Steganography is the science with the help of which secret or confidential data is hidden within any media like text, images, audio or video and protocol-based network. As privacy concerns continue to develop, it is in widespread use because it enables to hide the secret data in cover images. Steganographic techniques are best suited for digital image processing. In general, Steganography is classified into spatial and transform domain techniques. This paper presents a new RGB based algorithm in spatial domain called Prime Pixel Alternation technique. In the present scenario, many spatial domain algorithms like LSB, first component alternate, pixel indicator are usually used for steganography since they are easier to implement and less complex. Even though their hiding capacity is high, they are more prone to steganalysis. A new RGB-based algorithm is designed to store data in Random prime numbered multiple pixel locations and the encrypted key is also stored along with the data in a co-prime location (co-prime to the aforesaid 3 numbers). This algorithm requires to choose 3 random numbers to store data in R(Red), G(Green) and B(Blue) components of the cover image(24 bit image). Blue component is given the priority to store more data (lowest prime no: multiple pixel location) because a research was conducted by Hecht [14], which reveals that the blue objects, if visually perceived, are intense and are comparatively less distinct than the red and green objects. Since the key size is fixed, it is stored in coprime pixel locations, which will be least in number. Key bits will be stored in R, G, B components one at a time in a cyclic manner, in the above mentioned co-prime locations, in which the security is improved. A null terminator bit pattern may be used to indicate end of key or data. The reverse process of the encoding algorithm is used to decode the message.
