aws spot instance attack cost estimate

1 files changed, 32 insertions, 1 deletions

diff --git a/Cost.hs b/Cost.hs
index 99baa33..de5a82d 100644
--- a/Cost.hs
+++ b/Cost.hs
@@ -6,7 +6,10 @@ import Utility.HumanTime
 import Data.Monoid
 
 -- | An estimated cost to perform an operation.
-data Cost op = CPUCost Seconds | GPUCost Seconds | CombinedCost (Cost op) (Cost op)
+data Cost op 
+	= CPUCost Seconds
+	| GPUCost Seconds
+	| CombinedCost (Cost op) (Cost op)
 	deriving (Show)
 
 newtype Seconds = Seconds Integer
@@ -80,5 +83,33 @@ bruteForceLinearSearch stepcost e =
 class Bruteforceable t a where
 	getBruteCostCalc :: t -> CostCalc BruteForceOp a
 
+-- | Estimate of cost of a brute force attack.
 estimateBruteforceOf :: Bruteforceable t a => t -> Entropy a -> Cost BruteForceOp
 estimateBruteforceOf t e = getBruteCostCalc t e
+
+-- | Estimate of cost of brute force attack using AWS Spot instances,
+-- in US dollars.
+--
+-- August 2016 spot pricing: 36 CPU core c4.8xlarge at 33c/hour
+--
+-- Note that less GPU time is available on these instances;
+-- there are not 36 GPU cores. But for simplicity we assume there are
+-- that many GPU cores. So, this underestimates the price to brute
+-- force such operations.
+estimateAWSSpotAttack :: Cost BruteForceOp -> Dollars
+estimateAWSSpotAttack opcost = centsToDollars $ costcents
+  where
+	(Seconds cpuseconds) = fst (totalCost opcost)
+	cpuyears = cpuseconds `div` (60*60*24*365)
+	cpucores = 36
+	costpercpuyear = Cents (33*24*365 `div` cpucores)
+	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, Show)
+
+centsToDollars :: Cents -> Dollars
+centsToDollars (Cents c) = Dollars (c `div` 100)