The word steganography is derived from the greek and can be translated as hidden text. It is a technique that allows to hide a secret message inside a container, such as a digital image. For which at first appearance the container does not raise any suspicion, as it is in effect an image respectively. The strength of steganography is this: the hidden message is there but not seen!
Steganographia is an application that allows you to hide (this is known as encoding) text (in ASCII format) within JPEG images, the most famous and popular web graphic format, and read them later (operation called decoding). The algorithm of Steganographia ensures a certain degree of robustness, ie the message is still decodable even if the image is recompressed (such as occurs for the images published on Facebook or Twitter). Steganographia has 8 different levels of robustness, the first level is less robust and therefore any recompression of the image can damage the hidden message, instead of level 8 is the most robust and more resistant to a recompression of the image. As you might guess the higher the level of robustness used the greater the degradation of the image.
In addition you can further protect the information with an encryption key, so who is in possession of the image to read the hidden message must also be in possession of the key.
With Steganographia you can directly send the image to Facebook, Twitter, attached to an email, or save it in the photo gallery of the device.
It is also possible to set a numeric password that will be required at application launch.
Steganographia is useful to hide and protect sensitive information that you do not want others to read, or you can post pictures in the most popular social networks, and only your friends or acquaintances can read the hidden message, first downloading the image to photo gallery of device and then through the use of Steganographia.
NOTES: as is well known the JPEG format is a lossy compression standard graphic files, which means that, to decrease the size of the image, the pixels less perceptible are eliminated, then be reconstructed not exactly the same in the decompression step. Then the integrity of the message depends both on the type of the image and the level of compression (quality), if the compression is too high (low quality) then also the maximum level of robustness can not be sufficient to preserve the message.
DISCLAIMER: anything that is hidden in an image is done at your own risk and it is your choice, the author of the software can not be held responsible in any way.