A. Sreekumar

V. P. Binu, A. Sreekumar

Secret sharing is a new alternative for outsourcing data in a secure way.It avoids the need for time consuming encryption decryption process and also the complexity involved in key management.The data must also be protected from untrusted cloud service providers.Secret sharing based solution provides secure information dispersal by making shares of the original data and distribute them among different servers.Data from the threshold number of servers can be used to reconstruct the original data.It is often impractical to distribute data among large number of servers.We have to achieve a trade off between security and efficiency.An optimal choice is to use a $(2,3)$ or $(2,4)$ threshold secret sharing scheme, where the data are distributed as shares among three or four servers and shares from any two can be used to construct the original data.This provides both security,reliability and efficiency.We propose some efficient and easy to implement secret sharing schemes in this regard based on number theory and bitwise XOR.These schemes are also suitable for secure sharing of images.Secret image sharing based on Shamir's schemes are lossy and involves complicated Lagrange interpolation.So the proposed scheme can also be effectively utilized for lossless sharing of secret images.

V. P. Binu, A. Sreekumar

Secret image sharing deals with splitting confidential images into several shares and the original image can be reconstructed from the qualified subset of the shares. Secret sharing schemes are used in transmission and storage of private medical images and military secrets. Increased confidentiality and availability are the major achievements. We propose an efficient (2, 2) scheme and (2, 3) scheme for secret image sharing. The scheme is lossless and also the share size is same as the secret size. The sharing and revealing phase uses simple modular arithmetic which can be very easily implemented. Experimental results on Binary and Gray scale images show that the proposed scheme is secure and efficient.

V. P. Binu, A. Sreekumar

Multi-secret sharing is an extension of secret sharing technique where several secrets are shared between the participants, each according to a specified access structure. The secrets can be reconstructed according to the access structure by participants using their private shares.Each participant has to hold a single share, additional information are made available in a public bulletin board.The scheme is computationally efficient and also each participant can verify the shares of the other participants and also the reconstructed secret.The scheme does not need any secure channel also.