Double validation

[ngtuna]

A masternode only signs a block if he sees two signatures of M1 and M2 in that block.

[ngtuna]

related issue: #27

[ngtuna]

So the current proposal is:

once M2 get the block created by M1, he validates his turn and then creates a sign transaction. This transaction will be broadcasting in the network as soon as possible (we need some prioritization getting involved). The other masternodes will only sign the block if two conditions are satisfied:

• Block is created by M1
• The transaction is found in transaction pool

[ngtuna]

Detailed flow:

When a new block comes in:

1) Masternode A verifies its header and body 2) Masternode A check m2 by its m1 (the creator) 3) If masternode A == m2:

• create signing transaction and broadcast it into the network
• import block into local chain. 4) if masternode A <> m2:
• waiting for the signing transaction (of m2) comes into local transaction pool
• verify that transaction
• if verification passes:
  • create signing transaction and broadcast it into the network
  • import block into local chain.
• if verification fails or the signing transaction never comes:
  • drop that block

[ngtuna]

@dinhln89 suggests to use map[blkno]tnx to trace signing transaction instead of looking into transaction pool