Encryption

Encryption is a way of scrambling information so only the person holding the right key can read it. Picture a locked box that anyone can carry, copy or steal, while the writing inside stays useless to them. Opening it needs the key, and that key is a long secret number your device keeps for you. So the maths behind it is not something you ever have to understand.

Two different moments need that box, and people mix them up. The first is information on the move, like an order leaving a customer's phone, an email going out, or a photo uploaded to your site. The second is information sitting still, such as files on a laptop, a backup on a disk, or customer names resting in a database. Protecting one does nothing for the other, yet most businesses only ever do the first.

The travelling half is usually handled for you, because that padlock in the address bar scrambles the line between the visitor and the server. So nobody on the café wi-fi can read what passes along it. The sitting-still half is the one that gets forgotten. A shop can have a perfect padlock on its website and still keep a plain copy of every customer address on an old laptop in the back room. When that laptop walks out of the door, the padlock counted for nothing. That is why Linkysoft asks where the copies live before it asks anything else about security work.

Now the uncomfortable part, which is that encryption does not save you from a stolen password. If a thief signs in with your name and your password, the system politely opens everything for him. It believes he is you, so the lock worked exactly as it was built to work. That is why a second step at sign-in, a code sent to your phone, is worth more than any improvement to the maths. It is also why four members of staff should never share one login.

So ask any supplier two plain questions. Where are the keys kept, and who on the team can read customer data without asking anyone first? A good answer names very few people. When Linkysoft builds a web application, card numbers and identity documents are stored scrambled and apart from the rest. That way a single mistake never exposes everything at once. It costs a little more at the start and far less the day something goes wrong.