In a data registration phase, encrypted data is calculated by encrypting input data to be concealed by using a secret key, registration data is generated based on the encrypted data and a verification key, and the registration data is stored as a registration template in a storage unit together with an identifier for uniquely identifying the registration data. In an encrypted text verification phase, a data verifying request is generated in which input data to be verified has been encrypted by using a random number, the registration template stored in the storage unit and the data verifying request are verified to produce a determined result, a verified result including a part or all of the registration template corresponding to the determined result is produced, and data is restored based on the verified result to produce a restored result.