Security in the cloud is the top most concern. To achieve trust and preserve the privacy of data stored in third-party cloud storage has emerged as a key research area. To achieve this, several different techniques have been proposed based on cryptography. Secret sharing schemes and chaos based encryption have also been considered to address these issues of trust and privacy by various researchers. In this paper, we are proposing a new scheme to encrypt the private and sensitive images of users in the third party storage named as "Securing images in cloud using hyper chaos with user authentication" to solve the problem of authenticating users. Chaos based encryption with image captcha authentication using VCS is a major advantage of this scheme. Chaos based encryption is a very secure method for encryption. Many researchers have used the above technique but user authentication or authorization is not mentioned in their schemes. To increase more security we have included the authentication in the scheme. In this paper the authentication process is explored in depth and only the overview of encryption process is given. For securing the authentication logistic map is used to divide and shuffle the original image captcha into many blocks. The use of visual cryptography technique is explored to preserve the privacy of image captcha. Part of the image share will be kept with the image owner such that the original image captcha can be revealed only when both (user, owner) of the shares are simultaneously available. The individual share images do not reveal the identity of the original image captcha. Once the original image captcha is revealed after merging different shares, the user will be considered as authenticated user. Then only the encrypted key for the images will be transferred to the user. Dynamically generating the Captcha image by the system is one of the major advantage of the system.

Cloud security Images Visual cryptography Captcha Logistic map