Patent ID: 11909873
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Digital communication (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 7:
8. A decryption method comprising:
acquiring a ciphertext in which one of a predicate vector of arithmetic branching programs (ABP) and an attribute vector is set over a basis B, wherein the basis B and a basis B* are dual bases in dual vector spaces, which are generated based on a length (n′) of a public attribute vector and a length (n) of a secret attribute vector such that each of the basis B and the basis B* consists of L partial bases, wherein L is an integer equal to n′+n, each of n′ and n is an integer greater than or equal to 1, and the public attribute vector is published;
acquiring a decryption key in which the other one of the predicate vector and the attribute vector is set over the basis B*; and
decrypting the ciphertext by performing a pairing operation on the acquired ciphertext and the acquired decryption key.