ENCRYPTION SYSTEM, ENCRYPTION METHOD, AND ENCRYPTION PROGRAM

• Main Authors: YAMAMOTO DAN, KITO DAISUKE, KITAHARA KEI, YASHIRO SATOSHI, SASAKI KOHEI
• Format: Patent
• Language: English; Japanese
• Published: 14.09.2017
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

PROBLEM TO BE SOLVED: To provide an encryption system for enabling re-encryption and re-signature.SOLUTION: A first information processing system 50 generates first and second keys, generates a first electronic signature being an electronic signature of the first key with a signature generation key for generating an electronic signature, generates a second electronic signature being an electronic signature of data of an encryption object with the second key, and encrypts the data of an encryption object and the second electronic signature with an encryption key generated by a second information processing system to generate encryption data. The second information processing system 60 receives the first key, the first electronic signature and the encryption data, verifies the validity of the first electronic signature with a signature verification key corresponding to the signature generation key and the first key, decrypts the encryption data into data of an encryption object and the second electronic signature with a description key corresponding to the encryption key, verifies the validity of the decrypted second electronic signature with decrypted data of an encryption object and the first key, and outputs the decrypted data of an encryption object when it is verified to be valid.SELECTED DRAWING: Figure 1 【課題】再暗号化及び再署名の可能な暗号化システムを提供する。【解決手段】第１情報処理システム５０は第１、２の鍵を生成し、電子署名を生成するための署名生成鍵で、第１の鍵の電子署名である第１電子署名を生成し、第２の鍵で、暗号化対象のデータの電子署名である第２電子署名を生成し、暗号化対象のデータ及び第２電子署名を、第２情報処理システムが生成した暗号化鍵で暗号化して暗号化データを生成する。第２情報処理システム６０は、第１の鍵、第１電子署名及び暗号化データを受信し、第１電子署名の正当性を、署名生成鍵に対応する署名検証鍵と第１の鍵で検証し、暗号化データを、暗号化鍵に対応する復号鍵で、暗号化対象のデータ及び第２電子署名に復号し、復号した第２電子署名の正当性を、復号した暗号化対象のデータ及び第１の鍵で検証し、正当と検証された場合に、復号した暗号化対象のデータを出力する。【選択図】図１