Author: Mark Friedenbach 2017-09-27 19:03:44
Published on: 2017-09-27T19:03:44+00:00
In a recent discussion on the bitcoin-dev mailing list, Peter Todd proposed adding an expiration time to the new BIP173 address format to help combat the re-use of old addresses, which can lead to privacy and operational issues. Todd suggests that wallets should consider addresses invalid as a destination for funds after the expiration time is reached. He also acknowledges that the entire notion of addresses is flawed from a user point of view and should be more like "payment codes" that are valid for payment for a short period of time. To implement this proposal, Todd suggests two options for resolution: hour or month. Hour resolution would provide 2^24 hours or 1914 years, while month resolution would provide 2^16 months or 5458 years. Both options work well at the UI level regardless of timezone, but hour-level precision could make it easy for services like exchanges to use addresses with relatively short validity periods to reduce the risks of losses after a hack. The proposal may raise questions about UI and terminology, and some thought needs to be put into this aspect. Todd concludes by noting that every address should have an expiry, and no address should be considered valid longer than anticipated lifetime of the underlying cryptosystem in any case. Additionally, he suggests using the 17 bit relative time format used in CSV as an offset from the birthdate of the address, which would mean that addresses cannot last more than a year without user override. This could be extended by a few bits if necessary.
Updated on: 2023-06-12T19:08:17.131098+00:00