Enforce centralized gas prices

[haasted]

Gas prices for the network is currently controlled by the authority account, and enforced by the standard implementation of the em-ledger software.

It's possible for a validator to run a version of the em-ledger software that ignores the gas prices set by the authority account. There is currently no penalty for this.

This behaviour can be turned into a network offense, that could lead to either jailing or slashing. Other nodes could inspect committed blocks to see if the transaction fees were enforced. It should be investigated whether Tendermint's evidence and byzantine validator mechanisms can be used.

[alpe]

As a simple solution you can have an ante handler that would reject any TX with fees < min fee as opposite to slashing. There is some ongoing discussion about dynamic min fees going on in the community. You may want to check that as well.