Android HCE: An intro into the world of NFC

Android HCE
An intro into the world of NFC
Neel Rao

NFC - Intro
NFC (Near Field Communication) is a form of
short range (a few cms) wireless comm.
Powered through modulated magnetic field
Google Confidential and Proprietary

NFC - Intro
NFC Smart Cards can have functional applets
(Java Card)
Capable of storage, reading, crypto, etc.

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

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

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)

SE-Based Architecture

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

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

HCE Architecture

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?

HCE - App Selection
App 1 App 2 App 3
?
NFC Reader

HCE - AID Registration
F506
App 1 App 2 App 3
NFC Reader
AID: F506
F123
F932
F999 F007

AID Querying
NFC
Reader
App X
AID: F56
Select AID “F12”
Android
OS
“Not found”
Lookup, app
not found
Lookup, resolve to app X
OK + Response Data
Command
Response

Conflict resolution - AID Categories
If conflict, then
automatically choose
“Default” app
AID Categories
App X App Y
AID F123
AID F078
AID F123
AID F234
Default
Select AID
F123

If no “Default”, then ask
user
Complete action with:
App X
App Y
Select AID
F123

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

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?

Payments -- Naïve AID Selection
NFC
Reader
Select MasterCard AID
Select Discover AID
Select AmEx AID
Wallet X
AID: F56
Select Visa AID
Android
OS
Not Found
Lookup, resolve to
Wallet X
Not Found
Not Found
Not Found

Payments -- The Fast Method (EMV)
NFC
Reader
Wallet X
AID: F56
Android
OS
What Payment
AIDs do you have?
I have “F56”, “F12”
Lookup, resolve
to app X
Select F56
Wallet A
AID: F12

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

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.

public class MyHostApduService
extends HostApduService {
public byte[] processCommandApdu(byte[]apdu,
Bundle extras) {}
public void onDeactivated(int reason) {}
}

public byte[] processCommandApdu(byte[] apdu,
Bundle extras) {}
Return byte[ ]
which get sent to
the reader
Receive byte[ ]
when function
gets called

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.

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

Use Cases - Loyalty

Use Cases - Building access

Use Cases - Transit

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)

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!

Questions?

Thanks!
Stop by the NFC Forum booth #401 to learn more
about the possibilities of developing with NFC.
Enter your name for a chance to win a Sony
Action Cam with GPS!

Android HCE: An intro into the world of NFC

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Android HCE: An intro into the world of NFC