exactly what recaptcha does, for example. Knowing that you have to type a word because a computer failed to identify which word is it makes creating a program that does that no easier. Same with the image ones. While criptography is a different problem, the argument is the same: you want something that can be verified to be hard to break otherwise someone will eventually figure it out
BOB_DROP_TABLES
joined 1 year ago
They do exist. Mine has a mute button. The keypad is awful though. I don't remember the brand and not at home, but can look it up later
The text is not generated. It's from photos of books that failed ocr. The photos are then distorted to make it even harder in order to become that captcha. 2 words are used 1 is a control (to know if the response is correct), the other is one they what to know what says (to add to the pool of words and finish digitizing the book).