For pbft, threshold is wrong.

[harsh-98]

https://github.com/dedis/paper_17_randomness/blob/master/protocols/byzcoin/pbft/pbft.go#L85.

The number of nodes be n, and faulty be f. Condition is :

n>=3f+1

(n-1)/3>=f

n-(n-1)/3 <= n-f = number of non-faulty nodes. #Threshold

(2n+1)/3 <= n-f #threshold

But the formula you have used is:

ceil( (n*2/3) ) which is wrong.

Correct one is ceil( (n*2+1)/3 ).

Example, let n=6, then f=1 and threshold is 5.

But for your formula threshold comes to be 4.