Proposal of a cryptography method using gray scale digital images

In a world connected through a myriad of communication media, such as mobile phones and the Internet, it is extremely important that confidential information that travels across public networks reaches its destination with privacy preserved. This paper proposes a new method for data encryption using images that explore the random spatial distribution of pixel gray levels of an image. For the method test, text messages were made in Portuguese. Although the encrypted message sizes obtained with the proposed method are larger than the corresponding sizes obtained with other traditional methods, such as AES and RSA, the proposed method has the advantage of generating a different encrypted file each time it is used to encrypt the same message.