Patent ID: 11907380
Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G  H

Claim 9:
10. The computer-implemented method of claim 1, further comprising:
for computing a polynomial multiplication c1c2 of first cryptographic element c1 and a second cryptographic element c2, each having n polynomial coefficients, wherein said matrix of multibit values comprises a Discrete Fourier Transform matrix M1 with values ei,j, i=0 to (n−1), j=0 to (n−1), given by ei,j=ki×j modulo p, wherein kN=1 modulo p, N≥n and p is a predefined prime number for a homomorphic encryption system, comprising:
storing an Inverse Discrete Fourier Transform matrix M2 corresponding to M1 as a further matrix of multibit values in a further crossbar array of the multiply-accumulate unit;
supplying n coefficients of element c1 bitwise to respective word-lines connected to cells storing values in M1, and processing the digital signals obtained from successive bits of the coefficients to obtain a Discrete Fourier Transform T(c1) of the coefficients of element c1;
supplying n coefficients of element c2 bitwise to respective word-lines connected to cells storing values in M1, and processing the digital signals obtained from successive bits of the coefficients to obtain a Discrete Fourier Transform T(c2) of the coefficients of element c2;
performing component-wise multiplication of corresponding components of T(c1) and T(c2) to obtain another Discrete Fourier Transform T(c3) of the coefficients of a cryptographic element c3; and
supplying the components of T(c3) bitwise to respective word-lines connected to cells storing values in M2 to obtain analog accumulation signals on the bit-lines, converting the analog accumulation signals to digital signals and processing the digital signals obtained from successive bits of the components to obtain a result of the polynomial multiplication c3=c1c2.