Electronic Content Distribution Based On Secret Sharing

A method for processing information, comprising:

• receiving at a first client an item of encrypted information distributed to a plurality of clients;
• receiving at the first client a given key-share from among multiple, respective key shares distributed to the clients, such that each client requires a key-share that has been distributed to at least one other client in order to reconstruct a key for decrypting the encrypted information;
• receiving at the first client a request from a second client to convey the first key-share from the first client to the second client;
• and
• responsively to the request, conveying the given key-share from the first client to the second client and reporting to a server that the given key-share has been conveyed to the second client.

A system for distributing information, comprising:

• a plurality of clients, configured to communication over a communication network, including at least first and second clients;
• and
• a server, which is configured to distribute an item of encrypted information over the communication network to the clients and to distribute respective key-shares to the clients, including at least first and second key-shares distributed to the first and second clients, such that each client will require a key-share that has been distributed to at least one other client in order to reconstruct a key for decrypting the encrypted information,
• wherein at least the first client is configured, upon receiving a request from a second client to convey the given key-share from the first client to the second client, to convey the given key-share to the second client and report to the server that the given key-share has been conveyed to the second client.