Turn nonce into a non-effect constant using FFI

src/Logic.purs

@@ -2,7 +2,7 @@ module Aviary.Logic where
 
 import Prelude
 import AviaryFormat.Format (Format, Image, Index, parseIndex) as Format
-import Aviary.FFI (arrayBufferToBlob)
+import Aviary.FFI (arrayBufferToBlob, nonce)
 import Aviary.Model (formatToMime, GalleryError(..), Image, ImageData(..), ImageError(..), Model(..))
 
 import Control.Monad.Error.Class (try)
@@ -16,11 +16,10 @@ import Data.Either (Either(..), note)
 import Data.Maybe (Maybe(..))
 import Data.Newtype (unwrap)
 import Data.ArrayBuffer.ArrayBuffer (byteLength)
-import Data.ArrayBuffer.Builder (DataBuff, execPut, putDataBuff, putInt8)
+import Data.ArrayBuffer.Builder (DataBuff, execPut, putDataBuff)
 import Data.ArrayBuffer.DataView (whole)
 import Data.ArrayBuffer.Types (ArrayBuffer)
 import Data.Filterable (partitionMap)
-import Data.Foldable (traverse_)
 import Data.String (drop)
 import Parsing (runParserT)
 import Web.File.Url (createObjectURL)
@@ -34,9 +33,6 @@ import Crypto.Subtle.Key.Import (aes)
 import Crypto.Subtle.Key.Import (importKey) as SC
 import Crypto.Subtle.Key.Types (CryptoKey, decrypt, raw)
 
-nonceE :: Effect ArrayBuffer
-nonceE = execPut $ traverse_ putInt8 [0xd0, 0xc3, 0x75, 0x56, 0x58, 0xc1, 0x7e, 0x5f, 0xd6, 0xcc, 0xb6, 0x76]
-
 databuffToBuffer :: DataBuff -> Effect ArrayBuffer
 databuffToBuffer = execPut <<< putDataBuff
 
@@ -49,7 +45,6 @@ importKey key =
 
 decryptBlob :: CryptoKey -> ArrayBuffer -> ArrayBuffer -> Aff ArrayBuffer
 decryptBlob key cyphertext nonce =
-    -- nonce <- makeAff (\_ -> nonceE)
     Alg.decrypt (Alg.aesGCM nonce Nothing (Just t128)) key cyphertext
 
 convertImageFromProtobuf :: Format.Image -> Either GalleryError Image
@@ -103,8 +98,7 @@ fetch_gallery_from_page_info = do
         keyB64 <- drop 1 <$> Location.hash location
         server <- Location.origin location
         fileId <- drop 1 <$> Location.pathname location
-        nonce <- nonceE
-        pure {keyB64, server, fileId, nonce}
+        pure {keyB64, server, fileId}
     case decodeKey urlInfo.keyB64 of
         Nothing -> pure $ GError MalformedKey
         Just keyBuffer -> do
@@ -113,7 +107,7 @@ fetch_gallery_from_page_info = do
             case status of
                 200 -> do
                     encryptedIndex <- arrayBuffer
-                    serializedIndex <- try $ decryptBlob cryptoKey encryptedIndex urlInfo.nonce
+                    serializedIndex <- try $ decryptBlob cryptoKey encryptedIndex nonce
                     case serializedIndex of
                         Left _ -> pure $ GError DecryptFailed
                         Right serializedIndex' -> do

src/ffi.js

@@ -3,3 +3,5 @@ export function arrayBufferToBlob(mime) {
 		return new Blob([data], {type: mime})
 	}
 }
+
+export const nonce = new Uint8Array([0xd0, 0xc3, 0x75, 0x56, 0x58, 0xc1, 0x7e, 0x5f, 0xd6, 0xcc, 0xb6, 0x76]).buffer

src/ffi.purs

@@ -6,3 +6,5 @@ import Web.File.Blob (Blob)
 -- mimeType :: String
 -- blobData :: ArrayBuffer
 foreign import arrayBufferToBlob :: String -> ArrayBuffer -> Blob
+
+foreign import nonce :: ArrayBuffer