Write the password (plaintext) together with the program file into PLC through programming software. When the PLC is connected with the programming software, it prompts for the password, and then the PLC returns the actual password. The comparison of passwords is realized in the programming software. The password written into PLC by this encryption method does not need any encryption calculation. Easier to crack!
Write password and program file into PLC through programming software. The password (ciphertext) written into PLC is encrypted in programming software (mostly simple encryption algorithm). When the programming software is connected to PLC, it prompts for the password, and then PLC returns the ciphertext password, so as to realize ciphertext comparison in the programming software. This encryption method is very difficult to crack! It is necessary to trace and analyze the programming program and find out the encryption algorithm.
The programming software writes the password plaintext together with the program file into PLC, which encrypts the password plaintext, calculates the ciphertext and stores it in PLC. When the PLC is connected with the programming software, it prompts for the password, and the PLC does not need to return the ciphertext, so the comparison of ciphertext is realized inside the PLC. This encryption method is not easy to realize and needs the support of PLC hardware and PLC operating system. This kind of encryption is the most difficult to crack.
Decryption mode of PLC:
Listen to the communication port directly and find out the plaintext password.
Monitor the communication port, track the programming software and find out the relationship between plaintext and ciphertext (algorithm).
There is no very effective method at present.
All kinds of cracking require certain skills, experience and related software, and real experts disdain this. The purpose of writing this article is not to teach you how to crack, but to remind PLC manufacturers to improve the confidentiality of passwords.
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