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From: Jeff Garzik <jgarzik@bitpay.com>
Date: Tue, 15 Jul 2014 04:00:41 -0400
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Subject: [Bitcoin-development] Bitcoin address TTL & key expiration?
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Proxying another's idea, from CoinSummit.
The request: It would be useful to limit the lifetime of a bitcoin
address. Intentionally prevent (somehow) bitcoins being sent to a
pubkey/pkh after the key expires.
You could append "don't ["permit"|confirm] after X [time|block]" to
the address I suppose. The metadata would not be digitally signed,
but it would be hash-sealed. As "address" is a client-side notion,
wallet clients would be the ones enforcing such a rule.
Bitcoin protocol of course knows about keys, and key expiration is a
well known and useful concept in public key cryptography. The best
insertion point in the protocol for key expiration is an open
question, if it's even a good idea at that level at all. Some flag
"no more TxOuts exactly like this [after X block?]"?
I readily admit I don't have good answers, but it does seem valuable IMO to
* Prevent users from accidentally sending to an "expired" TxOut/pkh.
This happens in the field.
* Discourage address reuse
* Enable sites that generate lots of keys to rotate ancient keys off
their core systems. (HD wallets mitigate this)
--
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc. https://bitpay.com/
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