I’ve been playing with some NFC apps, and set up a few NFC ‘patches’ to perform certain tasks, and I’ve been thinking… Is there a way of reading the information that a NFC enabled credit card actually sends to a NFC PayPass terminal? The goal would be to build an app which somewhat parallels google wallet in as much as I can load my credit card data into my phone and tap it on Paypass terminals to pay (Google Wallet isn’t available in Australia without some hackery).
Anyone knowledgeable in this field?
Not really. Card<->reader communication is usually encrypted and the key is derived every time using a challenge-response protocol. Additionally, if you want to communicate with the payment applet, you need to know both the secure channel key and the protocol.
On the other hand, even if you patch Android to support card emulation, you still need the card manager key (or something similar) to be able to install applets (or write files), so you cannot install your own.
In short, unless you are using Google wallet or have access to the secure element key(s), you can only use the NFC chip to read and write tags.