What is this “Verified”?

The short answer

Your browser has solved a small computing task for us. It replaces the usual picture puzzles – you do not have to click on traffic lights or type out distorted letters. The method is called ALTCHA, it is open source and it runs on our own server. No other company is involved.

Why check at all?

Forms on the internet are submitted by programs, not only by people. Without protection we receive advertising, fraud attempts and automated bulk enquiries every day – and your genuine message gets lost among them or ends up in the spam folder.

The common answer to this are captchas from the large providers. Their price is high: they recognise you across websites, evaluate your behaviour and pass data to companies outside Europe. We did not want to put you through that.

ALTCHA turns the idea around: instead of testing you, we let your device do a little work. For a person filling in a form that is imperceptible. For a machine trying to submit thousands of times, the computing time adds up until the effort no longer pays off.

How it works, step by step

1. 1

   You open a page with a form

   Your browser loads a small program from our server and is given a computing task. The task is different for every visit and valid for a few minutes only.

2. 2

   Your device does the work

   The task boils down to: “Find a number that, together with this text, produces a result with certain properties.” It can only be solved by trying – your device simply counts up until it fits. That takes a fraction of a second and runs in the background.

3. 3

   The tick appears

   Once the task is solved, the box reads “Verified”. There is nothing to click, nothing to type out and no traffic lights to find in pictures.

4. 4

   We check the result

   The solution is sent along when you submit. Our server takes a fraction of a second to recalculate whether it matches the task set – and whether the same solution has not already been submitted before.

The technical term for this is proof of work. The same idea was originally devised against spam email: anyone wanting to send a great many messages should have to spend noticeable computing time on it.

What expressly does not happen

• No cookies are set.
• Nothing is stored on your device and nothing is read from it – neither your browsing history nor installed fonts, screen size or anything similar.
• Your behaviour is not observed – no mouse movements, no typing speed, no profile.
• No outside company receives any data. The service runs on our own server in Germany.
• Nothing is kept beyond the individual request.

Because your terminal equipment is neither accessed nor written to, no consent is needed for this – and you need no further consent dialogue.

What we actually see

Retrieving the program and the computing task creates the usual access logs on our server: IP address, time, address requested and browser identification. Added to that is the result of the calculation itself – a sequence of numbers with no reference to you as a person. Nothing else.

Further reading

• The section “Spam protection (ALTCHA)” in our privacy policy – the legal wording, with legal basis and retention period.
• ALTCHA on GitHub – the complete source code of the method. Anyone can read what the program does in your browser; we have not changed anything about it.
• Any questions? Do write to us – and you can do so without any tick, by email to info@techeve.de.