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Since US cards are "dumb", the ATM doesn't need to send PIN information to it. The ATM card # can be stolen, however, that's not enough to complete the transact
by kqr2 16y ago
Since US cards are "dumb", the ATM doesn't need to send PIN information to it. The ATM card # can be stolen, however, that's not enough to complete the transaction.
- gbrindisi 16y agoTalking about old mag stripe card, the system used to authenticate the transaction is this: 1. The account number is crypted in DES (ora a variant) with a PIN key, the cryptogram is then decimalized and the first 4-5 digit extracted to obtain the so-called natural PIN. 2. The user then can change is PIN by using an offset: user PIN + offset = natural PIN. 3. Account number and offset are stored in the card. 4. The ATM knows the PIN key (wich is a shared key common to all the ATMs system of a certain bank) and when a card is inserted the ATM calculates the natural PIN from the account number. Then it verifies the PIN number: if user PIN = natural PIN + offset then SUCCESS