On Secret Sharing Schemes with Extended Capabilities

Secret sharing allows split control over the secret. Secret parts known as secret shares are distributed to different shareholders (locations). Secret can be recovered upon combination of sufficient number of shares. Research into theoretical foundations, development of widespread applications, as well as, new attacks resulted in great need for extra features of existing schemes. We describe extended capabilities for secret sharing schemes. List of discussed issues contains (but is not limited to): multiple and different size sets of shareholders, schemes activation, multisecret schemes, cheating detection, secret shares renewal/maintaince, missing shares recovery. Next, research results into extended capabilities for Karin-Green-Hellman scheme are presented. We concentrate on Proactive Secret Sharing (PSS) and Publicly Verifiable Secret Sharing (PVSS). Results are in the form of collections of algorithm in pseudocode, that can be easily implemented. Finally, we discuss trade-offs between secret security and extended capabilities.