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ENCRYPTION CONTROL SYSTEM, ENCRYPTION CONTROL METHOD, AND ENCRYPTION CONTROL PROGRAM NEW

外国特許コード F200010254
整理番号 (S2019-0270-N0)
掲載日 2020年11月5日
出願国 世界知的所有権機関(WIPO)
国際出願番号 2020JP008362
国際公開番号 WO2020179672
国際出願日 令和2年2月28日(2020.2.28)
国際公開日 令和2年9月10日(2020.9.10)
優先権データ
  • 特願2019-039026 (2019.3.4) JP
発明の名称 (英語) ENCRYPTION CONTROL SYSTEM, ENCRYPTION CONTROL METHOD, AND ENCRYPTION CONTROL PROGRAM NEW
発明の概要(英語) Disclosed is an encryption control system for making it possible to prevent all keys from being deciphered within the service life of a controlling system even if the key length of cryptographic keys used for encryption control is relatively short, the encryption control system controlling a control target by an encryption controller capable of concealing information in the controlling system by cryptography. The encryption control system comprises: a cryptographic key updating unit that dynamically updates a private key and a public key in every encryption step; and a ciphertext updating unit that dynamically updates a ciphertext in every encryption step. The cryptographic key updating unit and the ciphertext updating unit each include a random number generator, and are configured so that the same random number is generated when updating the cryptographic keys and the ciphertext.
従来技術、競合技術の概要(英語) BACKGROUND ART
In recent years, with the development of information technology such as the Internet, control systems using information technology have been becoming networked in important infrastructure such as electric power and water supply and large-scale control systems such as chemical plants. In such a networked control system (control system), various devices in the system are interconnected via a network.
In such a control system, various devices are interconnected, so that the processing speed of the entire system can be improved and the processing contents can be enhanced. Further, since the manager of the system can monitor and control the plant from a remote place through the network, many benefits can be obtained in terms of system management.
However, networking in the control system improves convenience and may damage the system and its surroundings. In fact, cyber attacks on control systems for monitoring or controlling plant operations such as power plants and factories appear, and there is concern as social important problems. For example, in Australia in 2000 years, a networked sewage treatment facility attacks and 100 million liters of sewage overflow the city. In addition, in 2010 years, the nuclear facilities of Iran are infected with Stuxnet virus, and the facilities are destroyed.
As described above, damage due to cyber attack tends to become serious, and technology development for protecting networked control systems from cyber attack is urgent. Therefore, in the field of control engineering, research for diverting information system security technology and detection of cyber attack have been carried out. For example, in network communication between the controller (controller) and the controlled (plant), research for preventing eavesdropping or tampering of a signal by encrypting the signal has been carried out.
The inventors have already developed an encryption control system technology which eliminates the need for a private key on the controller side by directly performing arithmetic processing on encrypted input data and output data by a controller corresponding to the core portion of the control system without decrypting the encrypted input data and output data once, and obtaining a patent). In the technology described in Patent Document 1, the secret key may be provided only on the plant side, and the secret key need not be moved to the controller or the plant. thus, the risk of loss or leakage of the secret key can be reduced.
Non-Patent Document 1) proposes a method of determining a control input while keeping signals and parameters inside the controller (Controller) secret by encryption. Furthermore, The inventors conducted experiments on encryption control using a key of 128 (bit) or less by ElGamal encryption, and verified real-time properties of (Non-Patent Document 2). In this Non-Patent Document 2, the inventors have reported that there is a trade-off relationship between security and processing time since the processing time increases as the encryption key used in the encryption control system becomes longer. The processing time is a time required for "encryption and decryption" processing, and it is known that when the encryption key is lengthened, not only decryption but also encryption processing time is increased.
The real-time property will now be described. The real-time property refers to a temporal constraint on the processing time from the start of 1 processes to the end of the system. For example, if a certain control system is designed to perform encryption control 1 times per 10 (ms), the processing time must always be within 10 (ms). In the verification method, encryption control is actually repeatedly executed by 1 million times and 10 million times by using an experimental device to measure the processing time. When the processing time does not exceed the temporal restriction of 10 (ms) during the control, the control system guarantees the real-time performance at the sampling period of 10 (ms).
Generally, when the privacy such as the account number of an individual is managed, the privacy such as the account number of the individual must be kept secret at least over the life of the individual. Therefore, it is necessary to make it impossible to decrypt the cipher for an extremely long period of time such as during the life of an individual, and in order to achieve this, it is necessary to prepare a strong cipher system which is practically difficult to decrypt the cipher.
On the other hand, in many control systems, the service life of about ~ 20 years has been set. That is, as long as cyber attack can be prevented within the service life, there are many cases where there are no problems even if the secret key and the input/output signal are exposed after the service life of the control object exceeds the service life. Therefore, in key length design problems used in existing encryption control systems, secrecy which is difficult to decrypt is important. in encryption control systems for preventing cyber attacks within the service life, a new key length design index which combines secrecy and availability of the control systems is required.
  • 出願人(英語)
  • ※2012年7月以前掲載分については米国以外のすべての指定国
  • THE UNIVERSITY OF ELECTRO-COMMUNICATIONS
  • 発明者(英語)
  • KOGISO Kiminao
  • KUSAKA Masahiro
国際特許分類(IPC)
指定国 National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DJ DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS JO JP KE KG KH KN KP KR KW KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN WS ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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