What is Nostr?
Andreas Schildbach [ARCHIVE] /
npub1xg2…dsv7
2023-06-07 15:14:51
in reply to nevent1q…uxv9

Andreas Schildbach [ARCHIVE] on Nostr: 📅 Original date posted:2014-03-07 📝 Original message:On 03/07/2014 10:26 AM, ...

📅 Original date posted:2014-03-07
📝 Original message:On 03/07/2014 10:26 AM, Johannes Zweng wrote:

> In current phone implementations, the screen must be on already for NFC
> to be active. Also it must be unlocked, although I certainly hope future
> OSes will allow payment apps on the lock screen, just like they allow
> music players.
>
> Just a small input to this point:
> On Android 4.4 the new host card emulation (HCE) feature (aka: the phone
> emulates a ISO-DEP Smartcard and processes ISO7816-4 APDU commands like
> a Smartcard would do) only works when the display is on, but even when
> the screen is locked (can be changed with "android:requireDeviceUnlock"
> in Manifest). See here for detailled
> specification: http://developer.android.com/guide/topics/connectivity/nfc/hce.html
>
> Using the HCE API on Android 4.4 also has the beauty that any app that
> registers itself for HCE and sets its category to CATEGORY_PAYMENT in
> the Manifest automatically shows up in Adroid's system settings under
> "Tap & Pay" (where a user would expect payment applications).

Thanks for the pointer! Good to hear there is finally a decent
documentation for HCE.

Good news: HCE offers the required dispatch ability -- they call it AID
(Application ID).

Bad news: It seems - at least CATEGORY_PAYMENT - very credit card centric.

HCE seems to cover only the payer side. I wonder if there is also an API
for "reader emulation" which we would need for apps to support the payee
side.

Since Android 4.4 market penetration is quite far off, I suggest we
focus on the already established NFC payment protocol(s) for now, it
works pretty well. I will investigate into IsoDep and HCE and see if we
can make it enhance usability.

Interesting side note: They recommend messages transmitted via NFC to
not exceed 1 KB in order for a snappy experience. This (again) questions
usage of bulky X.509 certificates in our payment request messages.
Bitcoin Wallet currently does not sign payment requests, so I could not
try how it would feel.
Author Public Key
npub1xg2m84malu0cfm4444r0kysx4rgk27e75aj6sz6538kw8fcz627qeadsv7