OBLIVIOUS TRANSFER WITH ACCESS CONTROL

• US 20110145589A1
• Filed: 10/21/2010
• Published: 06/16/2011
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dubovitskaya, Maria, Camenisch, Jan Leonhard, Neven, Gregory
• Granted Patent: US 8,522,040 B2
• Time in Patent Office: Days
• US Class Current: 713/185
• CPC Class Codes: G06F 21/6227 where protection concerns the structure of data, e.g. records, types, queries
• CPC Class Codes: G06F 21/6254 by anonymising data, e.g. decorrelating personal data from the owner's identification
• CPC Class Codes: G06F 21/6263 during internet communication, e.g. revealing personal data from cookies
• CPC Class Codes: G06F 2221/2107 File encryption
• CPC Class Codes: H04L 2209/42 Anonymization, e.g. involving pseudonyms
• CPC Class Codes: H04L 2209/50 Oblivious transfer
• CPC Class Codes: H04L 9/3221 interactive zero-knowledge proofs

Abstract

A protocol for anonymous access to a database where the different records have different access control permissions is described. The permissions can be attributes, roles or rights that an authorized user needs to have to access the record. The database provider does not learn which record the user accesses and which attributes or roles the user has when she accesses the database. The database provider publishes the encrypted database where each record is encrypted with a key that is derived from at least the index of the record, its access control attributes and a secret key of the database provider. The user obtains a credential from an issuer for each access control attribute (ACL) that is associated with the user. Then the user retrieves the key for a particular record from the database provider and uses this key to decrypt the encrypted record.

Claims

1. A computer system comprising:

a database server (DB) comprising publishing means to publish an encrypted form (ω

_DB) of a database (DBase), the database (DBase) comprising at least one record with an associated index and a list of access-control attributes for each record;

at least one user (U_1, U_2, . . . , U_M) of the database (DBase); and

an Issuer (I) comprising means to provide a credential for each access-control attribute of the database (DBase), which is assigned to the at least one user (U_1, U_2, . . . , U_M);

wherein

the publishing means being responsive to database encryption means, the database encryption means comprising;

key generation means to generate an encryption key for a record such that the encryption key is derived from at least the index of the record and the access-control attributes and a secret key of the database server (DB); and

record encryption means responsive to the key generation means to encrypt a database record with the encryption key.

2. The computer system of claim 1, where the database encryption means further comprise:

key provision means responsive to the record encryption means to provide the encryption key to the user (U_1, U_2, . . . , U_M), the key provision means comprising means to perform a proof with the user (U_1, U_2, . . . , U_M) regarding the possession of a credential for all the access-control attributes of a particular record.

3. A method for anonymously reading records from a database (DBase) provided by a database server (DB), wherein the database (DBase) comprises at least one record with an associated index and a list of access-control attributes for each record, and wherein the database provider (DB) publishes an encrypted form (ω

_DB) of the database (DBase), and wherein at least one user (U_1, U_2, . . . , U_M) of the database (DBase) obtains credentials from an Issuer (I) for each access-control attribute which is assigned to the at least one user (U_1, U_2, . . . , U_M),

wherein

for each record in the encrypted form (ω

_DB) of the database (DBase) performing;

generating (620) a key that is derived from at least the index of the record and the access-control attributes and a secret key of the database server (DB); and

encrypting (620) the record with the key.

4. The method of claim 3, further comprising:

providing the encryption key to the at least one user (U_1, U_2, . . . , U_M); and

performing a proof with the at least one user (U_1, U_2, . . . , U_M) regarding the possession of a credential for all the access-control attributes of a particular record.

5. The method of claim 3 further comprising a computer program (1512) loadable into the internal memory (1506) of a digital computer system (1500) and having a plurality of software code portions.