Increased use of internet demands substantial protection for secret image file from any adversary, specifically during transmission. In the field of cryptography there are two role models: cryptographer and crypt-analyst/attacker. The cryptographer develops techniques to make sure certain safety and security for transmissions while the crypt-analyst attempts to undo the former’s work by cracking the same. The basic goal of our scheme is to design an image encryption model which is extra challenging against any attack. In our research article, we have introduced session key dependent image encryption technique wherein the session key is the function of an original secret key (known for a pair of sender and receiver one time forever at the beginning) and the present secret image to be encrypted. Additionally the scheme does not require extracting and remembering of session keys to construct the subsequent session keys although the keys change during each transmission. Besides, in our scheme a double encryption technique is required, which once again confirms that the technique we propose is more robust than the conventional image encryption techniques known till date and is capable of resisting cyber-attacks of such kinds.