Steganography

   Photo Database application has cool feature - hidding data in images or steganography. The advantage of steganography, over cryptography alone, is that messages do not attract attention to themselves. Therefore, whereas cryptography protects the contents of a message, steganography can be said to protect both messages and communicating parties.

How to hide data in the program step by step - see here.

   Here is an example of steganography based on the test data. All attachments are protected by DES algorithm with password "123" without quotes.

   Two algorithms to hide data are supported: LSB and data hiding as part of a JPEG file. More details of each algorithm see below.

   LSB (Least Significant Bit) — The essence of this method is to replace the least significant bits in the container (images, audio or video) on the hidden message bits. The difference between empty and filled containers shouldn't be perceptible to human senses. For this algorithm, the greater the attachment size larger resolution of the image. See the table below with example images.

Original	Small attachment	Medium attachment	Big attachment (maximum for this image size)
JPEG, 252кб	PNG, 610кб	PNG, 623кб	PNG, 736кб
You can click on any image to enlarge or download	RFT, 4.7Кб	RFT, 13.0Кб	RFT, 80.5Кб

   Steganography using of the features of JPEG file format. This method can include the recording of information in the metadata or in various reserved fields of file. For JPEG files, "hidden" data is stored after the image data. The image does not change, and the file size is increased: original image size + data file size.

Original	With hidden PDF file
JPEG, 252кб	JPEG, 406кб
You can click on any image to enlarge or download	PDF, 351Кб

   You can encrypt image file with any other passowrd and other encryption method to increate protection.