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From: Jeff Garzik <jgarzik@bitpay.com>
Date: Tue, 15 Jul 2014 11:11:25 -0400
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To: Luke Dashjr <luke@dashjr.org>, Mike Hearn <mike@plan99.net>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Bitcoin address TTL & key expiration?
Precedence: list

On Tue, Jul 15, 2014 at 10:48 AM, Luke Dashjr <luke@dashjr.org> wrote:
> They can already do this. It's perfectly valid for wallets/services to ignore
> (and not consider as payment) transactions using an address more than once.
> There might be race attacks if this is implemented in an immediate fashon
> (attacker transaction gets mined first to kill a payment), but should be
> pretty safe after a few blocks.

Sure it's valid.  However, few users will appreciate "you ignored my
deposit" as a feature.

Payment protocol just doesn't well the use cases of,
* an on-going payment stream from, e.g. Eligius to coinbase
* deposit addresses and deposit situations

-- 
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc.      https://bitpay.com/