dice-entropy-conduit (empty) → 1.0.0.0
raw patch · 6 files changed
+785/−0 lines, 6 filesdep +QuickCheckdep +basedep +bytestringsetup-changed
Dependencies added: QuickCheck, base, bytestring, conduit, entropy, test-framework, test-framework-quickcheck2, transformers
Files
- LICENSE +508/−0
- Setup.hs +2/−0
- dice-entropy-conduit.cabal +48/−0
- src/System/Random/Dice.hs +51/−0
- src/System/Random/Dice/Internal.hs +147/−0
- tests/Tests.hs +29/−0
+ LICENSE view
@@ -0,0 +1,508 @@+Copyright 2008-2009, Peter Robinson <thaldyron@gmail.com>. All rights reserved.++ GNU LESSER GENERAL PUBLIC LICENSE+ Version 2.1, February 1999++ Copyright (C) 1991, 1999 Free Software Foundation, Inc.+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA+ Everyone is permitted to copy and distribute verbatim copies+ of this license document, but changing it is not allowed.++[This is the first released version of the Lesser GPL. It also counts+ as the successor of the GNU Library Public License, version 2, hence+ the version number 2.1.]++ Preamble++ The licenses for most software are designed to take away your+freedom to share and change it. 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+ Setup.hs view
@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain
+ dice-entropy-conduit.cabal view
@@ -0,0 +1,48 @@+name: dice-entropy-conduit+version: 1.0.0.0+cabal-version: >=1.8+build-type: Simple+license: LGPL-2.1+license-file: LICENSE+author: Peter Robinson <peter.robinson@monoid.at>+maintainer: peter.robinson@monoid.at+copyright: Peter Robinson 2014+homepage: http://monoid.at/code+tested-with: GHC==7.8.3+stability: experimental+category: Cryptography, Data +synopsis: Cryptographically secure n-sided dice via rejection sampling. +description: + This library uses rejection sampling to provide cryptographically secure + @n@-sided dice rolls and random sampling (within a given range). + The number of used random bits is close to the information-theoretic optimal+ bound.+ .+ The API provides a conduit interface.+ See module "System.Random.Dice" for a more detailed description.+ .+ Feedback is welcome!++library+ hs-source-dirs: src+ build-depends: base == 4.*+ ,bytestring >= 0.9+ ,entropy >= 0.3.2+ ,conduit >= 1.1.7+ ,transformers >= 0.4.0.0++ ghc-options: -Wall + exposed-modules: System.Random.Dice+ System.Random.Dice.Internal+++test-suite Main+ type: exitcode-stdio-1.0+ x-uses-tf: true+ build-depends: base >= 4 && < 5,+ QuickCheck >= 2.4,+ test-framework >= 0.4.1,+ test-framework-quickcheck2+ hs-source-dirs: src, tests+ main-is: Tests.hs+
+ src/System/Random/Dice.hs view
@@ -0,0 +1,51 @@+{-# LANGUAGE Rank2Types #-}+-----------------------------------------------------------------------------+-- |+-- Module : System.Random.Dice+-- Copyright : Peter Robinson 2014+-- License : LGPL+-- +-- Maintainer : Peter Robinson <peter.robinson@monoid.at>+-- Stability : experimental+-- Portability : portable+--+-- This module implements an @n@-sided dice and provides sampling from a given+-- integer range.+-- The algorithm uses rejection sampling and attempts to keep the total number+-- of used random bits as close as possible to the information theoretic lower+-- bound of @ln(n) / ln(2)@ (for a range of size @n@).+-- +-- The implementation exposes streams of random values as conduits, see+-- 'diceRolls' and 'randomRs'. We also provide IO wrappers around these+-- functions, see 'getDiceRolls' and 'getRandomRs'.+-- The conduit interface allows us to use a specific entropy source, which has+-- type 'Producer' 'IO' 'Word'. +--+-- /Usage:/+-- +-- If we wanted to use the system-specific entropy source ('systemEntropy') to+-- produce 10 dice rolls of a 6-sided dice (i.e. range [0,5]), we could write:+--+-- > > systemEntropy $$ diceRolls 6 =$= CL.take 10 +-- > [5,1,3,3,0,5,3,2,2,1]+--+-- The function 'testPerformance' yields the actual number of consumed random+-- bits:+-- +-- > > testPerformance 12 10000+-- > Generated 10000 random samples in range [0,11]+-- > Average number of bits used: 3.5904+-- > Entropy lower bound on the number of required bits: 3.5849625007211565+-- > Performance ratio: 1.0015167520658164+--+-----------------------------------------------------------------------------+module System.Random.Dice( diceRolls+ , randomRs+ , getDiceRolls+ , getRandomRs+ , testPerformance+ , systemEntropy+ )+where+import System.Random.Dice.Internal+
+ src/System/Random/Dice/Internal.hs view
