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{-# LANGUAGE GeneralizedNewtypeDeriving, MultiParamTypeClasses, EmptyDataDecls #-}
{- Copyright 2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Types.Cost where
import Utility.HumanTime
-- | An estimated cost to perform an operation.
data Cost op
= CPUCost Seconds -- ^ using 1 CPU core
deriving (Show, Eq, Ord)
unknownCost :: Cost op
unknownCost = CPUCost (Seconds 0)
newtype Seconds = Seconds Integer
deriving (Num, Eq, Ord)
instance Show Seconds where
show (Seconds n) = fromDuration (Duration n)
data UsingHardware = UsingCPU | UsingGPU | UsingASIC
deriving (Show)
instance Monoid (Cost t) where
mempty = CPUCost (Seconds 0)
CPUCost (Seconds a) `mappend` CPUCost (Seconds b) =
CPUCost (Seconds (a+b))
mapCost :: (Integer -> Integer) -> Cost op -> Cost op
mapCost f (CPUCost (Seconds n)) = CPUCost (Seconds (f n))
showCostMinutes :: Cost op -> String
showCostMinutes (CPUCost (Seconds n))
| n < 61 = "1 minute"
| otherwise = show (n `div` 60) ++ " minutes"
-- | Operations whose cost can be measured.
data DecryptionOp
data CreationOp
data BruteForceOp
-- | Things that track their creation cost.
class HasCreationCost t where
getCreationCost :: t -> Cost CreationOp
-- | Things that track their decryption cost.
class HasDecryptionCost t where
getDecryptionCost :: t -> Cost DecryptionOp
-- | Calculation of a cost that depends on some amount of entropy.
type CostCalc op t = Entropy t -> Cost op
unknownCostCalc :: CostCalc op t
unknownCostCalc = \_e -> error "No cost calculation available"
-- | Number of bits of entropy
newtype Entropy t = Entropy Int
deriving (Num, Show)
class CalcEntropy d t where
calcEntropy :: d -> Entropy t
-- | Entropy can never go negative when subtracting bits from it.
reduceEntropy :: Entropy t -> Int -> Entropy t
reduceEntropy (Entropy a) b = Entropy (max 0 (a - b))
-- | Things that can be brute-forced track their CostCalc.
class Bruteforceable t a where
getBruteCostCalc :: t -> CostCalc BruteForceOp a
-- | Things that can have entropy
data UnknownPassword
data UnknownName
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