Patent ID: 9735959
Date: 2017-08-15
CPC Classifications: G06F,H04L

Claim:
1. A method for controlling access to data owned by a plurality of users, the data being stored at a cloud storage platform at which each of the plurality of users has a personal account to which files can be uploaded, the method comprising: a) evaluating access control policies exerted by the plurality of users on the data owned by the plurality of users; b) generating key shares of an encryption key and delegating, based on the access control policies, the key shares to one or more designated users, wherein the generating key shares and the delegating the key shares is performed according to a collusion resistant sharing scheme; c) producing encrypted data shares by applying an encryption scheme on all parts of the data owned by the plurality of users so as to securely disperse the data owned by the plurality of users, wherein according to the encryption scheme, decryption of encrypted data requires the encryption key and at least a predetermined number of the data shares; d) delegating each of the encrypted data shares to the one or more designated users; and e) distributing the data shares and the key shares to the one or more designated users.