Encryption apparatus, decryption apparatus, encryption method, decryption method, security method, program, and recording medium
US8515060B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 2010 |
| Grant date | Aug 20, 2013 |
| Priority date | — |
| Expiry date | Aug 15, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/0825
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Security against CCA is improved without providing space for just improving the security against CCA in a ciphertext space. In encryption processing, a first ciphertext C1 is calculated from a plaintext M and a symmetric key K; a value containing a value corresponding to the symmetric key K and a value corresponding to the first ciphertext C1 is put into a collision-resistant function H to calculate a function value of the function H; and r corresponding to the function value is used to calculate second ciphertext C2=r·(Σμ=1nvμ·bμ)+ρ·bn+1∈G1n+1. In decryption processing, the second ciphertext C2∈G1n+1 and key information D1*=α·(Σμ=1nwμ·bμ*)+bn+1*∈G2n+1 are put into a bilinear function e to calculate a function value S˜=e(C2, D1*)∈GT; a value corresponding to the function value S˜ and the first ciphertext C1 are put into the collision-resistant function H to calculate a function value of the function H; and it is judged whether r˜ corresponding to the function value satisfies C2=r˜·(Σμ=1nvμ·bμ)+ρ˜·bn+1∈G1n+1.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.