https://github.com/nk521/upi-lite-x

https://github.com/nk521/upi-lite-x

Last synced: 19 days ago
JSON representation

• Host: GitHub
• URL: https://github.com/nk521/upi-lite-x
• Owner: nk521
• Created: 2024-10-09T14:17:05.000Z (2 months ago)
• Default Branch: main
• Last Pushed: 2024-10-09T14:58:12.000Z (2 months ago)
• Last Synced: 2024-11-26T20:40:55.174Z (26 days ago)
• Language: Python
• Size: 1.95 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
# The NFC side of UPI Lite X

# Notes:

1. [IsoDep](https://developer.android.com/reference/android/nfc/tech/IsoDep) to get hold of PICC

2. some Ndef elements in code; not sure what they do. Can be found in Payer class.

3. A different thread to manage NFC session and take care of transactions. Keyword to search is "transceive"; https://developer.android.com/reference/android/nfc/tech/IsoDep#transceive(byte[])

4. JSON encoded data sent/recvd

5. Models are dumped in nfc_models.py

6. IsoDep manages ISO-14443-4 cards. (Not a smart card. Maybe just mimicing ultralight.)

LegRequest(VtpRequest(type="OpenContext", data={"contextData": ContextData(...).dict()}))

# The flow (AFAIU)

```mermaid

sequenceDiagram

    participant A as Sender (PCD)

    participant B as Receiver (PICC)

    Note over A,B: Possible AID selection
(relay rig fails to properly record this)

    B->>A: HandshakeModel(0, [1])

    A->>B: HandshakeModel(0, [1])

    

    B->>A: LegRequest with ContextData(...)

    A->>B: LegResponse with ContextData(...)

    

    B->>A: LegRequest with AuthData(...)

    A->>B: LegResponse with AuthData(...)

    B->>A: LegRequest with StartTransferData(...) [IMPORTANT]

    A->>B: LegResponse with RequestValue(...)

    

    B->>A: LegRequest with TransferValue(...)

    A->>B: LegResponse with TransferValue(...)

    Note over A,B: vvv These doesn't matter. vvv

    B->>A: LegRequest with empty VtpRequest of type "ContextClose"

    A->>B: LegResponse with empty VtpRequest of type "ContextClose"

```