Watchtowers
Watchtowers monitor the block chain for transactions that may cause one of their users to lose funds. If a theft attempt is detected, the watchtower acts to stop the theft, such as by sending a penalty or recovery transaction on behalf of the affected user.
The idea of watchtowers was introduced for sending LN breach remedy transactions (justice transactions) when a watchtower detected that one of their client’s counterparty had broadcast an outdated channel close transaction. Later, the name was adapted to software that monitors vaults for unvaulting transactions and which will prevent the unvaulting from completing if it violates the user’s policy.
The service provided by watchtowers allows their clients to go offline for significant amounts of time without having to worry about their funds being stolen. Watchtowers are not entrusted with the funds they monitor; their only responsibility is monitoring the block chain and broadcasting transactions. For LN, breach remedy transactions can be designed so that the watchtower receives a portion of the safeguarded funds if their services are needed.
Optech newsletter and website mentions
2024
2023
- LDK #2337 makes it easier to use LDK for building watchtowers
- LND #7069 allows a client to ask its watchtower to delete a session
- Watchtower accountability proofs
- Description of efficient watchtower use in the tunable penalty protocol
2021
2020
- LND #4782 adds watchtower client support for channels using anchor outputs
- Service proposed for storing presigned watchtower transactions
- Presentation about watchtower protocol development
- C-Lightning #3659 adds support for watchtowers
- Updated watchtower BOLT specification proposal
2019
- 2019 year-in-review: watchtowers
- Discussion about watchtowers for eltoo payment channels
- Watchtower BOLT specification proposed
- Watchtower storage costs
- LND 0.7.0-beta release with initial watchtower support
- LND PR #3133 adding support for altruist watchtowers
- LND PR #2618 implementing private watchtower support
- LND PR #2448 adding a standalone watchtower
- LND PR #2439 adding a default policy for the watchtower
2018
- LND PR #2124 adding support for detecting and using onchain spends
- LND PRs #1535 and #1512 adding server-side communication for watchtowers
- LND PR #1543 adding watchtower version 0 encoding and encryption
See also
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