Cryptographic System, Updating Method, and Non-Transitory Storage Medium Encoded with Computer Readable Program

A method for updating a key, comprising:

• encrypting original data in a first encryption method using a first key to generate first encrypted data;
• encrypting the first encrypted data in a second encryption method using a second key to generate second encrypted data;
• storing the second encrypted data generated;
• in response to an instruction received to update a current version of the first key and a current version of the second key, updating the current version of the first key to a new version of the first key and also updating the current version of the second key to a new version of the second key;
• and
• when updating the current version of the second key, converting the second encrypted data encrypted with the current version of the second key into a state encrypted with the new version of the second key.

A non-transitory storage medium encoded with a computer readable program causing a computer to:

• encrypt original data in a first encryption method using a first key to generate first encrypted data;
• encrypt the first encrypted data in a second encryption method using a second key to generate second encrypted data;
• store the second encrypted data generated;
• in response to an instruction received to update a current version of the first key and a current version of the second key, update the current version of the first key to a new version of the first key and also update the current version of the second key to a new version of the second key;
• and
• when updating the current version of the second key, convert the second encrypted data encrypted with the current version of the second key into a state encrypted with the new version of the second key.