DRBG-0.1.2: Crypto/Random/DRBG.hs
{-# LANGUAGE EmptyDataDecls, FlexibleInstances, TypeSynonymInstances, BangPatterns #-}
{-|
Maintainer: Thomas.DuBuisson@gmail.com
Stability: beta
Portability: portable
This module is the convenience interface for the DRBG (NIST standardized
number-theoretically secure random number generator). Everything is setup
for using the "crypto-api" 'CryptoRandomGen' type class. For example,
to seed a new generator with the system secure random ('System.Crypto.Random')
and generate some bytes (stepping the generator along the way) one would do:
@
gen <- newGenIO :: IO HashDRBG
let Right (randomBytes, newGen) = genBytes 1024 gen
@
Selecting the underlying hash algorithm is supporting using *DRBGWith types:
@
gen <- newGenIO :: IO (HmacDRBGWith SHA224)
@
Composition of generators is supported using two trivial compositions, 'GenXor'
and 'GenAutoReseed'. Additional compositions can be built by instanciating
a 'CryptoRandomGen' as desired.
@
gen <- newGenIO :: IO (GenBuffered (GenAutoReseed (GenXor AesCntDRBG (HashDRBGWith SHA384)) HmacDRBG))
@
-}
module Crypto.Random.DRBG
( HmacDRBG, HashDRBG
, HmacDRBGWith, HashDRBGWith
, GenXor
, GenAutoReseed
, GenBuffered
, module Crypto.Random
) where
import qualified Crypto.Random.DRBG.HMAC as M
import qualified Crypto.Random.DRBG.Hash as H
import Crypto.Classes
import Crypto.Random
import Crypto.Hash.SHA512 (SHA512)
import Crypto.Hash.SHA384 (SHA384)
import Crypto.Hash.SHA256 (SHA256)
import Crypto.Hash.SHA224 (SHA224)
import Crypto.Hash.SHA1 (SHA1)
import System.Crypto.Random
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
import Data.Tagged
import Data.Bits (xor)
import Control.Parallel
import Control.Monad (liftM)
import Control.Monad.Error () -- Either instance
import System.IO.Unsafe (unsafeInterleaveIO)
instance H.SeedLength SHA512 where
seedlen = Tagged 888
instance H.SeedLength SHA384 where
seedlen = Tagged 888
instance H.SeedLength SHA256 where
seedlen = Tagged 440
instance H.SeedLength SHA224 where
seedlen = Tagged 440
instance H.SeedLength SHA1 where
seedlen = Tagged 440
-- |The HMAC DRBG state (of kind * -> *) allowing selection
-- of the underlying hash algorithm (SHA1, SHA224 ... SHA512)
type HmacDRBGWith = M.State
-- |The Hash DRBG state (of kind * -> *) allowing selection
-- of the underlying hash algorithm.
type HashDRBGWith = H.State
-- |An alias for an HMAC DRBG generator using SHA512.
type HmacDRBG = M.State SHA512
-- |An Alias for a Hash DRBG generator using SHA512.
type HashDRBG = H.State SHA512
newGenAutoReseed :: (CryptoRandomGen a, CryptoRandomGen b) => B.ByteString -> Int -> Either GenError (GenAutoReseed a b)
newGenAutoReseed bs rsInterval=
let (b1,b2) = B.splitAt (genSeedLength `for` fromRight g1) bs
g1 = newGen b1
g2 = newGen b2
fromRight (Right x) = x
in case (g1, g2) of
(Right a, Right b) -> Right $ GenAutoReseed a b rsInterval 0
(Left e, _) -> Left e
(_, Left e) -> Left e
instance CryptoRandomGen HmacDRBG where
newGen bs =
let res = M.instantiate bs B.empty B.empty
in if B.length bs < genSeedLength `for` res
then Left NotEnoughEntropy
else Right res
genSeedLength = Tagged (512 `div` 8)
genBytes req g =
let res = M.generate g (req * 8) B.empty
in case res of
Nothing -> Left NeedReseed
Just (r,s) -> Right (r, s)
genBytesWithEntropy req ai g =
let res = M.generate g (req * 8) ai
in case res of
Nothing -> Left NeedReseed
Just (r,s) -> Right (r, s)
reseed ent g =
let res = M.reseed g ent B.empty
in if B.length ent < genSeedLength `for` res
then Left NotEnoughEntropy
else Right res
instance CryptoRandomGen HashDRBG where
newGen bs =
let res = H.instantiate bs B.empty B.empty
in if B.length bs < genSeedLength `for` res
then Left NotEnoughEntropy
else Right res
genSeedLength = Tagged $ 512 `div` 8
genBytes req g =
let res = H.generate g (req * 8) B.empty
in case res of
Nothing -> Left NeedReseed
Just (r,s) -> Right (r, s)
genBytesWithEntropy req ai g =
let res = H.generate g (req * 8) ai
in case res of
Nothing -> Left NeedReseed
Just (r,s) -> Right (r, s)
reseed ent g =
let res = H.reseed g ent B.empty
in if B.length ent < genSeedLength `for` res
then Left NotEnoughEntropy
else Right res
helper1 :: Tagged (GenAutoReseed a b) Int -> a
helper1 = const undefined
helper2 :: Tagged (GenAutoReseed a b) Int -> b
helper2 = const undefined
-- |@g :: GenAutoReseed a b@ is a generator of type a that gets
-- automatically reseeded by generator b upon every 32kB generated.
