[bitcoin-dev] consensus rule change for TX fee safety

[Alice Wonder <alice@librelamp.com>]

I think the next hard fork should require a safety rule for TX fees.

https://blockchain.info/tx/6fe69404e6c12b25b60fcd56cc6dc9fb169b24608943def6dbe1eb0a9388ed08

15 BTC TX fee for < 7 BTC of outputs.

Probably either a typo or client bug.

My guess is the user was using a client that does not adjust TX fee, and 
needed to manually set it in order to get the TX in the block sooner, 
and meant 15 mBTC or something.

I suggest that either :

A) TX fee may not be larger than sum of outputs
B) TX fee per byte may not be larger than 4X largest fee per byte in 
previous block

Either of those would have prevented this TX from going into a block.

Many people I know are scared of bitcoin, that they will make a TX and 
make a mistake they can't undo.

Adding protections may help give confidence and there is precedence to 
doing things to prevent typo blunders - a public address has a four byte 
checksum to reduce the odds of a typo.

This kind of mistake is rare, so a fix could be included in the coming 
HF for the possible July 2017 block increase.

Thank you for your time.

Alice Wonder