US 12,341,885 B2
Secret batch approximation system, secure computation device, secret batch approximation method, and program
Koki Hamada, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/055,993
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed May 20, 2019, PCT No. PCT/JP2019/019846
§ 371(c)(1), (2) Date Nov. 17, 2020,
PCT Pub. No. WO2019/225531, PCT Pub. Date Nov. 28, 2019.
Claims priority of application No. 2018-100340 (JP), filed on May 25, 2018.
Prior Publication US 2021/0287573 A1, Sep. 16, 2021
Int. Cl. H04L 9/08 (2006.01)
CPC H04L 9/0894 (2013.01) [H04L 2209/46 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A secret batch approximation system including three or more secure computation apparatuses for calculating a concealed text [z] :=([z1], . . . , [zn]) of an approximate value z :=(z1, . . . , zn) for a function value y :=(y1, . . . , yn) satisfying yj=f(xj) for each integer j, the integer j being greater than or equal to 1 and less than or equal to n, the three or more secure computation apparatuses cooperatively calculating the concealed text [z] using a concealed text [x] :=([x1], . . . , [xn]) of n pieces of values x :=(x1, . . . , xn) as input when n is defined as an integer greater than or equal to 1, wherein
m is defined as an integer greater than or equal to 2, g is defined as a polynomial for approximating each section of m sections into which a function f is divided, i is defined as each integer and is greater than or equal to 1 and less than or equal to m, Ri is defined as one of the m sections, and pi is defined as a parameter of the polynomial g corresponding to the section Ri,
each of the three or more secure computation apparatuses comprises processing circuitry configured to:
receive the concealed text [x] :=([x1], . . . , [xn]) as input;
acquire a concealed text [a] :=([a1], . . . , [an]) of a parameter a :=(a1, . . . , an) corresponding to a value x :=(x1, . . . , xn) for each integer j, where aj is defined as a parameter pi corresponding to the section Ri including the value xj;
calculate the polynomial g([x], [a]) by using the concealed text [x] of the value x as input based on the concealed text [a] of the parameter a so as to obtain the concealed text [z] of the approximate value z for the function value y; and
set the concealed text [z] as output of each of the three or more secure computation apparatuses,
wherein
the processing circuitry acquires the concealed text [a] :=([a1], . . . m [an]) of the parameter a :=(a1, . . . , an) based on a formula:
([a1], . . . ,[an])←BatchMap([x],(u1, . . . ,um),(p1, . . . ,pm))
where BatchMap is defined as a secure computation batch mapping algorithm, ui is defined as a value indicating a boundary of the section Ri, and ui<u+1.