--
-- @reseed g ent@ will reseed both the component generators by
-- breaking ent up into two parts determined by the genSeedLength of each generator.
--
-- @genBytes@ will generate the requested bytes with generator @a@ and reseed @a@
-- using generator @b@ if there has been 32KB of generated data since the last reseed.
-- Note a request for > 32KB of data will be filled in one request to generator @a@ before
-- @a@ is reseeded by @b@.
--
-- @genBytesWithEntropy@ will push the entropy into generator @a@, leaving generator
-- @b@ unchanged unless the count hits 32KB, in which case it is reseeds @a@
-- (for a second time) using @b@ as in normal operation via @genBytes@.
data GenAutoReseed a b = GenAutoReseed !a !b !Int !Int
instance (CryptoRandomGen a, CryptoRandomGen b) => CryptoRandomGen (GenAutoReseed a b) where
{-# SPECIALIZE instance CryptoRandomGen (GenAutoReseed HmacDRBG HmacDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenAutoReseed HashDRBG HashDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenAutoReseed HashDRBG HmacDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenAutoReseed HmacDRBG HashDRBG) #-}
newGen bs = newGenAutoReseed bs (2^15)
genSeedLength =
let a = helper1 res
b = helper2 res
res = Tagged $ genSeedLength `for` a + genSeedLength `for` b
in res
genBytes req (GenAutoReseed a b rs cnt) = do
(res, aNew) <- genBytes req a
gNew <- if (cnt + req) > rs
then do (ent,b') <- genBytes (genSeedLength `for` a) b
a' <- reseed ent aNew
return (GenAutoReseed a' b' rs 0)
else return $ GenAutoReseed aNew b rs (cnt + req)
return (res, gNew)
genBytesWithEntropy req entropy (GenAutoReseed a b rs cnt) = do
(res, aNew) <- genBytesWithEntropy req entropy a
gNew <- if (cnt + req) > rs
then do (ent,b') <- genBytes (genSeedLength `for` a) b
a' <- reseed ent aNew
return (GenAutoReseed a' b' rs 0)
else return $ GenAutoReseed aNew b rs (cnt + req)
return (res, gNew)
reseed ent gen@(GenAutoReseed a b rs _)
| genSeedLength `for` gen > B.length ent = Left NotEnoughEntropy
| otherwise = do
let (e1,e2) = B.splitAt (genSeedLength `for` a) ent
a' <- reseed e1 a
b' <- if B.length e2 /= 0
then reseed e2 b
else return b
return $ GenAutoReseed a' b' rs 0
-- |@g :: GenXor a b@ generates bytes with sub-generators a and b
-- and exclusive-or's the outputs to produce the resulting bytes.
data GenXor a b = GenXor !a !b
helperXor1 :: Tagged (GenXor a b) c -> a
helperXor1 = const undefined
helperXor2 :: Tagged (GenXor a b) c -> b
helperXor2 = const undefined
instance (CryptoRandomGen a, CryptoRandomGen b) => CryptoRandomGen (GenXor a b) where
{-# SPECIALIZE instance CryptoRandomGen (GenXor HmacDRBG HmacDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenXor HashDRBG HmacDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenXor HmacDRBG HashDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenXor HashDRBG HashDRBG) #-}
newGen bs = do
let g1 = newGen b1
g2 = newGen b2
(b1,b2) = B.splitAt (genSeedLength `for` fromRight g1) bs
fromRight (Right x) = x
a <- g1
b <- g2
return (GenXor a b)
genSeedLength =
let a = helperXor1 res
b = helperXor2 res
res = Tagged $ (genSeedLength `for` a) + (genSeedLength `for` b)
in res
genBytes req (GenXor a b) = do
(r1, a') <- genBytes req a
(r2, b') <- genBytes req b
return (zwp' r1 r2, GenXor a' b')
genBytesWithEntropy req ent (GenXor a b) = do
(r1, a') <- genBytesWithEntropy req ent a
(r2, b') <- genBytesWithEntropy req ent b
return (zwp' r1 r2, GenXor a' b')
reseed ent (GenXor a b) = do
let (b1, b2) = B.splitAt (genSeedLength `for` a) ent
a' <- reseed b1 a
b' <- reseed b2 b
return (GenXor a' b')
-- |@g :: GenBuffered a@ is a generator of type @a@ that attempts to
-- maintain a buffer of random values size >= 1MB and <= 5MB at any time.
