Steganography as a Windows 8.1 RT (metro) app.
Hide your secret-eyes-only text in pictures!
Steganography is the art and science of hiding information by embedding messages within others. Steganography works by replacing bits of useless or unused data in a picture with bits of different, invisible information.
This “unused data” are the least significant bits (LSBs) in the image pixels. The LSB is the bit that when flipped from 0 to 1 or from 1 to 0, then no significant change will occur on the total value; meaning no (optical) significant change will occur to the picture.
There are other apps that claim to provide Steganography while in fact they don’t! Those apps simply create a large file, containg the picture at position 1 followed by one or more files. Such pseudo-steganography can be easily de-coded. In fact, that’s nothing more than a ZIP file (without compression) 🙂
Size of Hidden Text
Assume that the image is 1000 pixels width by 800 pixels height, then we’ll have 1000 x 800 x 3 = 2.400.000 LSBs. The pixels are multiplied by 3 because each pixel has 3 elements (red, green, blue). And as each character of our message to hide can be represented by 8 bits, then that image can hide 2.400.000 / 8 = 300.000 characters!
The picture containing the hidden message will be saved as an PNG image. JPEG is a lossy format. The pixels and the hidden data would be be significantly altered when saving as JPEG. This would result in an “disturbed” image.