In the modern world of advanced cryptography, steganography is rarely used alone (as far as we know!) in important modern roles – but is often combined with cryptography in communication. However, there are several areas where steganography continues to play a very important role.
Steganography is still often used for uniqueness and validation purposes, such as storing data without it being obvious the data is stored there.
For example, almost all modern laser printers now print a series of barely visible yellow dots on every page printed. These dots, when interpreted properly, contain a variety of meta data about the print job, such as the date and time, printer model, and serial numbers.
Steganographic messages are also commonly hidden inside of digital media – often images or audio. The reason being is that, even if suspected, they are very hard to detect as there are plentiful different ways they could be implemented. For example, a bitmap image may have 8 bits representing each of the three color values (red, green, and blue) for each pixel. If we consider just the blue there will be 8 binary bits for the amount of blue in that particular pixel. The difference between 11111111 and 11111110 in the value for blue intensity is likely to be undetectable by the human eye. If we modify the least significant bit (the last bit) in each byte for each color, that gives of potentially hundreds of bytes of information storage, and yet the overall appearance of the image will remain unchanged.