data GenBuffered g = GenBuffered Int Int (Either (GenError, g) (B.ByteString, g)) {-# UNPACK #-} !B.ByteString
proxyToGenBuffered :: Proxy g -> Proxy (Either GenError (GenBuffered g))
proxyToGenBuffered = const Proxy
bufferMinDef = 2^20
bufferMaxDef = 2^22
newGenBuffered :: (CryptoRandomGen g) => Int -> Int -> B.ByteString -> Either GenError (GenBuffered g)
newGenBuffered min max bs = do
g <- newGen bs
(rs,g') <- genBytes min g
let new = wrapErr (genBytes min g') g'
(let !_ = rs in ()) `par` return (GenBuffered min max new rs)
newGenBufferedIO :: CryptoRandomGen g => Int -> Int -> IO (GenBuffered g)
newGenBufferedIO min max = do
g <- newGenIO
let !(Right !gBuf) = do
(rs,g') <- genBytes min g
let new = wrapErr (genBytes min g') g'
(let !_ = rs in ()) `par` return (GenBuffered min max new rs)
return gBuf
instance (CryptoRandomGen g) => CryptoRandomGen (GenBuffered g) where
{-# SPECIALIZE instance CryptoRandomGen (GenBuffered HmacDRBG) #-}
{-# SPECIALIZE instance CryptoRandomGen (GenBuffered HashDRBG) #-}
newGen = newGenBuffered bufferMinDef bufferMaxDef
newGenIO = newGenBufferedIO bufferMinDef bufferMaxDef
genSeedLength =
let a = help res
res = Tagged $ genSeedLength `for` a
in res
where
help :: Tagged (GenBuffered g) c -> g
help = const undefined
genBytes req gb@(GenBuffered min max g bs)
| remSize >= min = Right (B.take req bs, GenBuffered min max g (B.drop req bs))
| B.length bs < min =
case g of
Left (err,_) -> Left err
Right g -> Left (GenErrorOther "Buffering generator failed to buffer properly - unknown reason")
| req > B.length bs = Left RequestedTooManyBytes
| remSize < min =
case g of
Left (err,_) -> Left err
Right (rnd, gen) ->
let new | B.length rnd > 0 = wrapErr (genBytes (max - (remSize + B.length rnd)) gen) gen
| otherwise = Right (B.empty,gen)
(rs,rem) = B.splitAt req bs
in (eval new) `par` Right (rs, GenBuffered min max new (B.append rem rnd))
| otherwise = Left $ GenErrorOther "Buffering generator hit an impossible case. Please inform the Haskell crypto-api maintainer"
where
remSize = B.length bs - req
genBytesWithEntropy req ent g = reseed ent g >>= \gen -> genBytes req gen
reseed ent (GenBuffered min max g bs) = do
let (rs, g') =
case g of
Left (_,g') -> (B.empty, g')
Right (rs, g') -> (rs, g')
g'' <- reseed ent g'
let new = wrapErr (genBytes (min-B.length bs') g'') g''
bs' = B.take max (B.append bs rs)
return (GenBuffered min max new bs')
wrapErr :: Either x y -> g -> Either (x,g) y
wrapErr (Left x) g = Left (x,g)
wrapErr (Right r) _ = Right r
-- |Force evaluation for use by GenBuffered.
eval :: Either x (B.ByteString, g) -> Either x (B.ByteString, g)
eval (Left x) = Left x
eval (Right (g,bs)) = bs `seq` (g `seq` (Right (g, bs)))
-- |zipWith xor + Pack
-- As a result of rewrite rules, this should automatically be optimized (at compile time)
-- to use the bytestring libraries 'zipWith'' function.
zwp' a = B.pack . B.zipWith xor a