Casper CBC



  • chain-based POS (mimics POW & build a chain of blocks & simulates mining)
  • BFT based POS (Tendermint, Algorand)


  • 如何惩罚坏人 -> solve "nothing at stake” problem -> validator’s entire deposit
  • validators如何更新 -> validator set to change over time
  • 如何应对攻击
    • long range revision attacks,
    • 1/3 validators drop offline


  • first version of Casper a hybrid PoW/PoS system
  • future versions converting the block proposal into a some kind of PoS round-robin block signing scheme.
  • simple version : a fixed set of validators and a proposal mechanism which produces child blocks of existing blocks, forming an ever-growing block tree. the root of the tree is the “genesis block”.
  • Casper’s job is to choose a single child from each parent, thus choosing one canonical chain from the block tree. (canonical chain!)



Vlad Zamfir at Ethereum ÐΞVcon-0 with Gavin Wood, Berlin, Nov. 2014

screen shot 2017-11-03 at 8 24 26 pm