Privacy Preserving Statistical Analysis for Distributed Databases

• US 20140137260A1
• Filed: 11/14/2012
• Published: 05/15/2014
• Est. Priority Date: 11/14/2012
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Rane, Shantanu, Wang, Ye, Lin, Bing-Rong
• Granted Patent: US 8,893,292 B2
• Time in Patent Office: Days
• US Class Current: 726/26
• CPC Class Codes: G06F 21/60 Protecting data
• CPC Class Codes: G06F 21/6245 Protecting personal data, e.g. for financial or medical purposes
• CPC Class Codes: G06F 21/6254 by anonymising data, e.g. decorrelating personal data from the owner's identification

Abstract

Aggregate statistics are determined by first randomizing independently data X and Y to obtain randomized data {circumflex over (X)} and Ŷ. The first randomizing preserves the privacy of the data X and Y. Then, the randomized data {circumflex over (X)} and Ŷ is randomized secondly to obtain randomized data {tilde over (X)} and {tilde over (Y)} for a server, and helper information T_{{tilde over (X)}|{circumflex over (X)}} and T_Ŷ|Ŷ for a client, wherein T represents an empirical distribution, and wherein the randomizing secondly preserves the privacy of the aggregate statistics of the data X and Y. The server then determines T_{{tilde over (X)},{tilde over (Y)}}. Last, the client applies the side information T_{{tilde over (X)}|{circumflex over (X)}} and T_Ŷ|Ŷ to T_{{tilde over (X)},{tilde over (Y)}} to obtain an estimated {dot over (T)}_X,Y, where “|” and “,” between X and Y represent a conditional and joint distribution, respectively.

Claims

1. A method for securely determining aggregate statistics on private data, comprising the steps of:

randomizing firstly and independently data X and Y to obtain randomized data {circumflex over (X)} and Ŷ

, respectively, wherein the randomizing firstly preserves a privacy of the data X and Y;

randomizing secondly independently the randomized data {circumflex over (X)} and Ŷ

to obtain randomized data {tilde over (X)} and {tilde over (Y)} for a server, and helper information T_{{tilde over (X)}|{circumflex over (X)}} and T_{{tilde over (Y)}|Ŷ}

[[T<sub>Ŷ

|Ŷ</sub>

]] for a client, respectively, wherein T represents an empirical distribution, and wherein the randomizing secondly preserves the privacy of the aggregate statistics of the data X and Y;

determining, at the server, T_{{tilde over (X)},{tilde over (Y)};}

applying, by the client, the helper information T_{{tilde over (X)}|{circumflex over (X)}} and T_{{tilde over (Y)}|Ŷ}

[[T<sub>Ŷ

|Ŷ</sub>

]] to T_{{tilde over (X)},{tilde over (Y)}} obtain an estimated {dot over (T)}_X,Y, wherein “

|” and

”

,”

between X and Y represent a conditional and joint distribution, respectively.

2. The method of claim 1, wherein the data X are produced by a first data source, and the data Y are produced by a second data source, and the data X and Y are produced independently in a distributed manner.

3. The method of claim 1, wherein the randomizing uses a Post RAndomisation Method (PRAM).

4. The method of claim 1, wherein the randomizing firstly and secondly are different.

5. The method of claim 1, wherein the helper information is small compared to the data X and Y.

6. The method of claim 1, wherein data X and Y are random sequences, and data pairs (X_i,Y_i) are independently and identically distributed.

7. The method of claim 1, wherein the randomizing preserves differential and distributional privacy of the data X and Y.

8. The method of claim 1, wherein the randomizing secondly provides distributional privacy that is stronger than the differential privacy provided by the randomizing firstly.