see how Steganography works.
How Steganography Works?
Cover-Image is a JPEG file and is very important file in Steganography technique. It’ll pretend to be JPEG file, even when opened in a graphics application. Beneath this cover image you’ll hide other file, like another photo, encrypted files, a letter to your beloved one etc. Steganography when combined with Cryptography is much more powerful than Steganography itself. But, in order to create encrypted files we should use the softwares which are built for that purpose, like TrueCrypt etc. Encrypt the hidden file using your favorite software and then integrate it into an ordinary image which doesn’t look interesting. Steganography is not meant to obscure the message, but to obscure the fact that there is a hidden message.
Cover-Image + Hidden Data + Stego-key = Stego-Object
Some methods are used in Steganography :
- Substitution : Known as LSB (Replaces the last bit in a byte) is a simple approach to hide data in an image file but does not go well with file changing.
- Injection : Embedding the data in the carrier image, the disadvantage is that the output file size is huge.
- Generation of a new file : The Advantage for this method is that there is no original file to compare with.
Several factors are to be considered to judge the steganography method:
- Capacity: How much data can be hidden.
- Robustness: Unaltered despite compression or other common modifications
- Un-detectability: Inability for a computer to differentiate between covers and stego-objects
- Signal to noise ratio (PSNR): Calculates errors in the file relative to the original
- Invisibility: Inability for humans to detect a distortion in the stego-object
Some can recognize if a picture is used to hide some message, you look to some bits per pixel for high frequency noise. If you find it you might have a secret message.
Free Softwares to implement Steganography :
Free file Camouflage : This portable software is dedicated for this purpose, hiding files behind JPEG pictures. This software is licensed as donationware. A small delay is shown upon launching the free version and this can be eliminated by making a small donation. This Camouflage software fits seamlessly into the Windows context menu under Send To option of Windows File Explorer and allows to include a file that you want to hide in JPEG image.
I did some tests on files like EXE, JPEG, TXT, Word Files, AVI etc, and all the files remained fully operational in their original format : The JPEG image obtained after camouflage is displayed by any viewer. For more security, it offers password protection too.
Download : Free File Camouflage
Camouflage : Although this software is no more actively developed, it can be installed on Windows 7. This small program will hide the file you want (image, video, Word, Music etc…) in a JPEG file. The hidden content will revealed by you or the person whom you allow it, by providing the password with which you encrypted the file.
After installing Camouflage you will find two new context menu options in Windows Explorer : ‘Camouflage’ and ‘Uncamouflage’. User can also choose other names for Camouflage and Uncamouflage to make it more personal or less eye catching. Checking ‘Make camouflaged files Read-Only’, all files created by Camouflage have their Read-Only attribute set by default. This is highly recommended and it prevents the camouflaged file from being modified by certain applications when you open it.
Download : Camouflage
Hide in Pictures : This is also a free portable software. It recommends GIF or BMP images for encryption, and lets you set a password to retrieve the hidden file. While testing, I tried to embed the same Movie/PDF file which I used to test above softwares. But I got the error message telling that the size of the file was big. Then tried a small Text file which was accepted.
Download : Hide in Pictures
Maznik 2 : The interface of this software is simple. You’ll able to hide secret messages inside 24bit picture file (BMP is allowed, and JPEG failed) and then save that 24bit picture file with plain or ciphered text randomly distributed with in the picture.
Download : Maznik
Steps are being made towards steganography that relies on the key for its security but not on the method used to do so. A message sent in secret (steganography) with encryption (cryptography) is much more secure and stronger than when they are separate.