add demo application

README.md

@@ -12,6 +12,8 @@ This codebase is primarily a personal project, initiated for the purpose of lear
 
 ## Features
 
+- Salsa20 Encryption and Decryption Demo: Explore the Salsa20 encryption and decryption application by running the `stack run` command.
+
 - Extensive Testing: The project includes a comprehensive suite of tests to ensure code quality. You can run the tests locally using `stack test` or `cabal test`. The CI (Continuous Integration) pipeline also runs most of these tests.
 
 ## Tutorial

app/Main.hs

@@ -1,6 +1,99 @@
+{-|
+Salsa20 Encryption and Decryption Application
+
+This Haskell program demonstrates the encryption and decryption of messages using the Salsa20 stream cipher.
+The application takes a user-provided secret key phrase and a message as input, performs encryption,
+and then decrypts the message to demonstrate the Salsa20 algorithm.
+
+The code uses the Salsa20 implementation from the hsalsa Crypt module, SHA256 for key hashing, Crypto.Nonce for
+nonce generation, and base64-bytestring for encoding.
+
+Based in https://asecuritysite.com/encryption/salsa20
+-}
 module Main (main) where
 
+import Data.Word
+import Data.Char (ord)
+import qualified Data.ByteString
+import qualified Crypto.Hash.SHA256 as SHA256
+import Crypto.Nonce
+import Data.ByteString.Base64
+import Data.List.Split
+
+import Crypt
+
 main :: IO ()
 main = do
-    putStrLn "Salsa20 in haskell - Category theory"
+    putStrLn "---Salsa20 encryption and decryption"
+    putStrLn ""
+
+    key <- getInput "Insert your secret key phrase:"
+    message <- getInput "Insert message to be encrypted or decrypted:"
+
+    printInfo ["", "Plain text: " ++ message, "Secret key: " ++ key]
+
+    let messageBytes = intToWord32 $ stringToBytes message
+
+    let keyHash = Data.ByteString.unpack $ SHA256.hash (Data.ByteString.pack (intToWord8 (stringToBytes key)))
+    let keyB64 = Data.ByteString.Base64.encode $ Data.ByteString.pack keyHash
+
+    printInfo ["Key used: " ++ byteStringtoCharList keyB64, "", "---Salsa20 Encrypt"]
+
+    g <- Crypto.Nonce.new
+    nonce <- Crypto.Nonce.nonce128 g
+
+    let unpackedNonce = Data.ByteString.unpack nonce
+    -- We just need half of the nonce so we split it in two and take the first half
+    let nonces = Data.List.Split.chunksOf 8 unpackedNonce
+    let nonceB64 = Data.ByteString.Base64.encode $ Data.ByteString.pack (head nonces)
+
+    putStrLn ("Nonce: " ++ byteStringtoCharList nonceB64)
+
+    -- Our API accepts 2 keys of 16 bytes each so we split the 32 bytes generated by the hash in two
+    let keys = Data.List.Split.chunksOf 16 keyHash
+    let key1 = keys!!0
+    let key2 = keys!!1
+
+    let nonceAsList = word8ToWord32 (head nonces)
+
+    -- TODO: The API is ugly: 
+    -- - We should be able to pass the nonce, keys and message as a strings and the API should convert it?
+    -- - The `0` at the end should not be needed?
+    -- - etc
+    let v2encrypted = cryptBlock32Compute messageBytes (word8ToWord32 key1) (word8ToWord32 key2) nonceAsList 0
+
+    let b64_cipher = Data.ByteString.Base64.encode $ Data.ByteString.pack (word32ToWord8 v2encrypted)
+    printInfo ["Ciphertext: " ++ byteStringtoCharList b64_cipher, "", "---Salsa20 Decrypt"]
+
+    let v2decrypted = cryptBlock32Compute v2encrypted (word8ToWord32 key1) (word8ToWord32 key2) nonceAsList 0
+
+    let b64_decrypted = Data.ByteString.pack (word32ToWord8 v2decrypted)
+
+    putStrLn ("Decrypted: " ++ byteStringtoCharList b64_decrypted)
+
     return ()
+
+    where
+        getInput prompt = do
+            putStrLn prompt
+            getLine
+
+        printInfo = mapM_ putStrLn
+
+        stringToBytes :: String -> [Int]
+        stringToBytes = map ord
+
+        intToWord32 :: [Int] -> [Word32]
+        intToWord32 = map fromIntegral
+
+        intToWord8 :: [Int] -> [Word8]
+        intToWord8 = map fromIntegral
+
+        byteStringtoCharList :: Data.ByteString.ByteString -> [Char]
+        byteStringtoCharList = map (toEnum . fromEnum) . Data.ByteString.unpack
+
+        word8ToWord32 :: [Word8] -> [Word32]
+        word8ToWord32 = map fromIntegral
+
+        word32ToWord8 :: [Word32] -> [Word8]
+        word32ToWord8 = map fromIntegral

package.yaml

@@ -50,6 +50,10 @@ executables:
     dependencies:
     - salsa20
     - split
+    - cryptohash-sha256
+    - bytestring
+    - nonce
+    - base64-bytestring
 
 tests:
   salsa20-fast-unit-tests:

salsa20.cabal

@@ -54,7 +54,11 @@ executable salsa20-exe
   ghc-options: -Wall -Wcompat -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-export-lists -Wmissing-home-modules -Wpartial-fields -Wredundant-constraints -threaded -rtsopts -with-rtsopts=-N
   build-depends:
       base >=4.7 && <5
+    , base64-bytestring
+    , bytestring
+    , cryptohash-sha256
     , keelung
+    , nonce
     , salsa20
     , split
     , text

src/Hash.hs

@@ -70,7 +70,7 @@ salsa20Compute input rounds
     | length input == 64 = aument $ coreCompute (Utils.reduce input) rounds
     | otherwise = error "input to `salsa20Compute` must be a list of 64 `Word32` numbers"
 
--- |The salsa20 expression as a string using `core1Display` which is only one round of doubleround.
+-- |The salsa20 expression as a string using `coreDisplay`. Call with r = 1, which is one round of doubleround.
 salsa20Display :: [String] -> Int -> [String]
 salsa20Display input rounds
     | length input == 64 = aumentDisplay $ coreDisplay (reduceDisplay input) rounds