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{-# LANGUAGE GeneralizedNewtypeDeriving, MultiParamTypeClasses #-}
{- Copyright 2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Cost (
module Cost,
module Types.Cost
) where
import Types.Cost
-- | Cost in seconds, with the type of hardware needed.
totalCost :: Cost op -> (Seconds, [UsingHardware])
totalCost (CPUCost s) = (s, [UsingCPU])
raiseCostPower :: Cost c -> Entropy e -> Cost c
raiseCostPower c (Entropy e) = adjustCost c (* 2^e)
adjustCost :: Cost c -> (Seconds -> Seconds) -> Cost c
adjustCost (CPUCost s) f = CPUCost (f s)
castCost :: Cost a -> Cost b
castCost (CPUCost s) = CPUCost s
-- | CostCalc for a brute force linear search through an entropy space
-- in which each step entails paying a cost.
--
-- On average, the solution will be found half way through.
-- This is equivilant to one bit less of entropy.
bruteForceLinearSearch :: Cost step -> CostCalc BruteForceOp t
bruteForceLinearSearch stepcost e =
castCost stepcost `raiseCostPower` reduceEntropy e 1
-- | Estimate of cost of a brute force attack.
estimateBruteforceOf :: Bruteforceable t a => t -> Entropy a -> Cost BruteForceOp
estimateBruteforceOf t e = getBruteCostCalc t e
data DataCenterPrice = DataCenterPrice
{ instanceCpuCores :: Integer
, instanceCostPerHour :: Cents
}
-- August 2016 spot pricing: 36 CPU core c4.8xlarge at 33c/hour
spotAWS :: DataCenterPrice
spotAWS = DataCenterPrice
{ instanceCpuCores = 36
, instanceCostPerHour = Cents 33
}
-- | Estimate of cost of brute force attack using a datacenter.
--
-- Note that this assumes that CPU cores and GPU cores are of equal number,
-- which is unlikely to be the case; typically there will be many more
-- cores than GPUs. So, this underestimates the price to brute force
-- operations which run faster on GPUs.
estimateAttackCost :: DataCenterPrice -> Cost BruteForceOp -> Dollars
estimateAttackCost dc opcost = centsToDollars $ costcents
where
(Seconds cpuseconds) = fst (totalCost opcost)
cpuyears = cpuseconds `div` (60*60*24*365)
costpercpuyear = Cents $
fromIntegral (instanceCostPerHour dc) * 24 * 365
`div` instanceCpuCores dc
costcents = Cents cpuyears * costpercpuyear
newtype Cents = Cents Integer
deriving (Num, Integral, Enum, Real, Ord, Eq, Show)
newtype Dollars = Dollars Integer
deriving (Num, Integral, Enum, Real, Ord, Eq)
instance Show Dollars where
show (Dollars n) = go
[ (1000000000000, "trillion")
, (1000000000, "billion")
, (1000000, "million")
, (1000, "thousand")
]
where
go [] = "$" ++ show n
go ((d, u):us)
| n >= d =
let n' = n `div` d
in "$" ++ show n' ++ " " ++ u
| otherwise = go us
centsToDollars :: Cents -> Dollars
centsToDollars (Cents c) = Dollars (c `div` 100)
type Year = Integer
-- | Apply Moore's law to show how a cost might vary over time.
costOverTime :: Dollars -> Year -> [(Dollars, Year)]
costOverTime (Dollars currcost) thisyear =
(Dollars currcost, thisyear) : map calc otheryears
where
otheryears = [thisyear+1, thisyear+5, thisyear+10]
calc y =
let monthdelta = (fromIntegral ((y * 12) - (thisyear * 12))) :: Double
cost = floor $ fromIntegral currcost / 2 ** (monthdelta / 18)
in (Dollars cost, y)
costOverTimeTable :: Dollars -> Year -> [String]
costOverTimeTable cost thisyear = go [] thisyear $ costOverTime cost thisyear
where
go t _ [] = reverse t
go t yprev ((c, y):ys) =
let s = " in " ++ show y ++ ": " ++ show c
in if yprev < y - 1
then go (s:" ...":t) y ys
else go (s:t) y ys
|
