What is LSB steganography?

LSB stands for least significant bit, the last bit of each color value. Changing it moves a color by just one step out of 255, which nobody can see. By using the last bit of many pixels in a row, a whole message or even a file can be hidden inside an ordinary looking picture.

To read it, you need to know which colors were used, which bit, which direction the pixels were read in, and the order of the bits. CacheCrack tries around 100 combinations at once, like the zsteg tool: one, two or four bits from each color, the red, green, blue and alpha channels in several orders, the top bit as well as the bottom ones, and both directions through the picture. It lists any that produce readable text or a hidden file, like a ZIP, which you can download. Click one to see the whole message, or turn off "Try common settings" to choose your own.

Use the original file

This only works on lossless images like PNG, BMP and GIF. JPEG compression and resizing scramble the low bits, so a message will not survive being saved as a JPEG or uploaded somewhere that shrinks the image.