Contents

  1. Introduction
  2. History: from a paper cheque to a chip
  3. Lesson 1. The ATM processor: the same one as in the card
    1. 1.1. The idea: one processor — different machines
    2. 1.2. The idea: device addresses
    3. 1.3. The idea: the read bus — an OR of all devices
    4. 1.4. Building
    5. 1.5. Check
    6. Paste for lesson 1 (Cmd+I)
  4. Lesson 2. The keypad: 12 keys — 4 wires
    1. 2.1. The idea: the encoder
    2. 2.2. The idea: one press — one clock cycle
    3. 2.3. The idea: code × 16
    4. 2.4. Building
    5. 2.5. Check
    6. Paste for lesson 2 (Cmd+I)
  5. Lesson 3. The screen: words and digits
    1. 3.1. The idea: the screen remembers nothing
    2. 3.2. The idea: the processor writes a number, not segments
    3. 3.3. The idea: the captions light with the digit
    4. 3.4. Building
    5. 3.5. Check
    6. Paste for lesson 3 (Cmd+I)
  6. Lesson 4. The bank: card keys and balances
    1. 4.1. The idea: the bank knows the card key
    2. 4.2. The idea: the key is read at one address
    3. 4.3. The idea: money is not erased by reset
    4. 4.4. Building
    5. 4.5. Check
    6. Paste for lesson 4 (Cmd+I)
  7. Lesson 5. The card port: the slot and a random challenge
    1. 5.1. The idea: the tester is the ATM port
    2. 5.2. The idea: a slot for two cards
    3. 5.3. The idea: a random challenge
    4. 5.4. Building
    5. 5.5. Check
    6. Paste for lesson 5 (Cmd+I)
  8. Lesson 6. A session: the PIN and the card check
    1. 6.1. The idea: the card checks the PIN, not the ATM
    2. 6.2. The idea: challenge-response
    3. 6.3. The idea: the same cipher — in the ATM program
    4. 6.4. Building
    5. 6.5. Check
  9. Lesson 7. Money: the amount, the balance, the payout
    1. 7.1. The idea: the program is a session
    2. 7.2. The idea: a number from key presses
    3. 7.3. The idea: is there enough money
    4. 7.4. The idea: a number into three digits
    5. 7.5. The idea: the balance lives in the bank
    6. 7.6. Building
    7. 7.7. Check
  10. Lesson 8. A fake and the ATM as a chip
    1. 8.1. The idea: you can fake everything but the key
    2. 8.2. The idea: the ATM is a device too
    3. 8.3. Building
    4. 8.4. Check
    5. Paste for lesson 8 (Cmd+I)
  11. Summary
  12. All the parts
  13. Instructions in pictures