Android HCE: An intro into the world of NFC

Android HCEAn intro into the world of NFC

Neel Rao

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NFC - Intro

NFC (Near Field Communication) is a form of short range (a few cms) wireless comm.

Powered through modulated magnetic field

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NFC - Intro

NFC Smart Cards can have functional applets (Java Card)

Capable of storage, reading, crypto, etc.

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NFC - Intro

Throughput is low, but useful for transferring URLs or small chunks of data (106-424 kbit/s)

Action is very specific, the short range makes the intent clear

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NFC - Smart Phones

With smart phones the next logical step was to move the NFC hardware inside

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NFC - Secure Element?

Basically is equivalent to taking the hardware in a NFC card and putting it in your phone.

Hardware component with built in “applets” and resilient tamper-proofing.

Two types UICC (SIM card) and eSE (NFC controller)

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SE-Based Architecture

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Secure Element - Tradeoffs

Payment applets on the SE contain sensitive data and require increased security

Limited space on the SE

Ownership of Secure Element is contentious

Solution: Restrict access to the SE. There are no public Android APIs to access SE

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What is Host Card Emulation?

HCE allows Android to emulate a NFC smart card without requiring a secure element

This enables innovation for many new use cases such as building access, mass transit and loyalty

Works alongside other card emulation modes on secure element based solutions

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HCE Architecture

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HCE Development - Two Stages

App selection: Which app should be selected when you tap your phone to a reader?

Data transfer: How do you actually send and receive data to and from the NFC reader?

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HCE - App Selection

NFC Reader

App 1 App 2 App 3

?

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HCE - AID Registration

NFC Reader

App 1 App 2 App 3

F506

AID: F506

F123F932

F999 F007

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AID Querying

NFC Reader

App XAID: F56

Select AID “F12”

“Not found”

Lookup, resolve to app X Select AID “F56”

Lookup, appnot found

Android OS

Select AID “F56”

OK + Response Data

Command

Response

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Conflict resolution - AID Categories

App X App Y

AID F123

AID F078

AID F123

AID F234

AID Categories

Default

Select AID F123

If conflict, then automatically choose “Default” app

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Conflict resolution - AID Categories

App X

App Y

Complete action with:

Select AID F123

If no “Default”, then ask user

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Conflict resolution - AID Categories

Two AID Categories: Payments & Other

Payments category has a system UX so users can choose their default wallet app.

With a default wallet app, users can pay with one tap rather than selecting wallet at payment time

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Payments!

An example of how AID selection works at payment terminals

Consumers can have multiple wallet/loyalty apps, and multiple cards within each app.

How does AID selection work in this case?

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Payments -- Naïve AID Selection

NFC Reader

Wallet XAID: F56

Select Visa AID

Lookup, resolve to Wallet X

Not Found

Android OS

Select AID “F56”

Select MasterCard AID

Select Discover AID

Select AmEx AID

Not Found

Not Found

Not Found

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Payments -- The Fast Method (EMV)

NFC Reader

Wallet XAID: F56

Android OS

What Payment AIDs do you have?

I have “F56”, “F12”

Lookup, resolve to app X

Select F56Select AID “F56”

Wallet AAID: F12

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AID Selection - Review

Apps register one or many AIDs in manifest.

Readers select apps by querying with AIDs.

Conflicts either resolved automatically (payments) or by user

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Sending + Receiving Data

Use a Service that is always listening for NFC.

Two modes: you can indicate if you need the screen to be unlocked or not. Locked mode can overlay UI on lock screen.

For example with a wallet app, you might want the phone to be unlocked for security.

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Sending + Receiving Data

public class MyHostApduService

extends HostApduService {

public byte[] processCommandApdu(byte[]apdu,

Bundle extras) {}

public void onDeactivated(int reason) {}

}

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public byte[] processCommandApdu(byte[] apdu,

Bundle extras) {}

Return byte[ ] which get sent to the reader

Receive byte[ ] when function gets called

Sending + Receiving Data

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public byte[] processCommandApdu(byte[] apdu,

Bundle extras) {}

Since this is called on the main thread, you should return ASAP. If you need to do processing, return null. Then call sendResponseApdu() later.

Sending + Receiving Data

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Reader APIs

HCE lets your phone act as a NFC card

With the Reader APIs, your phone can also act as an NFC terminal

Testing is convenient since you can use two phones to simulate a NFC card and a reader

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Use Cases - Loyalty

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Use Cases - Building access

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Use Cases - Transit

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NFC - The Future

400M NFC smart phones shipped in 2014.

By October 2015, Chip & Pin cards will replace regular cards in the US. This means new terminals which probably have NFC

By 2017, 32% of all actively used smart phones will have NFC (2.1B phones)

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Conclusion

HCE allows an NFC reader to directly communicate with your Android app with just a tap

With the Reader APIs, your phone can also act as an NFC terminal

NFC has the potential to be really big, but we need developers like you for novel apps!

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Questions?

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Thanks!Stop by the NFC Forum booth #401 to learn more about the possibilities of developing with NFC.

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