Message-ID: <55121611.1030104@thinlink.com>
Date: Tue, 24 Mar 2015 18:57:37 -0700
From: Tom Harding <tomh@thinlink.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64;
	rv:31.0) Gecko/20100101 Thunderbird/31.5.0
MIME-Version: 1.0
To: Bitcoin Development <bitcoin-development@lists.sourceforge.net>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: [Bitcoin-development] Address Expiration to Prevent Reuse
Precedence: list

The idea of limited-lifetime addresses was discussed on 2014-07-15 in

http://thread.gmane.org/gmane.comp.bitcoin.devel/5837

It appears that a limited-lifetime address, such as the fanciful

address = 4HB5ld0FzFVj8ALj6mfBsbifRoD4miY36v_349366

where 349366 is the last valid block for a transaction paying this 
address, could be made reuse-proof with bounded resource requirements, 
if for locktime'd tx paying address, the following were enforced by 
consensus:

  - Expiration
    Block containing tx invalid at height > 349366

  - Finality
    Block containing tx invalid if (349366 - locktime) > X
    (X is the address validity duration in blocks)

  - Uniqueness
    Block containing tx invalid if a prior confirmed tx has paid address

Just an an idea, obviously not a concrete proposal.