A New Symmetric Key Encryption Algorithm Using Images as Secret Keys

Symmetric key cryptography is a common cryptographic technique using the same key at both the transmitter and receiver side. The main advantage of symmetric key encryption is its less computational cost compared to its counterpart-public key encryption. In this work a new symmetric key encryption scheme is proposed. Rather than using normal binary secret keys, our technique uses images as secret keys. Message letters are converted into their corresponding 8-bit binary codes. These 8-bit codes are scanned for image pixel values which are represented by the same 8-bit codes. When a match is found between the message 8-bit code and pixel values codes that location of the pixel is saved in a separate file. Instead of saving pixel locations as (x, y) coordinates, their locations are saved as one value column wise. After having all matches, pixels locations are transmitted as cipher text. The receiver side will scan the same image for those locations and will pick values at those locations which represent message codes. The main advantage of this scheme is its high security as its key size is very large.