From 13c408d2295597540f0b2dfb6f7b86e739876c90 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Mon, 12 Sep 2016 22:35:47 -0400
Subject: implement client-server Proof Of Work

Mashed up a argon2-based PoW with token buckets and bloom filters.
This is intended to prevent a few abuses including:

* Using a keysafe server for general file storage, by storing a whole
  lot of chunks.
* An attacker guessing names that people will use, and uploading junk
  to keysafe servers under those names, to make it harder for others to use
  keysafe later.
* An attacker trying to guess the names used for objects on keysafe
  servers in order to download them and start password cracking.
  (As a second level of defense, since the name generation hash
  is expensive already.)

Completely untested, but it builds!

This commit was sponsored by Andreas on Patreon.
---
 ExpensiveHash.hs | 61 --------------------------------------------------------
 1 file changed, 61 deletions(-)

(limited to 'ExpensiveHash.hs')

diff --git a/ExpensiveHash.hs b/ExpensiveHash.hs
index b46b23c..6fab15c 100644
--- a/ExpensiveHash.hs
+++ b/ExpensiveHash.hs
@@ -7,20 +7,14 @@
 
 module ExpensiveHash where
 
-import Types
 import Tunables
 import Cost
 import Serialization ()
 import qualified Data.Text as T
 import qualified Data.ByteString as B
-import qualified Data.ByteString.UTF8 as BU8
 import qualified Crypto.Argon2 as Argon2
 import Raaz.Core.Encode
-import Data.Time.Clock
-import Control.DeepSeq
-import Control.Monad
 import Data.Monoid
-import Data.Maybe
 
 -- | A hash that is expensive to calculate.
 --
@@ -46,58 +40,3 @@ expensiveHash (UseArgon2 cost opts) (Salt s) b = ExpensiveHash cost $
 	argonsalt = 
 		let sb = toByteString s
 		in sb <> B.replicate (8 - B.length sb ) 32
-
-benchmarkExpensiveHash :: Int -> ExpensiveHashTunable -> Cost op -> IO (BenchmarkResult (Cost op))
-benchmarkExpensiveHash rounds tunables@(UseArgon2 _ hashopts) expected = do
-	numcores <- fromIntegral . fromMaybe (error "Unknown number of physical cores.") 
-		<$> getNumCores
-	start <- getCurrentTime
-	forM_ [1..rounds] $ \n -> do
-		-- Must vary the data being hashed to avoid laziness
-		-- caching hash results.
-		let base = BU8.fromString (show n)
-		let ExpensiveHash _ t = expensiveHash tunables
-			(Salt (GpgKey (KeyId (base <> "dummy"))))
-			(base <> "himom")
-		t `deepseq` return ()
-	end <- getCurrentTime
-	let diff = floor $ end `diffUTCTime` start
-	let maxthreads = Argon2.hashParallelism hashopts
-	let actual = CPUCost (Seconds diff) (Divisibility $ fromIntegral maxthreads)
-	-- The expected cost is for a single core, so adjust it
-	-- based on the number of cores, up to a maximum of the number
-	-- of threads that the hash is configred to use.
-	let usedcores = min maxthreads numcores
-	let adjustedexpected = mapCost (`div` fromIntegral usedcores) expected
-	return $ BenchmarkResult
-		{ expectedBenchmark = adjustedexpected
-		, actualBenchmark = actual
-		}
-
-benchmarkTunables :: Tunables -> IO ()
-benchmarkTunables tunables = do
-	putStrLn "/proc/cpuinfo:"
-	putStrLn =<< readFile "/proc/cpuinfo"
-	
-	-- Rather than run all 256 rounds of this hash, which would
-	-- probably take on the order of 1 hour, run only 16, and scale
-	-- the expected cost accordingly.
-	let normalrounds = fromIntegral $ 
-		256 * randomSaltBytes (keyEncryptionKeyTunable tunables)
-	putStrLn $ "Benchmarking 16/" ++ show normalrounds ++ " rounds of key encryption key hash..."
-	r <- benchmarkExpensiveHash 16
-		(keyEncryptionKeyHash $ keyEncryptionKeyTunable tunables)
-		(mapCost (`div` (normalrounds `div` 16)) $ randomSaltBytesBruteForceCost $ keyEncryptionKeyTunable tunables)
-	print r
-	putStrLn $ "Estimated time for " ++ show normalrounds ++ " rounds of key encryption key hash..."
-	print $ BenchmarkResult
-		{ expectedBenchmark = mapCost (* 16) (expectedBenchmark r)
-		, actualBenchmark = mapCost (* 16) (actualBenchmark r)
-		}
-
-	putStrLn "Benchmarking 1 round of name generation hash..."
-	print =<< benchmarkExpensiveHash 1
-		(nameGenerationHash $ nameGenerationTunable tunables)
-		(getexpected $ nameGenerationHash $ nameGenerationTunable tunables)
-  where
-	getexpected (UseArgon2 cost _) = cost
-- 
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