Encryption and decryption method, and PLC system using the same

Abstract

The invention relates to the field of industrial computer software safety, in particular to a method for encrypting and decrypting information in a memorizer and a PLC system for applying the method. The encrypting method of the invention comprises the following steps of storing an algorithm F()in the system; mapping the unique identifier of the memorizer into a cipher key K; encrypting the information stored in the memorizer by utilizing the cipher key K based on a symmetric encryption algorithm; and predefining the access strategy based on the user identity in order to control the user's access to the information stored in the memorizer; and storing the access strategy in the memorizer by utilizing the cipher key K based on the symmetric encryption algorithm. During the decryption process, decrypting, information stored in the memorizer is decrypted by utilizing the cipher key K based on the symmetric encryption algorithm, and the access strategy is decrypted by utilizing the cipher key K based on the symmetric encryption algorithm. Then the user's access to the information stored in the memorizer is controlled based on the user identity. The method and the system of the invention have the advantage of being capable of enhancing the safety of software codes.

Description

technical field [0001] The invention relates to the field of software security, specifically a method for encrypting and decrypting information in a memory, and a PLC system applying the method. Background technique [0002] Programmable logic controllers (PLCs) or programmable controllers are widely used in factory automation, for example to control an assembly line in a factory. Existing PLCs generally use program / control parameters for operation and control, for example, ladder logic, state transition diagrams, etc. (program codes in industrial control). However, the existing PLC does not provide a good access control mechanism, such as encrypting the software to prevent the control program from leaking, especially some existing control programs are stored in hot-swappable storage media, such as multimedia cards (MMC card), secure digital memory card (SD card), etc., so the control program is easy to leak, and the manufacturer that produces the control program may suffer...

AI Technical Summary

Problems solved by technology

[0008] For the field of industrial automation, programmable logic controllers (PLCs) or programmable controllers are somewhat different from existing computers. The reason is that most of the controllers used in the industrial field have limited processing capabilities and cannot That is a very complicated calculation, so most of the data processing methods applied to the computer cannot be run in the industrial control; another point is that the system design structure of the industrial controller is also different from that of the computer. For example, some memories in the industrial controller are What is not allowed to be accessed by users can only be accessed by the operating system of the industrial controller, so many data processing methods currently applied to computers are not suitable for running on industrial controllers

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