digraph G {
  0 [label="Root\nH(A || H(B || C))"]
  0 -> A
  A [label="A\nskip"]
  0 -> 1
  1 [label="Node\nH(B || C)"]
  1 -> B
  B [label="B\nskip"]
  1 -> C
  C [label="C\nverify"]
}