@@ -0,0 +1,147 @@+{-# LANGUAGE Rank2Types, DataKinds #-}+-----------------------------------------------------------------------------+-- |+-- Module : System.Random.Dice.Internal+-- Copyright : Peter Robinson 2014+-- License : LGPL+-- +-- Maintainer : Peter Robinson <peter.robinson@monoid.at>+-- Stability : experimental+-- Portability : portable+--+-----------------------------------------------------------------------------+module System.Random.Dice.Internal+where+import System.Entropy+import Control.Monad.IO.Class+import Control.Monad+import Control.Exception+import qualified Data.ByteString as B+import Data.Word+import Data.Conduit+import qualified Data.Conduit.List as CL++-- | Converts a number to its base-2 representation (as a list of bits) +-- and prepends zeros to ensure the minimal size.+integralToBits :: (Integral n,Integral m)+ => Int -- ^ minimal number of bits @b@+ -> n -- ^ the number @n@+ -> [m] -- ^ bit representation of @n@, length >= @b@+integralToBits b x = reverse $ integralToBits' 0 x + where+ integralToBits' ns 0 = replicate (b-ns) 0+ integralToBits' ns y = + let (a,res) = quotRem y 2 in + fromIntegral res : integralToBits' (ns+1) a+ ++-- | Convert a list of bits to an integral+bitsToIntegral :: (Integral n) =>[n] -> n+bitsToIntegral = extendIntegralWithBits 0 + ++extendIntegralWithBits :: (Integral n) => n -> [n] -> n+extendIntegralWithBits n = foldr (\c r -> 2*r + c) n . reverse+++-- | Upper bound on the number of sides that a random dice can have.+upperBound :: Word64+upperBound = 2^(55 :: Int)+++-- | Generates @k@ rolls of an @n@ sided dice.+getDiceRolls :: Int -- ^ @n:@ number of sides+ -> Int -- ^ @k:@ number of rolls+ -> IO [Int]+getDiceRolls n len = + systemEntropy $$ diceRolls n =$= CL.take len +++-- | Generates a list of random integer values in the specified range.+getRandomRs :: (Int,Int) -- ^ (inclusive) range+ -> Int -- ^ number of samples+ -> IO [Int]+getRandomRs range len = + systemEntropy $$ randomRs range =$= CL.take len+++-- | Produces a stream of random integer values in the range @[0,n-1]@, for a+-- given @n <= 2^55@.+-- This conduit needs to be attached to an entropy source such as+-- 'systemEntropy'.+diceRolls :: Int -> Conduit Word8 IO Int+diceRolls n+ | fromIntegral n > upperBound || n <= 0+ = throw $ AssertionFailed "diceRolls: n-sided dice are supported, for 1 <= n < 2^55."+ | n == 1 + = CL.sourceList [0,0..] + | otherwise + = dRoll (fromIntegral n) 1 0 =$= CL.map fst+++-- | Produces a stream of random integer values within a range.+-- This conduit needs to be attached to an entropy source such as+-- 'systemEntropy'.+randomRs :: (Int,Int) -- ^ range (inclusive)+ -> Conduit Word8 IO Int+randomRs (low,up) = diceRolls (up-low+1) =$= CL.map (+low)+++-- | A source of entropy. By default, we use the 'getEntropy' function from+-- the entropy package, see 'systemEntropy'. +--+-- /Warning:/ When combining a source of entropy with another conduits, it is+-- important to ensure that there is no \"backflow\" due to leftover values that +-- are being returned to the+-- source from the conduit. This can be done by fusing the conduit with the+-- identity map, e.g: @myEntropySrc $$ Data.Conduit.List.map id =$= myConduit@+-- +systemEntropy :: Producer IO Word8 +systemEntropy = do+ bytes <- B.unpack `liftM` liftIO (getEntropy 8)+ forM_ bytes yield+ systemEntropy ++++-- | Internal function. Should not be invoked directly. +dRoll :: Word64 -> Word64 -> Word64 -> Conduit Word8 IO (Int,Int)+dRoll n m r = do+-- | num > len = print ("end:",num,m,r) >> return []+-- | otherwise = do+ let k = ceiling $ (logBase 2 (fromIntegral upperBound) - logBase 2 (fromIntegral m :: Double)) / 8 + let m' = 2^(8*k) * m+ bits <- (concatMap (integralToBits 8) . B.unpack) + `liftM` (if k>0 then liftIO $ getEntropy k else return $ B.pack [])+ let w64 = extendIntegralWithBits r bits+ let q = m' `div` n+ if w64 < n * q + then do+ yield (fromIntegral $ w64 `mod` n,k)+ dRoll n q (w64 `div` n)+ else dRoll n (m' - n*q) (w64 - n*q)+++-- | Compute the performance of the algorithm in terms of used random bits+-- versus produced random values.+testPerformance :: Int -- ^ number of sides of dice+ -> Int -- ^ number of samples used for computing average.+ -> IO ()+testPerformance n len + | fromIntegral n > upperBound+ = throw $ AssertionFailed "dice: range must be within Word64 bounds."+ | otherwise = do+ nbits <- systemEntropy $= dRoll (fromIntegral n) 1 0 + $$ CL.take len + >>= return . sum . map snd+ putStrLn $ "Generated " ++ show len + ++ " random samples in range [0," ++ show (n-1) ++ "]"+ putStrLn $ "Average number of bits used: " + ++ show (8*fromIntegral nbits/ fromIntegral len :: Double)+ let lbound = logBase 2 (fromIntegral n) :: Double+ putStrLn $ "Entropy lower bound on the number of required bits: " + ++ show lbound+ putStrLn $ "Performance ratio: " ++ show (((8*fromIntegral nbits + / fromIntegral len) ::Double) / lbound)++
+ tests/Tests.hs view
@@ -0,0 +1,29 @@+module Main+where+import Data.Monoid+import Test.Framework+import Test.Framework.Providers.QuickCheck2+import Test.QuickCheck+import Data.Maybe+import qualified Data.List as L+import Control.Monad++import Data.ByteString.Lazy( ByteString )+import qualified Data.ByteString.Lazy as B++import System.Random.Dice.Internal++instance Arbitrary ByteString where+ arbitrary = fmap B.pack arbitrary++main :: IO ()+main = defaultMainWithOpts+ [ testProperty "convertingToFromBits" propConvertingToFromBits+ ] mempty++propConvertingToFromBits bstr = + let ws = B.unpack bstr in+ let ws' = map (integralToBits 8) ws in+ ws == map bitsToIntegral ws'+ +