MESS confirmation calculator

On a node running MESS, a reorganization needs more total difficulty the older the block where the two chains split. This calculator shows how much more. Exchanges and other integrators can use it to see what a confirmation policy asks of an attacker.

Calculator¶

Required ratio by time¶

How it is computed¶

MESS compares the two chains from the block where they split, their common ancestor. With x the number of seconds from the common ancestor’s timestamp to the head’s timestamp, capped at 25,132:

1

ratio = (128 + (3*x^2 - 2*x^3 // 25132) * 3840 // 25132^2) / 128

// is integer division. The node accepts the reorganization only if the competing chain added at least ratio times the difficulty its own chain added since the split. The ratio starts at 1 and reaches its cap of 31 at 25,132 seconds, just under 7 hours. The calculator follows ecbp1100PolynomialV in core/blockchain_af.go.

Reading it as hashrate¶

When both chains are mined over the same stretch of time, the difficulty each adds is roughly proportional to its hashrate. So the ratio is roughly the multiple of the rest of the network’s hashrate an attacker needs to replace blocks that old on nodes running MESS. Without MESS, any chain with more total difficulty wins.

Limits¶

• It applies only where MESS is in force. A node switches MESS off when it has fewer than five peers or its head goes stale: When the node switches it off by itself. admin.ecbp1100Status() shows whether it is on.
• The time comes from block timestamps, which miners set, not from your clock.
• The hashrate reading is an approximation. Difficulty adjusts block by block, so a chain’s difficulty tracks its hashrate only over many blocks.
• Nodes without MESS follow the chain with the most total difficulty.