Order-preserving encryption system, device, method and program

摘要

This invention allows order-preserving encryption with a simpler algorithm while ensuring security. An order-preserving encryption system includes encryption means 1 for, upon receiving a plaintext as input, generating an order-preserved cipher in accordance with a predetermined probability distribution generated based on values determined from the plaintext and on a set generated from a plaintext space included in a secret key using a uniform distribution, or a key to a predetermined pseudorandom function, the probability distribution representing a conditional probability as a binomial distribution.