One method for doing this on on 8 by 8 blocks of canonical gray coding is bit plane complexity  segmentation. Gustavus Simons introduced the Prisoner's Problem to study this action. A simple digital  method for doing this is least significant bit insertion. Gerolamo Cardano developed a grille of rectangular  holes in paper for doing this. This act takes its name from a three volume work on communicating with  supernatural beings by Trithemius. OpenPuff is a program for doing the "deniable" form of this practice  using many different file formats. This practice is similar to Rivest's chaffing and winnowing, but unlike 
One method for doing this on on 8 by 8 blocks of canonical gray coding is bit plane complexity  segmentation. Gustavus Simons introduced the Prisoner's Problem to study this action. A simple digital  method for doing this is least significant bit insertion. Gerolamo Cardano developed a grille of rectangular  holes in paper for doing this. This act takes its name from a three volume work on communicating with  supernatural beings by Trithemius. OpenPuff is a program for doing the "deniable" form of this practice  using many different file formats. This practice is similar to Rivest's chaffing and winnowing, but unlike c&w  the adversary in this case will not know this is happening. One physical way to do this is microdots. This includes  jargon codes and semagrams are a form of this based on images or typography. Invisible watermarking is a form of  this action. For 10 points, name this act of hiding a message in a picture or text.
One method for doing this on on 8 by 8 blocks of canonical gray coding is bit plane complexity  segmentation.
steganography [prompt on hidden messages]