A non-transitory machine-readable storage medium comprising a computer program, which, when executed, causes a device to perform a data generation method for CAPTCHA (Completely Automated Public Test to tell Computers and Humans Apart) data, comprising:
- a first program code for determining a first data set according to at least one first data corresponding to an operation, wherein the first data represents sensitive data corresponding to the operation;
- a second program code for generating a group of CAPTCHA data corresponding to the first data set according to the first data;
- and
- a third program code for hiding corresponding encrypted data into each CAPTCHA data in the group of CAPTCHA data, wherein the encrypted data includes information corresponding to the operation.