Proof of Stake: Which Node chooses the next block validator?

Question

I understand that the next block validator is chosen randomly (weighted by stake) from a group of validators / stakers, but how is this done decent-rally? Which node or nodes do this random choosing, and wouldn't the choice of the next block validator be different for each node if it was chosen randomly?

Answer 1

In the Emercoin (this is PoS/PoW/MM hybrid) is used following approach:

1. Every second, each UTXO can "plays game", and generate "lottery ticket" (hash).
2. If this ticket value less than the target, this UTXO can create a coinstake transaction, which close current block, and reward minter.

Thus, in common, PoS is like to PoW, but with PoW, number of "tickets" just limited by mining equipment performance only, while with PoS number of tickets limited by UTXO number and UTXO values, multiplied to "UTXO locking time".

There is impossible to create "tickets" unlimited (as same as in PoW), because of ticket value depends only from UTXO parameters, and current timestamp. No "nonce" or another "freedom" is possible.

See this line in the source code:

bool fPass = !(UintToArith256(hashProofOfStake) > bnCoinDayWeight * bnTargetPerCoinDay);