<ul><li>If an attacker attempts a double spend by undoing a transaction after it has been settled, one possible defense strategy is a child-pays-for-parent transaction.</li><li>This involves the victim broadcasting a child transaction with an extremely large fee attached.</li><li>The hope is that honest miners will see the invalidity of the child transaction on the longest chain, but its validity on the shorter chain.</li><li>By inducing more hash power to mine on the shorter chain, the high fees would overpower and undo the attacker's re-org.</li></ul>

Child-pays-for-parent as a defense against a double spend: feasible?

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