cryptopals

commit 706563d1fa30a3bd75f94e6987b90860f8fa522a
parent 28d78912500b58309199ad07aa216081a23e97c7
Author: Jared Tobin <jared@jtobin.io>
Date:   Sun, 30 Jul 2023 12:02:55 -0230

Add 3.22.

Diffstat:
M
cryptopals.cabal
 | 
11
+++++++++++
M
docs/s3.md
 | 
43
+++++++++++++++++++++++++++++++++++++++++++
A
etc/crackmt.sh
 | 
14
++++++++++++++
A
src/MT19937.hs
 | 
40
++++++++++++++++++++++++++++++++++++++++

4 files changed, 108 insertions(+), 0 deletions(-)
diff --git a/cryptopals.cabal b/cryptopals.cabal
@@ -159,3 +159,14 @@ executable pkcs7
     , optparse-applicative
     , text
 
+executable mt19937
+  main-is:           MT19937.hs
+  ghc-options:       -Wall -O2
+  default-language:  Haskell2010
+  hs-source-dirs:    src
+  build-depends:
+      base
+    , cryptopals
+    , optparse-applicative
+    , text
+
diff --git a/docs/s3.md b/docs/s3.md
@@ -122,3 +122,46 @@ the implementations he cites return signed 32-bit integers, but I
 use (unsigned) Word32. One can convert results to e.g. Int32 with
 fromIntegral to verify.
 
+There's also a binary:
+
+    $ mt19937 42 3
+    1608637542
+    3421126067
+    4083286876
+
+#### 3.22
+
+After the fourth or fifth time my children woke me up in the middle of
+the night, I decided to just get up and pick at this stuff. I kicked off
+this business somewhere around 5-6am:
+
+    $ sleep $(shuf -i 40-1000 -n 1); ts=$(date +%s); \
+      sleep $(shuf -i 40-1000 -n 1); mt19937 $ts 1
+    1133750118
+
+and then lay down again and fell asleep for a few hours. Using [this
+timestamp calculator](https://www.unixtimestamp.com/) after the fact,
+the timestamp is probably somewhere in the range of about \[1690702400,
+1690708000\].  So, using:
+
+    #!/usr/bin/env bash
+    declare -i i
+    i=1690702400
+    while (($i < 1690708000)); do
+      val=$(mt19937 $i 1)
+      if (($val == 1133750118)); then
+        echo "seed is $i"
+        exit
+      else
+        i+=1
+      fi
+    done
+
+we get:
+
+    $ ./crackmt.sh
+    seed is 1690706100
+
+So, via the same timestamp calculator, it was seeded at Sun Jul 30 2023
+06:05:00 GMT-0230 (heure d’été de Terre-Neuve).
+
diff --git a/etc/crackmt.sh b/etc/crackmt.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+declare -i i
+i=1690702400
+while (($i < 1690708000)); do
+  val=$(mt19937 $i 1)
+  echo "seed: $i, val: $val"
+  if (($val == 1133750118)); then
+    echo "seed is $i"
+    exit
+  else
+    i+=1
+  fi
+done
+
diff --git a/src/MT19937.hs b/src/MT19937.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+
+module Main where
+
+import qualified Cryptopals.Stream.RNG.MT19937 as MT
+import qualified Data.Text as T
+import qualified Data.Text.IO as TIO
+import Data.Foldable (for_)
+import GHC.Word (Word32)
+import qualified Options.Applicative as O
+
+data Args = Args {
+    argsSeed  :: Word32
+  , argsBytes :: Word32
+  }
+
+ops :: O.Parser Args
+ops = Args
+  <$> O.argument O.auto (O.metavar "SEED")
+  <*> O.argument O.auto (O.metavar "BYTES")
+
+mt :: Args -> IO ()
+mt Args {..} = do
+  let gen        = MT.seed argsSeed
+      (bytes, _) = MT.bytes (fromIntegral argsBytes) gen
+
+  for_ bytes $ TIO.putStrLn . T.pack . show
+
+main :: IO ()
+main = do
+  let pars = O.info (O.helper <*> ops) $
+           O.fullDesc
+        <> O.progDesc "generate random bytes from a Mersenne Twister"
+        <> O.header "mt19937"
+
+  args <- O.execParser pars
+
+  mt args
+