US 12,461,917 B2
Secure equi-join apparatus, secure equi-join method, and program
Junko Hashimoto, Tokyo (JP); and Dai Ikarashi, Tokyo (JP)
Assigned to NTT, Inc., Tokyo (JP)
Appl. No. 18/572,808
Filed by NTT, Inc., Tokyo (JP)
PCT Filed Jul. 2, 2021, PCT No. PCT/JP2021/025131
§ 371(c)(1), (2) Date Dec. 21, 2023,
PCT Pub. No. WO2023/276142, PCT Pub. Date Jan. 5, 2023.
Prior Publication US 2024/0289335 A1, Aug. 29, 2024
Int. Cl. G06F 16/2455 (2019.01); G06F 21/60 (2013.01); G06F 21/62 (2013.01)
CPC G06F 16/2456 (2019.01) [G06F 21/602 (2013.01); G06F 21/6227 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A secret equi-join device comprising:
(a) a storage;
(b) a first subkey column addition processing circuitry;
(c) a second subkey column addition processing circuitry; and
(d) a secret equi-join processing circuitry, wherein
(a) the storage stores
a first concealed table that is concealed information of a first table including a first key column having a plurality of first keys and a first arbitrary element column having a plurality of first arbitrary elements, and
a second concealed table that is concealed information of a second table including a second key column having a plurality of second keys and a second arbitrary element column having a plurality of second arbitrary elements,
(b) the first subkey column addition processing circuitry obtains, by secure computation using the first concealed table, a first concealed additional table that is concealed information of a first additional table which is obtained by adding a first subkey column to the first table,
the first subkey column has a plurality of first subkeys,
each of the first keys is associated with any of the first subkeys,
a maximum value of a number of the first keys of same value contained in the first key column is KL,
KL is an integer of 2 or more,
the first keys of the same value are associated with the first subkeys of different values,
(c) the second subkey column addition processing circuitry obtains, by secure computation using the second concealed table, a second concealed additional table that is concealed information of a second additional table which is obtained by adding a second subkey column to a third table,
respective records in the second table include the respective second keys and the respective second arbitrary elements,
the third table is a table which is obtained by adding a plurality of copied records, obtained by copying each of the records in the second table K times, to the second table, and K≥KL,
the third table includes a third key column having a plurality of third keys that include the second key and a copy of the second key, and a third arbitrary element column having a plurality of third arbitrary elements that include the second arbitrary element and a copy of the second arbitrary element,
the second subkey column contains a plurality of second subkeys,
each of the third keys is associated with any of the second subkeys,
when the third key column contains the third keys representing a same common value as any of the first keys, at least some of the third keys representing the common value are associated with the second subkeys of same value as the first subkeys associated with the first keys representing the common value, and
(d) the secret equi-join processing circuitry obtains, by secure computation using the first concealed additional table and the second concealed additional table, a concealed joined table that is concealed information of a joined table which is obtained by equi-joining the first additional table and the second additional table, using a pair of the first key and the first subkey as a key attribute of the first additional table and a pair of the third key and the second subkey as a key attribute of the second additional table.