Message-ID: <54D4237E.5@voskuil.org>
Date: Thu, 05 Feb 2015 18:14:22 -0800
From: Eric Voskuil <eric@voskuil.org>
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To: Andy Schroder <info@AndySchroder.com>, 
	bitcoin-development@lists.sourceforge.net
References: <544174F8.1050208@AndySchroder.com>
	<54D3FEE9.70502@AndySchroder.com> <54D40C7D.8090804@voskuil.org>
	<54D41B90.2010208@AndySchroder.com>
In-Reply-To: <54D41B90.2010208@AndySchroder.com>
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Subject: Re: [Bitcoin-development] Two Proposed BIPs - Bluetooth
 Communication and bitcoin: URI Scheme Improvements
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Agree, range is not an issue. The trade-off is in battery vs. total
time, which would be influenced primarily by the battery sensitivity of
the platform. I'll send you a note to follow up.

e

On 02/05/2015 05:40 PM, Andy Schroder wrote:
> Hello,
>=20
> I personally would prefer as low of range as possible for this bluetoot=
h
> application considering the connection is not yet encrypted (mentioned
> below), and even if it were, it seems like it is always going to be
> better in case there is some vulnerability. From my testing with a
> bluetooth radio inside my metal cabinet, the range is ~5 meters, which
> is more than enough.
>=20
> However, the connection is actually a bit slow when the whole
> certificate chain is included (~3-4s). You can sort of see this in my
> video (http://youtu.be/kkVAhA75k1Y?t=3D7m39s). A lot of the time is
> actually spent verifying the signature, and I'm not sure how much of it=

> is doing the fetching (I haven't done any detailed timings using "adb
> logcat" and looking at the log entries), but I do know it is a little
> slower than an HTTPS payment request fetch over wifi (~2-3s). The reaso=
n
> I know most of the time is the signature verification is because an
> HTTPS payment request fetch over wifi and verification using breadwalle=
t
> on apple is much faster (<1s) than HTTPS payment request on bitcoin
> wallet on android (apparently apple has a significantly more optimized
> signature verification algorithm). Bottom line is that there may be ~1s=

> time transferring the data with this current bluetooth connection. Not
> sure how slow it will be with the BLE connection. Time is everything in=

> a point of sale application.
>=20
> So, I guess what I am saying is it seems like the lower speed and range=

> gain with bluetooth low energy are not a benefit in my opinion. I'm not=

> sure that the latency gain will be a benefit either unless the speed
> issues I am noticing with regular bluetooth are actually a latency issu=
e
> with just getting the connection established, or actually transmitting
> the payment request data. How much power is going to be used for just a=

> few second payment? It's not like the bluetooth connection is maintaine=
d
> for a long time like it may be in other non bitcoin use cases.
>=20
>=20
> Where is a more appropriate place to discuss the other issues you have
> at length?


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