Generate text verification code on server side using PHP

The realization principle of text verification code:

1): Prepare some pictures to store them in the database, each image corresponding to an identity field.

2): Combine the picture with the Identity field in the form of an array on the server side.

3): Randomly returns the picture to the client and accepts the field entered by the user.

4): Compare the fields entered by the user with the information stored by the server with each picture.

5): The same is passed, otherwise does not pass.

Generate text verification code on server side using PHP