Steganography is a secret communication to hide the secret data. It is an invisible communication that hides data. The secret message is inserted into the image files. The image files can use stego-key to hide the data and the resultant image is called as stego-image. This is most important for the internet users to share their secret data in an efficient manner.
In image steganography, security is very important. To get the good security, some methods combine steganography and cryptography. By combining both methods, the capacity of secret messages is very limited. There is trade off between capacity and security. The more secure messages, the less capacity of messages.
We proposed novel method that combining RSA and horse step algorithm. Horse step algorithm is an algorithm that encrypts data spacially by exploiting 2 d matrix. By combining RSA and horse step algorithm, we obtain more capacity (8.6 - 45 % more than previous method) but keep secret message as secure as RSA algorithm.