Think about the verification code. Is your verification code safe?

I have previously written a verification code number that identifies a single background and a single font size by comparing the verification code number region. After writing the code, I found that many websites only change the verification code when they get the verification code image. In this way, if we only access the image once, and then submit it with this number each time, you can always crack the user name and password of the website.
The most important thing is that mobile companies have such problems. However, it limits the number of password retries.
Here, I hope you can take it as a warning.

As for "not to let the computer see, it is to let people see", there is no other meaning, just hope that people can understand. The mandatory verification code is used for computer recognition.