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Diffstat (limited to 'Cost.hs')
| -rw-r--r-- | Cost.hs | 150 |
1 files changed, 150 insertions, 0 deletions
@@ -0,0 +1,150 @@ +{-# 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 +import Data.List +import Data.Maybe +import Text.Read + +-- | 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) = mapCost (* 2^e) c + +mapCost :: (Rational-> Rational) -> Cost op -> Cost op +mapCost f (CPUCost (Seconds n) d) = CPUCost (Seconds (f n)) d + +type NumCores = Integer + +showCostMinutes :: NumCores -> Cost op -> String +showCostMinutes numcores (CPUCost (Seconds n) (Divisibility d)) + | n' < 61 = "1 minute" + | otherwise = show (n' / 60) ++ " minutes" + where + n' :: Double + n' = fromRational n / fromIntegral (min numcores d) + +-- If an operation took n seconds on a number of cores, +-- multiply to get the CPUCost, which is for a single core. +coreCost :: NumCores -> Seconds -> Divisibility -> Cost op +coreCost cores (Seconds n) d = CPUCost (Seconds (fromIntegral cores * n)) d + +castCost :: Cost a -> Cost b +castCost (CPUCost s d) = CPUCost s d + +-- | 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 + , instanceCpuCoreMultiplier :: Integer + -- ^ If the cores are twice as fast as the commodity hardware + -- that keysafe's cost estimates are based on, use 2 to indicate + -- this, etc. + , instanceCostPerHour :: Cents + } + +-- August 2016 spot pricing: 36 CPU core c4.8xlarge at 33c/hour +spotAWS :: DataCenterPrice +spotAWS = DataCenterPrice + { instanceCpuCores = 36 + , instanceCpuCoreMultiplier = 2 + , 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 / (60*60*24*365) + costpercpuyear = Cents $ + fromIntegral (instanceCostPerHour dc) * 24 * 365 + `div` (instanceCpuCores dc * instanceCpuCoreMultiplier dc) + costcents = Cents (ceiling 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 + +-- Number of physical cores. This is not the same as +-- getNumProcessors, which includes hyper-threading. +getNumCores :: IO (Maybe NumCores) +getNumCores = getmax . mapMaybe parse . lines <$> readFile "/proc/cpuinfo" + where + getmax [] = Nothing + getmax l = Just $ + maximum l + 1 -- add 1 because /proc/cpuinfo counts from 0 + parse l + | "core id" `isPrefixOf` l = + readMaybe $ drop 1 $ dropWhile (/= ':') l + | otherwise = Nothing |