Watchtowers A Lightning channel partner can cheat by broadcasting an old commitment tx. To detect and revert, the honest party must broadcast a "justice tx" within blocks. Watchtowers do this monitoring on your behalf when you're offline. Threat model Watchtower is untrusted for fund custody. It only learns: - Channel txid (from you provide). - Encrypted blob (the justice tx). It does NOT learn: - Channel balance. - Counterparty identity. - Payment activity. If the watchtower colludes with the cheating party, it gains nothing (it doesn't have funds; it only fails to broadcast → channel partne…