Software :: Encryption :: ImageCoder
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Description
Encrypt text into a "known" image.
Releases

VersionDateDownloadRegisterDescription
1.0.0 09/21/2005 Mac Win Free! Initial release.


How It Works
This program uses steganography, which is the science of writing a hidden message which is undetectable and indecipherable to all except the intended recipient. In this case, the message is hidden inside an image file. More specifically, the color of several pixels are tinted in a certain pattern. This pattern is a binary representation of the message, where 0 is represented by no change in the pixel's color, and 1 is represented by a small (invisible to the naked eye) color change of the pixel. This pattern is read left to right, top to bottom, like english.

Message Constraints
The length of the message may not exceed the width of the image times the height of the image divided by eight:
Message_Length <= (Image_Width * Image_Height) / 8
The message is terminated by a NULL character (0x00), so the message itself cannot contain such a character. In order to share a message containing binary data (characters not representable in ASCII), you can first encode your message into hexadecimal.

Image Constraints
The source image can be any format readable by the program. Some accepted formats are: JPG, GIF, BMP, PNG, PIC, PSD. The output file format will be determined by your operating system. On Windows, the output format is BMP. On Macintosh, the output format is PIC. You can convert the image to any format that is not "loss-full". JPG is loss-full, so do NOT convert the output image to JPG! Any image format with less than 32-bit color will be loss-full, so do not reduce the color depth! Also, it might be worth mentioning that changing the size of the picture will obviously corrupt the data.

Using the Interface
If you have a message you would like to encode, pick some image that the recipient will recognize and be able to acquire. Download that image to your hard drive. In ImageCoder, select "New" from the "File" menu. Type or paste your message. Select "Encode..." from the "File" menu. You will be prompted to choose the image you picked earlier, so locate it on your hard drive. You will then be asked where to save the encoded image. Now, place the encoded image somewhere your recipient can access it. Nobody will ever suspect that a secret message is hidden inside the image!

To decode an image, select "Decode..." from the "File" menu. You will be prompted for the original image, as well as the encoded image. The hidden message will appear in the window!

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