We should often hear the light module encryption or write code, especially some big factory network equipment, are required to use their original module. So, what exactly is write code encryption? How do the third-party module manufacturers deal with the device manufacturers‘ code encryption? Can you crack it? What happens if you can‘t crack it?

First of all, strictly speaking, we usually talk about compatibility problems, and write code encryption is not the same thing, compatibility problems refer to the above mentioned problems, because the implementation of the standard is different, resulting in a mismatch when working together, is not intentional. But write the code and encrypt the module so that it doesn‘t work on the device, that‘s intentional.

Based on the definition of light module of industry standards, light module has 2 for each 128 - byte write code line, the two written inside the six-yard box storage vendor, model, serial number, as well as DDM information (allowing the voltage, current, temperature, range of light power, and actual collected these values) and compatible code, etc. Many devices, in switches and other network equipment, and do the limit, optical module in them, will be through the I2C bus to read light switch module six-yard box inside information, through these information, the device can determine whether the module is their original module, if it is found that is not the original factory, can take some action. Here different manufacturers have different practices, mainly have so a few kinds.

1. No compatibility control is done, that is, the device does not read the compatibility code inside the module to make judgment, and any module can be plugged into it.

2. Check the compatibility code in the module to determine whether it is compatible or not. However, since the compatibility code is plaintext, any third-party module manufacturers can easily obtain this compatibility code, so that when these third-party module manufacturers leave the factory, they can be compatible as long as they write the compatibility code of the compatible manufacturer in their modules. So this is the same thing as leaving things unguarded. Many network card manufacturers part or all of their products, are this practice.

3. The inside of the module is compatible with code is dynamic compatible code, some information is based on the inside of the module, such as serial Numbers, and even some unique ID chip inside, and then through specific algorithm, written in after calculation, in this case, the third party to solve the difficulty is bigger, but as long as you can know all the algorithms and participate in the field and the location of algorithm, it is possible. Some big factory part of the product, it is this kind of practice.

For vendors checking for compatibility in 2 and 3 above, if they find incompatibilities, there will be a number of different measures, some will not UP directly, some will alert and/or keep you from seeing the DDM information. Current manufacturer uses latter commonly, belong to more moderate practice. This is not a technical problem, but a marketing strategy problem.