Creation of a formal verification system from scratch. Part 1: character virtual machine in PHP and Python

1. Combinatorial explosion, since formal verification ultimately rests on P = NP
2. Handling calls to the file system, networks and other external storage is more difficult to verify
3. Bugs in the specification, when the customer or programmer conceived one thing, but did not accurately describe it in the statement of work.

#Извлекаем положение всех объектов из блокчейна
let contract = tx.sender
let human= extract(getInteger(contract,"human"))
let wolf= extract(getInteger(contract,"wolf"))
let goat= extract(getInteger(contract,"goat"))
let cabbage= extract(getInteger(contract,"cabbage"))
#Это так называемая дата-транзакция, в которой пользователь присылает новые 4 переменные.
#Контракт разрешит её только в случае если все объекты останутся в сохранности.
match tx {
case t:DataTransaction =>
   #Извлекаем будущее положение всех объектов из транзакции
   let newHuman= extract(getInteger(t.data,"human")) 
   let newWolf= extract(getInteger(t.data,"wolf"))
   let newGoat= extract(getInteger(t.data,"goat"))
   let newCabbage= extract(getInteger(t.data,"cabbage"))
   #0 обозначает, что объект на левом берегу, а 1 что на правом
   let humanSide= human == 0 || human == 1
   let wolfSide= wolf == 0 || wolf == 1
   let goatSide= goat == 0 || goat == 1
   let cabbageSide= cabbage == 0 || cabbage == 1
   let side= humanSide && wolfSide && goatSide && cabbageSide
   #Будут разрешены только те транзакции, где с козой никого нет в отсутствии фермера.
   let safeAlone= newGoat != newWolf && newGoat != newCabbage
   let safe= safeAlone || newGoat == newHuman
   let humanTravel= human != newHuman 
   #Способы путешествия фермера туда и обратно, с кем-то либо в одиночку.
   let t1= humanTravel && newWolf == wolf + 1 && newGoat == goat && newCabbage == cabbage 
   let t2= humanTravel && newWolf == wolf && newGoat == goat + 1 && newCabbage == cabbage
   let t3= humanTravel && newWolf == wolf && newGoat == goat && newCabbage == cabbage + 1
   let t4= humanTravel && newWolf == wolf - 1 && newGoat == goat && newCabbage == cabbage
   let t5= humanTravel && newWolf == wolf && newGoat == goat - 1 && newCabbage == cabbage
   let t6= humanTravel && newWolf == wolf && newGoat == goat && newCabbage == cabbage - 1
   let t7= humanTravel && newWolf == wolf && newGoat == goat && newCabbage == cabbage
   let objectTravel = t1 || t2 || t3 || t4 || t5 || t6 || t7
   #Последняя строка в разделе транзакции описывает разрешающее транзакцию условие.
   #Переменные транзакции должны иметь значения 1 или 0, все объекты должны
   #быть в безопасности, а фермер должен переплывать реку в одиночку 
   #или с кем-то на каждом шагу
   side && safe && humanTravel && objectTravel
case s:TransferTransaction =>
   #Транзакция вывода средств разрешена только в случае если все переплыли на другой берег
   human == 1 && wolf == 1 && goat == 1 && cabbage == 1
#Все прочие типы транзакций запрещены
case _ => false
}

cabbage: extract ( getInteger ( contract , "cabbage" ) )
goat: extract ( getInteger ( contract , "goat" ) )
human: extract ( getInteger ( contract , "human" ) )
wolf: extract ( getInteger ( contract , "wolf" ) )
fState: human== 1 && wolf== 1 && goat== 1 && cabbage== 1
fState: 
wolf: 
goat: 
cabbage: 
cabbageSide: cabbage== 0 || cabbage== 1
human: extract ( getInteger ( contract , "human" ) )
newGoat: extract ( getInteger ( t.data , "goat" ) )
newHuman: extract ( getInteger ( t.data , "human" ) )
goatSide: goat== 0 || goat== 1
humanSide: human== 0 || human== 1
t7: humanTravel && newWolf== wolf && newGoat== goat && newCabbage== cabbage
t3: humanTravel && newWolf== wolf && newGoat== goat && newCabbage== cabbage + 1
t6: humanTravel && newWolf== wolf && newGoat== goat && newCabbage== cabbage - 1
t2: humanTravel && newWolf== wolf && newGoat== goat + 1 && newCabbage== cabbage
t5: humanTravel && newWolf== wolf && newGoat== goat - 1 && newCabbage== cabbage
t1: humanTravel && newWolf== wolf + 1 && newGoat== goat && newCabbage== cabbage
t4: humanTravel && newWolf== wolf - 1 && newGoat== goat && newCabbage== cabbage
safeAlone: newGoat != newWolf && newGoat != newCabbage
wolfSide: wolf== 0 || wolf== 1
humanTravel: human != newHuman
side: humanSide && wolfSide && goatSide && cabbageSide
safe: safeAlone || newGoat== newHuman
objectTravel: t1 || t2 || t3 || t4 || t5 || t6 || t7

