I used to think that when I formatted a USB drive or deleted a file, the data was physically wiped off the disk. I imagined a tiny magnet or a laser clearing the surface until it was blank again.
But then I learned that computers are lazy. When you delete something, the data is usually still there—the computer just pretends it isn't.
Let's look at why "deleting" is just a lie we tell ourselves.
I see this all the time in configuration files or old code: a password or an API key that looks like a bunch of gibberish, like SGVsbG8gV29ybGQ=.
"Oh, it's encrypted," someone might say.
But it’s not! It’s just Base64 encoded. Anyone with a terminal or a web browser can turn that gibberish back into plain text in about two seconds.
I remember the first time I set up an SSH key. I had to generate a "public" one and a "private" one. I knew I was supposed to keep the private one secret and share the public one, but I didn't really understand why it worked.
If someone has my public key, can't they just reverse-engineer it to get my private key?
The answer is asymmetric encryption, and it's a bit like a magic padlock.