| 摘要 |
PROBLEM TO BE SOLVED: To provide a common key homomorphic encryption with enhanced calculation efficiency by increasing the concurrency.SOLUTION: The common key encryption device includes a storage, a plaintext reception section, a plaintext polynomial generation section, a mask polynomial generation section, and an encryption section. The storage stores a common key which is constituted of plural elements of a first polynomial ring. The plaintext reception section receives an input of a piece of plaintext information. The plaintext polynomial generation section generates a plaintext polynomial by embedding the plaintext information of the received input in at least one term of a polynomial in a partial space of the first polynomial ring. The mask polynomial generation section generates a mask polynomial which includes the common key in a solution on the basis of a second commutative ring which is defined in the first polynomial ring. The encryption section generates a ciphertext by using the plaintext polynomial and the mask polynomial. |
