EIP-6110: In-protocol deposits

[jimmygchen]

Description

See Consensus Specs for more details: ethereum/consensus-specs#3177

EIP: https://eips.ethereum.org/EIPS/eip-6110

PoC implementations

PoC design & scope:
https://hackmd.io/@n0ble/in-protocol-deposits-poc

@kevinbogner is implementing a PoC in Lighthouse here:
kevinbogner#3

pairing with this Besu fork:
https://github.com/naviechan/besu

[jimmygchen]

This has been implemented as part of #5741