Abstract: Access control systems and methods are described, including receiving a request from a user to access a first object, where first access-control information is associated with the first object; determining that the first object is referenced by a second object; determining second access-control information associated with the second object, where the second access-control information identifies the user as having access to the second object; and providing to the user access to the first object based on to the second access-control information.

Abstract: A system and method for providing private demand-driven pricing for fixed cost digital goods are described. An encrypted price of identically-priced digital goods is additively perturbed. The digital goods are stored in a database by a seller system and an approximate revenue maximizing price for the digital goods has not been realized. A purchasing decision about one of the digital goods based upon the additively-perturbed price is sent to the seller system without revealing the particular digital good. A conditionally disclosed symmetric key is received in return under which the digital goods in the database have been encrypted. The purchaser system and seller system engage in symmetric private information retrieval on the database. The purchaser system decrypts the digital good purchased with the symmetric key. The seller system privately updates the encrypted price of the digital goods to close on the approximate revenue maximizing price whenever a purchase is made.

Abstract: A system and method for providing private demand-driven pricing for fixed cost digital goods are described. Symmetric private information retrieval is engaged on a table that includes public key encryptions of prices for digital goods stored in a database by a seller system, wherein a desired marginal pricing level has not been realized. The price of one digital good is decrypted with a private key for pricing by a purchaser system. A purchasing decision based upon the decrypted price is sent to the seller system without revealing the particular digital good being purchased. A conditionally disclosed symmetric key for goods is received under which the digital goods in the database have been encrypted. Symmetric private information retrieval is engaged on the database and the digital good purchased with the symmetric key is decrypted. The encrypted prices of the digital goods are privately updated based upon the desired marginal pricing level.

Abstract: A system and method for providing private demand-driven pricing for fixed cost digital goods are described. An encrypted price of identically-priced digital goods is additively perturbed. The digital goods are stored in a database by a seller system and an approximate revenue maximizing price for the digital goods has not been realized. A purchasing decision about one of the digital goods based upon the additively-perturbed price is sent to the seller system without revealing the particular digital good. A conditionally disclosed symmetric key is received in return under which the digital goods in the database have been encrypted. The purchaser system and seller system engage in symmetric private information retrieval on the database. The purchaser system decrypts the digital good purchased with the symmetric key. The seller system privately updates the encrypted price of the digital goods to close on the approximate revenue maximizing price whenever a purchase is made.

Abstract: A system and method for providing private demand-driven pricing for fixed cost digital goods are described. Symmetric private information retrieval is engaged on a table that includes public key encryptions of prices for digital goods stored in a database by a seller system, wherein a desired marginal pricing level has not been realized. The price of one digital good is decrypted with a private key for pricing by a purchaser system. A purchasing decision based upon the decrypted price is sent to the seller system without revealing the particular digital good being purchased. A conditionally disclosed symmetric key for goods is received under which the digital goods in the database have been encrypted. Symmetric private information retrieval is engaged on the database and the digital good purchased with the symmetric key is decrypted. The encrypted prices of the digital goods are privately updated based upon the desired marginal pricing level.