Information processing technique for pattern matching

An information processing system, comprising:

• a first information processing apparatus accessible to a first data storage unit that stores first text;
• and
• a second information processing apparatus, and
• wherein the first information processing apparatus comprises:
• a first generation unit that generates a first numerical vector by numerically vectorizing the first text stored in the first data storage unit;
• a second generation unit that generates a second numerical vector by squaring each component of the first numerical vector and a third numerical vector by cubing each component of the first numerical vector;
• a third generation unit that generates a first polynomial by executing a polynomial transformation of the first numerical vector, a second polynomial by executing the polynomial transformation of the second numerical vector, and a third polynomial by executing the polynomial transformation of the third numerical vector;
• an encryption unit that encrypts the first polynomial, the second polynomial and the third polynomial by a homomorphic encryption scheme capable of operating polynomials;
• and
• a first transmitter that transmits the first polynomial, the second polynomial, and the third polynomial to the second information processing apparatus,
• the second information processing apparatus comprises:
• a first receiver that receives the first polynomial, the second polynomial, and the third polynomial from the first information processing apparatus;
• an execution unit that executes a predetermined operation while keeping data used in the predetermined operation encrypted, by using a fourth polynomial obtained by the polynomial transformation and the homomorphic encryption of a fourth numerical vector, a fifth polynomial obtained by the polynomial transformation and the homomorphic encryption of a fifth numerical vector, and a sixth polynomial obtained by the polynomial transformation and the homomorphic encryption of a sixth numerical vector, wherein the fourth numerical vector is generated by numerically vectorizing second text, the fifth numerical vector is generated by squaring each component of the fourth numerical vector, the sixth numerical vector is generated by cubing each component of the fourth numerical vector, and the fourth polynomial, the fifth polynomial and the sixth polynomial are stored in a second data storage unit;
• and
• a second transmitter that transmits a result of the predetermined operation, and
• the first information processing apparatus comprises:
• a second receiver that receives the result of the predetermined operation.

A computer-readable, non-transitory storage medium storing a program for causing a computer to execute a process, the process comprising:

• receiving a first polynomial obtained by a polynomial transformation and homomorphic encryption of a first numerical vector, a second polynomial obtained by the polynomial transformation and the homomorphic encryption of a second numerical vector, and a third polynomial obtained by the polynomial transformation and the homomorphic encryption of a third numerical vector, wherein the first numerical vector is generated by numerically vectorizing first text, the second numerical vector is generated by squaring each component of the first numerical vector, the third numerical vector is generated by cubing each component of the first numerical vector;
• executing a predetermined operation while keeping data used in the predetermined operation encrypted, by using a fourth polynomial obtained by the polynomial transformation and the homomorphic encryption of a fourth numerical vector, a fifth polynomial obtained by the polynomial transformation and the homomorphic encryption of a fifth numerical vector, and a sixth polynomial obtained by the polynomial transformation and the homomorphic encryption of a sixth numerical vector, wherein the fourth numerical vector is generated by numerically vectorizing second text, the fifth numerical vector is generated by squaring each component of the fourth numerical vector, the sixth numerical vector is generated by cubing each component of the fourth numerical vector, and the fourth polynomial, the fifth polynomial and the sixth polynomial are stored in a data storage unit;
• and
• sending back a result of the predetermined operation.