- Each card and ATM is given a public/private key pair.
- The public keys are signed by the bank's private key
- Every card also contains the bank's public key
When the card is inserted, the ATM asks for the card's public key
- The ATM then verifies that the card's public key was signed by the bank, using the bank's public key.
- The ATM then encrypts a block of random data with the card's public key, and asks the card to decrypt it.
- If the card successfully replies with the same random data, it has just proven that it has the private key that it claims to have
Then it's the card's turn to repeat the same process:
- It asks the ATM for its public key, verifies that it was signed by the bank, using the bank's public key.
- The card encrypts a block of data with the ATM's public key, asks the ATM to decrypt it
At this point, both the card and the ATM know that they are talking to the appropriate device. Each device can then generate a symmetrical key for that session, and encrypt it with the other device's public key, and use those keys for any further communication.
Every problem can be solved by adding a layer of indirection
The TI-83+ had the added feature of "Archiving" software, which (I surmise) wrote it to ROM
How, exactly, would a calculator write something to ROM (i.e. Read-only memory)?
Wow, I never knew that a powered-down iPod was less likely to become a projectile than one that is turned on. You've really educated me on the physics in the imaginary world that you inhabit.
And as to ignoring the safety breifing, who the F cares about the safety briefing? It's the same thing every time and it's all common sense information. Really, the nearest exit might be behind me? My seat floats? Wow, I'd be dead in a crash if I didn't hear those little nuggets of wisdom for the 7 millionth time.
If the alertness of the passengers was as important as you claim, nobody would be allowed to sleep, eat or go to the bathroom on planes; nobody would be allowed to read books, newspapers, magazines, etc.
The problem with repeating this "you don't know how many times" is that everyone already knows that it isn't true. Repeating lies over and over again just convinces people that everything you say is a lie (c.f. The Boy Who Cried Wolf)