fState:  And( And( And( human[Steps]  ==  1 , wolf[Steps]  ==  1 )  , goat[Steps]  ==  1 )  , cabbage[Steps]  ==  1 )  
final:  fState[Steps] 
fState:   
wolf:   
goat:   
cabbage:   
cabbageSide:  Or( cabbage[i]  ==  0 , cabbage[i]  ==  1 )  
goatSide:  Or( goat[i]  ==  0 , goat[i]  ==  1 )  
humanSide:  Or( human[i]  ==  0 , human[i]  ==  1 )  
t7:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage  ==  cabbage[i] )  
t3:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage  ==  cabbage[i] + 1 )  
t6:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage  ==  cabbage[i] - 1 )  
t2:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] )  , goat[i+1]  ==  goat[i] + 1 )  , cabbage  ==  cabbage[i] )  
t5:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] )  , goat[i+1]  ==  goat[i] - 1 )  , cabbage  ==  cabbage[i] )  
t1:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] + 1 )  , goat[i+1]  ==  goat[i] )  , cabbage  ==  cabbage[i] )  
t4:  And( And( And( humanTravel[i] , wolf  ==  wolf[i] - 1 )  , goat[i+1]  ==  goat[i] )  , cabbage  ==  cabbage[i] )  
safeAlone:  And( goat[i+1] != wolf , goat[i+1] != cabbage )  
wolfSide:  Or( wolf[i]  ==  0 , wolf[i]  ==  1 )  
humanTravel:  human[i] != human[i+1] 
side:  And( And( And( humanSide[i] , wolfSide[i] )  , goatSide[i] )  , cabbageSide[i] )  
safe:  Or( safeAlone[i] , goat[i+1]  ==  human[i+1] )  
objectTravel:  Or( Or( Or( Or( Or( Or( t1[i] , t2[i] )  , t3[i] )  , t4[i] )  , t5[i] )  , t6[i] )  , t7[i] )  
data:  And( And( And( side[i] , safe[i] )  , humanTravel[i] )  , objectTravel[i] )  

import json
from z3 import *
s = Solver()
Steps=7
Num= Steps+1
$code$
#template, only start rest
s.add(data + start)
#template
s.add(final)
ind = 0
f = open("/var/www/html/all/bin/python/log.txt", "a")
while s.check() == sat:
  ind = ind +1
  print ind
  m = s.model()
  print m
  print "traversing model..." 
  #for d in m.decls():
	#print "%s = %s" % (d.name(), m[d])
  f.write(str(m))
  f.write("\n\n")
  exit()
  #s.add(Or(goat[0] != s.model()[data[0]] )) # prevent next model from using the same assignment as a previous model
print "Total solution number: "
print ind  
f.close()

