Create a digital system that encodes a message into a media object, and also provides a means of decoding it. Your system should be designed to hide information in plain sight—within images, text, video, sound, or physical forms. Think carefully about the specific information your system is designed to encode, and the significance of the relationship between this information and the medium that contains it. You may choose to encode text, data, code, images, music, or other information of your choosing. Present one or more examples of your system in use. This assignment can be tailored to focus on steganography (the act of hiding a message in another medium) or cryptography (the act of encoding a message).
The advent of the written word created a need for secure communications, both for those in power and those who would oppose them. This need for secure messaging has long inspired techniques of cryptography, defined as the encoding of messages. Some historic cryptographic approaches rely on the use of pre-computational devices like the decoding wheel, the Polybius square, and the Enigma machine, while others use simple ciphers like the pigpen cipher, Morse code, Braille, or ROT13. For children, there can be a wholesome joy in exchanging secret messages with one's friends, and a thrill in the effort of unlocking and revealing them.
Steganography is the special cryptographic technique of concealing information within another media format. Early cryptographers like Sir Francis Bacon and William Friedman were fond of steganography, building systems to hide messages in music scores, photographs, and even flower arrangements. Digital technologies offer many possibilities for creative steganography. Unused pixels or bytes in files can be filled with invisible information, data can be transcoded into different media, and (as with acrostics) messages can be distributed across huge volumes of online communications.
The 2013 Snowden revelations confirmed that the US government was recording the online communications of the American public, and produced a collective realization that unencrypted communications across digital networks are inherently insecure. On the Internet, it is impossible to know if communications are intercepted, making the development of practical and reliable cryptographic technologies an ongoing urgent challenge.