Windows 8 Phone - access to NFC reader?

问题:

Short question: Can I read credit card information with a NFC capable Windows Phone 8?

Long question: How does NFC with credit cards exatly work? The card (or the phone with wallet function) receives a request via NFC and replies with the cleartext credit card information in some standardised format? The Wallet option then aditionally still props some comfirmation dialog before broadcasting the credit card information?

Or is there some handshake encryption going on before hand? Or is there some credit card specific secret code safeguarding the commuincation? Or is there some overlay protocol on NFC for payment? NFC ist just pushing a string over the air as far as know?

If it works, as I think it works, can I tell a Windows 8 Phone, through preferably C#, to read credit card information and display it to me (if the credit card has a chip inside)? Or does maybe Windows Phone 8 disallow access to the NFC reader, or some mystic payment protocol (if such a thing exists). My short web search was very vage on technical details, especially with some sites talking about carrier support for wallet systems, as if some keys would be fetched from somewhere in the web to secure the transactions? I can't really image something like that being standardised accross all credit card issuers.

Can someone give technical insight the way credit card data is transfered and if you can program a phone to read such data.

回答1:

Contactless credit/debit cards certainly do use NFC (mainly ISO 14443-A, some mainly in France are ISO 14443-B), and their communication protocols follow an industry standard called EMV which has public specs available here: http://www.emvco.com/specifications.aspx?id=223 The cards speak the same EMV both over NFC/contactless as well as through the contact chip (eg the gold thing you insert into a reader) though payment networks tend to do things slightly differently depending on which interface is used (eg sometimes PIN not required via contactless for low amounts, whereas contact might always require a PIN). Also, certain aspects of the protocols are proprietary to the payment networks so the EMV specs don't fully describe everything.

If you search around there are various sites that give some examples of how to communicate with credit/debit cards some over NFC others with an insert chip card, but typically the commands will work the same regardless of the interface. You can buy a USB smart card reader that will do both NFC and insert/contact for http://blog.saush.com/2006/09/08/getting-information-from-an-emv-chip-card/

For Windows Phone you also can talk with credit cards as long as you have a Lumia 830/730/735 etc as the older devices (even the Lumia 930) have an older NFC chip where the driver doesn't support the smart card APIs. You can use the sample code here: https://nfcsmartcardreader.codeplex.com/ to learn how to send/receive APDU commands/responses to NFC cards though that project doesn't specifically have the commands you need for a credit card (though that other link does have the APDUs you need).

And credit cards generally all will let you read their PAN (the account number printed on the front), expiry date, and in some countries even the cardholder name (though in the US for privacy most banks tend to not expose it, instead returning stuff like "VALUED/CARDHOLDER" as the name) without any encryption or keys. It will not however return the CVV2 code printed on the back of the card, which is generally required by merchants to be able to place orders on the internet, and it also generally does not let you clone the card since there is dynamic/encrypted data required to do card present transactions at a physical merchant.

回答2:

Short answer: No. It's unlikely Credit card would work with WP8.

Long answer:

1. RFID vs. NFC: As far as I know most credit cards don't have NFC. They have RFID. Which one could say it's a "predecessor" technology to NFC. RFID is mostly non-standardized, has longer range than NFC and only supports one-way communication. Whereas NFC is an evolving standard, can be used in 2cm-4cm range and supports two-way communication. So, WP8 does not support RFID but it does support NFC.
2. RFID on WP8: All that being said, there's a chance that WP8 could identify some RFID tags. You might be able read byte[] from specific RFID tags in specific WP8 phones. Obviously, that's not recommended.
3. Secure NFC: One last thing is that some very exclusive partners in some very specific regions will have access to "Secure NFC". Secure NFC is a superset of NFC and adds the feature to store & transmit secure information via NFC from WP8. For example Secure NFC can store a Credit Card number or a bank account number as part of the WP8 Wallet. However, That will only work in regions where the mobile operator issues a "Smart SIM" (SIM capable of running applets), where the developer can author Java based Smart SIM applets, where the developer has an agreement with the mobile operator to deploy those applets over-the-air, where those WP8 apps have been cleared with Microsoft for the WP8 store and where there are dedicated retail HW terminals that can read them.

回答3:

Sorting out a bit of the above answer of JustinAngel:

• RFID is not a predecessor technology of NFC
• RFID covers various frequency bands of Radio Frequency Communication (e.g. HF and UHF)
• NFC is Near Field Communication and usually covers HF (13.56 MHz)
• Many standards fall under HF NFC: ISO14443-4, ISO15693, FeliCa, ISO18092, .....
• NFC Forum is trying to unify things and uses NDEF messages to exchange semantic messages
• contactless payment on credit cards is based on a contactless smartcard layer.
• WP8 allows only exchange of NDEF messages
• WP8 does not allow exchange on the contactless smartcard layer (ISODEP==L4==(T=CL))
• see the windows proximity api for details or http://developer.nokia.com/Community/Wiki/Use_NFC_tags_with_Windows_Phone_8
• Android however gives access to this ISODEP layer
• I don't know what credit card information could be retrieved from an app. There is a secure element involved which handles cryptography and stuff. I don't think detailed information on Mastercard payPass or VISA payWave is freely available

回答4:

Can I read credit card information with a NFC capable Windows Phone 8?

No, you cannot do that. NFC API on Windows Phone 8 is very limited.

May be Wallet API could help you somehow with your project, but this is not about NFC. Also you could try to use Android devices with NFC, they have more powerful NFC API than WP8.