Extended Proactive Secret Sharing using Matrix Projection Method

Proactive Secret Sharing Scheme (PSSS) is a method to periodically renew n secret shares in a (k, n) threshold-based Secret Sharing Scheme without modifying the secret or reconstructing the secret to reproduce new shares. Given enough time, a hacker may be able to compromise enough shares (k or more) to gain the secret. PSSS is a scheme that allows generating new set of shares for the same secret from the old shares without reconstructing the secret. Using PSSS, all the shares are refreshed so that old shares become useless. Thus, an adversary has to gather at least k shares between two executions of PSSS. The secret remains confidential if fewer than k shares were compromised from the start of one PSSS to the end of the next PSSS. In this paper proactive secret sharing scheme for images is proposed based on matrix projection method. The proposed scheme provides the extended capabilities of enrolling and disenrolling of shareholders in the existing scheme. Also in the proposed scheme public information is shared with the participant’s shares which makes the scheme more reliable.