Why not use regular Credit and Debit cards ?
I think you would have great difficulty making a system that is secure and which both you and the users can have confidence in.
Users could tamper with "value" stored on their device (in the privacy of their bedrooms) and you could tamper with "value" stored on the server.
With local bar I mean 'youth club'. It's a place for friends to come and have fun together. A regular debit card system is to expensive (monthly cost) for us. At the moment we have this 'booze cards'. It's just a paper with 10 consumptions that they can buy. Everythime they drink/eat something, they get a stamp. We want to replace this with RFID cards.
About the value stored on the card; I Would like to store the value on the card AND on the Arduino (SD Card?). If the values don't mach, we will see a message so that we can investigate the issue. Also, the 'money' on the card will be very small. I Was thinking about a maximum of 20 euro. also, they can't tamper the value if I encrypt it?
Storing the data on the server is better. If someone looses an RFID card without data, a new one can be issued, with no loss of credit. If the data is on the RFID card, loosing the card means loosing the credit linked to that card.
Finding such a card, with no data, could mean that the card is useless.
We are going to tell our members that the data IS stored on the card and if they loose it the money on it WILL BE GONE. We are a small association with a limited amount of money. We don't want to be handing out new cards every week. It is their responsibility.
I Was Googling some RFID readers, but I'm not sture which one to use. Should I buy an USB Reader/Writer, or should I buy an Arduino RFID module?
About the RFID cards; the MIFARE Classic 1K should be able to store 1K of data, what should be enough for the balance on the card.
And last but not least; What Arduino do I need?
- I need to be able to connect an LCD to it to see the current balance.
- I Need to connect a keyboard (numeric + return key) to reload the card and the enter the price of the consumption.
- I Need to save some data on the arduino (to match it with the data on a specific card). I Was thinking about an SD slot with an SD card, if possible.
- An RFID Module, or an USB RFID (Read/Write).