Encryption processing apparatus, encryption method, decryption processing apparatus, decryption method and data structure

An encryption method implemented by an encryption processing apparatus, wherein the encryption processing apparatus implements steps of:

• cutting subject data in plain text by a predetermined number of bits into multiple pieces of plain text cut data;
• encrypting the multiple pieces of the plain text cut data with a predetermined key and a predetermined algorithm to render it as multiple pieces of encrypted cut data;
• generating condition data including data on at least one of a condition in the case of allowing decryption of each individual piece of the encrypted cut data and a condition in the case of prohibiting decryption of each individual piece of the encrypted cut data;
• encrypting the condition data with a predetermined key and a predetermined algorithm to render it as encrypted condition data;
• generating basic condition data including data on at least one of a condition in the case of allowing decryption of the encrypted condition data and a condition in the case of prohibiting decryption of the encrypted condition data;
• and
• connecting the multiple pieces of the encrypted cut data, the encrypted condition data and the basic condition data as one to render them as a series of encrypted data premised to be decrypted by a predetermined decryption processing apparatus, and wherein:
• in the step of connecting the multiple pieces of encrypted cut data, the encrypted condition data and the basic condition data as one to render them as a series of encrypted data premised to be decrypted by the predetermined decryption processing apparatus,
• the encryption processing apparatus connects the encrypted cut data, the encrypted condition data and the basic condition data as one to render them as a series of encrypted data in a manner the encrypted condition data is positioned ahead of the encrypted cut data having its decryption allowed or prohibited according to the condition included in the condition data which is a source of the encrypted condition data and also the basic condition data is positioned ahead of the encrypted condition data.

A data structure of encrypted data connecting the following as one to render them as a series and premised to be decrypted by a predetermined decryption processing apparatus:

• multiple pieces of encrypted cut data obtained by encrypting multiple pieces of plain text cut data obtained by cutting subject data in plain text by a predetermined number of bits with a predetermined key and a predetermined algorithm;
• encrypted condition data obtained by encrypting condition data including data on at least one of a condition in the case of allowing decryption of each individual piece of the encrypted cut data and a condition in the case of prohibiting decryption of each individual piece of the encrypted cut data with a predetermined key and a predetermined algorithm;
• and
• basic condition data including data on at least one of a condition in the case of allowing decryption of the encrypted condition data and a condition in the case of prohibiting decryption of the encrypted condition data, and wherein:
• as for the encrypted cut data, the encrypted condition data and the basic condition data, the encrypted condition data is positioned ahead of the encrypted cut data having its decryption allowed or prohibited according to the condition included in the condition data which is a source of the encrypted condition data and the basic condition data is positioned ahead of the encrypted condition data.