Added more comprehensive tutorial

Crypto/Tutorial.hs

@@ -1,34 +1,57 @@
-{-# OPTIONS_GHC -fno-warn-unused-imports #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE GADTs #-}
 
-{-| How to use @cryptonite@
+{- How to use @cryptonite@ with symmetric block ciphers
 
-> -- | Beware MUST BE 256bits as we use AES256
-> import Data.ByteString (ByteString)
-> import Crypto.Cipher.AES (AES256)
-> import Crypto.Cipher.Types (BlockCipher(..), Cipher(..),nullIV)
-> import Crypto.Error (CryptoFailable(..))
->
-> secretKey :: ByteString
-> secretKey = "012-456-89A-CDE-012-456-89A-CDE-"
->
-> encrypt :: ByteString -> ByteString -> ByteString
-> encrypt secret = ctrCombine ctx nullIV
->   where
->     ctx = cipherInitNoErr (cipherMakeKey (undefined :: AES256) secret)
->     cipherInitNoErr :: BlockCipher c => Key c -> c
->     cipherInitNoErr (Key k) = case cipherInit k of
->       CryptoPassed a -> a
->       CryptoFailed e -> error (show e)
->     cipherMakeKey :: Cipher cipher => cipher -> ByteString -> Key cipher
->     cipherMakeKey _ = Key -- Yeah Lazyness!!!!!!
->
->
-> decrypt :: ByteString -> ByteString -> ByteString
+> import           Crypto.Cipher.AES (AES256)
+> import           Crypto.Cipher.Types (BlockCipher(..), Cipher(..), nullIV, KeySizeSpecifier(..))
+> import           Crypto.Error (CryptoFailable(..), CryptoError(..))
+> 
+> import qualified Crypto.Random.Types as CRT
+> 
+> import           Data.ByteArray (ByteArray)
+> import           Data.ByteString (ByteString)
+> 
+> -- | Not required, but most general implementation
+> data Key c a where
+>   Key :: (BlockCipher c, ByteArray a) => a -> Key c a 
+> 
+> genPrivateKey :: forall m c a. (CRT.MonadRandom m, BlockCipher c, ByteArray a) 
+>               => c -> m (Key c a) 
+> genPrivateKey _ = fmap Key $ CRT.getRandomBytes $
+>   case cipherKeySize (undefined :: c) of
+>     KeySizeRange _ maxSize -> maxSize 
+>     KeySizeFixed ks -> ks 
+>     KeySizeEnum [] -> error "No key size specified"
+>     KeySizeEnum kss -> last kss -- largest key size
+>     
+> initCipher :: (BlockCipher c, ByteArray a) => Key c a -> Either CryptoError c
+> initCipher (Key k) = case cipherInit k of
+>   CryptoFailed e -> Left e
+>   CryptoPassed a -> Right a
+> 
+> encrypt :: (BlockCipher c, ByteArray a) => Key c a -> a -> Either CryptoError a
+> encrypt privKey msg = 
+>   case initCipher privKey of
+>     Left e -> Left e
+>     Right c -> Right $ ctrCombine c nullIV msg
+>     
+> decrypt :: (BlockCipher c, ByteArray a) => Key c a -> a -> Either CryptoError a 
 > decrypt = encrypt
+> 
+> exampleAES256 :: ByteString -> IO ()
+> exampleAES256 msg = do
+>   privKey <- genPrivateKey (undefined :: AES256)
+>   let eMsg = encrypt privKey msg >>= decrypt privKey
+>   case eMsg of
+>     Left err -> error $ show err
+>     Right msg' -> do
+>       putStrLn $ "Original Message: " ++ show msg
+>       putStrLn $ "Message after encryption & decryption: " ++ show msg'
+>
+> -- | More Examples... ?
 
 |-}
 
-module Crypto.Tutorial () where
-
-import Crypto.Cipher.Types
+module Crypto.Tutorial.General where