import json
from z3 import *
s = Solver()
Steps=7
Num= Steps+1
human = [ Int('human_%i' % (i + 1)) for i in range(Num) ]
wolf = [ Int('wolf_%i' % (i + 1)) for i in range(Num) ]
goat = [ Int('goat_%i' % (i + 1)) for i in range(Num) ]
cabbage = [ Int('cabbage_%i' % (i + 1)) for i in range(Num) ]
nothing= [  And( human[i] == human[i+1], wolf[i] == wolf[i+1], goat[i] == goat[i+1], cabbage[i] == cabbage[i+1] )   for i in range(Num-1) ]
start= [ human[0] == 1, wolf[0] == 0, goat[0] == 1, cabbage[0] == 0 ]
safeAlone= [  And( goat[i+1] != wolf[i+1] , goat[i+1] != cabbage[i+1] )   for i in range(Num-1) ]
safe= [  Or( safeAlone[i] , goat[i+1]  ==  human[i+1] )   for i in range(Num-1) ]
humanTravel= [  human[i] != human[i+1]  for i in range(Num-1) ]
cabbageSide= [  Or( cabbage[i]  ==  0 , cabbage[i]  ==  1 )   for i in range(Num-1) ]
goatSide= [  Or( goat[i]  ==  0 , goat[i]  ==  1 )   for i in range(Num-1) ]
humanSide= [  Or( human[i]  ==  0 , human[i]  ==  1 )   for i in range(Num-1) ]
t7= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage[i+1]  ==  cabbage[i] )   for i in range(Num-1) ]
t3= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage[i+1]  ==  cabbage[i] + 1 )   for i in range(Num-1) ]
t6= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] )  , goat[i+1]  ==  goat[i] )  , cabbage[i+1]  ==  cabbage[i] - 1 )   for i in range(Num-1) ]
t2= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] )  , goat[i+1]  ==  goat[i] + 1 )  , cabbage[i+1]  ==  cabbage[i] )   for i in range(Num-1) ]
t5= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] )  , goat[i+1]  ==  goat[i] - 1 )  , cabbage[i+1]  ==  cabbage[i] )   for i in range(Num-1) ]
t1= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] + 1 )  , goat[i+1]  ==  goat[i] )  , cabbage[i+1]  ==  cabbage[i] )   for i in range(Num-1) ]
t4= [  And( And( And( humanTravel[i] , wolf[i+1]  ==  wolf[i] - 1 )  , goat[i+1]  ==  goat[i] )  , cabbage[i+1]  ==  cabbage[i] )   for i in range(Num-1) ]
wolfSide= [  Or( wolf[i]  ==  0 , wolf[i]  ==  1 )   for i in range(Num-1) ]
side= [  And( And( And( humanSide[i] , wolfSide[i] )  , goatSide[i] )  , cabbageSide[i] )   for i in range(Num-1) ]
objectTravel= [  Or( Or( Or( Or( Or( Or( t1[i] , t2[i] )  , t3[i] )  , t4[i] )  , t5[i] )  , t6[i] )  , t7[i] )   for i in range(Num-1) ]
data= [ Or(  And( And( And( side[i] , safe[i] )  , humanTravel[i] )  , objectTravel[i] )   , nothing[i]) for i in range(Num-1) ]
fState=  And( And( And( human[Steps]  ==  1 , wolf[Steps]  ==  1 )  , goat[Steps]  ==  1 )  , cabbage[Steps]  ==  1 )  
final=  fState 
#template, only start rest
s.add(data + start)
#template
s.add(final)
ind = 0
f = open("/var/www/html/all/bin/python/log.txt", "a")
while s.check() == sat:
  ind = ind +1
  print ind
  m = s.model()
  print m
  print "traversing model..." 
  #for d in m.decls():
	#print "%s = %s" % (d.name(), m[d])
  f.write(str(m))
  f.write("\n\n")
  exit()
  #s.add(Or(goat[0] != s.model()[data[0]] )) # prevent next model from using the same assignment as a previous model
print "Total solution number: "
print ind  
f.close()

Winning transaction chain found:
Data transaction: human= 0, wolf= 0, goat= 1, cabbage= 0
Data transaction: human= 1, wolf= 0, goat= 1, cabbage= 1
Data transaction: human= 0, wolf= 0, goat= 0, cabbage= 1
Data transaction: human= 1, wolf= 1, goat= 0, cabbage= 1
Data transaction: human= 0, wolf= 1, goat= 0, cabbage= 1
Data transaction: human= 1, wolf= 1, goat= 1, cabbage= 1
Data transaction: human= 1, wolf= 1, goat= 1, cabbage= 1
Transfer transaction

let contract = tx.sender
let a= extract(getInteger(contract,"a"))
let b= extract(getInteger(contract,"b"))
let c= extract(getInteger(contract,"c"))
let d= extract(getInteger(contract,"d"))
match tx {
case t:DataTransaction =>
let na= extract(getInteger(t.data,"a")) 
let nb= extract(getInteger(t.data,"b"))
let nc= extract(getInteger(t.data,"c"))
let nd= extract(getInteger(t.data,"d"))
   nd == 0 || a == 100 - 5
case s:TransferTransaction =>
   ( a + b - c ) * d == 12
case _ => true
}