if my ATM pin is a secret, how does the machine know it?

[justseyi]

Here’s the thing: the bank doesn’t actually store your PIN anywhere in its system. That would be like putting everyone’s house keys in one basket — way too risky.

So how does the ATM know if you typed the right thing?

When you first set your PIN (say, 1234), the bank runs it through a process called hashing. Think of it like pounding yam: once the yam is pounded into swallow, you can’t turn it back into the raw yam chunks.

So your PIN (1234) goes in, and what comes out is something wild like:
a665a45920422f9d417e… — a long string of random-looking letters and numbers.

That scrambled version is what the bank keeps.

Now fast-forward to you at an ATM or POS. You type in your PIN. The machine runs what you typed through the same pounding (hashing) process. Then it compares the result to what’s stored.

If the two hashes match → correct PIN → take your money.
If they don’t → decline.

Even if hackers break into First Bank’s or GTBank’s database, all they’ll see are those scrambled codes. They can’t reverse them into real PINs — the math just doesn’t allow it.

 

[Divine]

Una day think go far

[Author]

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