Date Added: Dec 2012
Information security is a fast growing research field which includes numerous problems in it. Partial image encryption is one of the important problems in the field of image information security. This paper describes the partial image encryption in two ways using hill cipher technique. First encryption technique uses two slightly different keys to construct two self-invertible matrices, which are used in two different stages to get partially encrypted image. Second encryption technique use one key to construct one self-invertible matrix and it is used in first stage. In second stage same key matrix along with few modification in diagonal values are used to construct another self-invertible matrix which leads to partial image encryption. Reverse process is employed to reconstruct the original image.