Encrypt wp notifications

Author: p1gp1g

simplexmq.cabal

@@ -292,6 +292,7 @@ library
     , attoparsec ==0.14.*
     , base >=4.14 && <5
     , base64-bytestring >=1.0 && <1.3
+    , binary ==0.8.*
     , composition ==1.0.*
     , constraints >=0.12 && <0.14
     , containers ==0.6.*

src/Simplex/Messaging/Crypto.hs

@@ -127,6 +127,7 @@ module Simplex.Messaging.Crypto
     encryptAEAD,
     decryptAEAD,
     encryptAESNoPad,
+    encryptAES128NoPad,
     decryptAESNoPad,
     authTagSize,
     randomAesKey,
@@ -209,7 +210,7 @@ import Control.Exception (Exception)
 import Control.Monad
 import Control.Monad.Except
 import Control.Monad.Trans.Except
-import Crypto.Cipher.AES (AES256)
+import Crypto.Cipher.AES (AES256, AES128)
 import qualified Crypto.Cipher.Types as AES
 import qualified Crypto.Cipher.XSalsa as XSalsa
 import qualified Crypto.Error as CE
@@ -895,6 +896,8 @@ data CryptoError
     CERatchetEarlierMessage Word32
   | -- | duplicate message number
     CERatchetDuplicateMessage
+  | -- | unable to decode ecc key
+    CryptoInvalidECCKey CE.CryptoError
   deriving (Eq, Show, Exception)
 
 aesKeySize :: Int
@@ -1021,11 +1024,22 @@ encryptAESNoPad :: Key -> GCMIV -> ByteString -> ExceptT CryptoError IO (AuthTag
 encryptAESNoPad key iv = encryptAEADNoPad key iv ""
 {-# INLINE encryptAESNoPad #-}
 
+-- Used to encrypt WebPush notifications
+-- This function requires 12 bytes IV, it does not transform IV.
+encryptAES128NoPad :: Key -> GCMIV -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
+encryptAES128NoPad key iv = encryptAEAD128NoPad key iv ""
+{-# INLINE encryptAES128NoPad #-}
+
 encryptAEADNoPad :: Key -> GCMIV -> ByteString -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
 encryptAEADNoPad aesKey ivBytes ad msg = do
   aead <- initAEADGCM aesKey ivBytes
   pure . first AuthTag $ AES.aeadSimpleEncrypt aead ad msg authTagSize
 
+encryptAEAD128NoPad :: Key -> GCMIV -> ByteString -> ByteString -> ExceptT CryptoError IO (AuthTag, ByteString)
+encryptAEAD128NoPad aesKey ivBytes ad msg = do
+  aead <- initAEAD128GCM aesKey ivBytes
+  pure . first AuthTag $ AES.aeadSimpleEncrypt aead ad msg authTagSize
+
 -- | AEAD-GCM decryption with associated data.
 --
 -- Used as part of double ratchet encryption.
@@ -1125,6 +1139,12 @@ initAEADGCM (Key aesKey) (GCMIV ivBytes) = cryptoFailable $ do
   cipher <- AES.cipherInit aesKey
   AES.aeadInit AES.AEAD_GCM cipher ivBytes
 
+-- this function requires 12 bytes IV, it does not transforms IV.
+initAEAD128GCM :: Key -> GCMIV -> ExceptT CryptoError IO (AES.AEAD AES128)
+initAEAD128GCM (Key aesKey) (GCMIV ivBytes) = cryptoFailable $ do
+  cipher <- AES.cipherInit aesKey
+  AES.aeadInit AES.AEAD_GCM cipher ivBytes
+
 -- | Random AES256 key.
 randomAesKey :: TVar ChaChaDRG -> STM Key
 randomAesKey = fmap Key . randomBytes aesKeySize

src/Simplex/Messaging/Notifications/Server/Push/WebPush.hs

@@ -9,10 +9,12 @@
 {-# HLINT ignore "Use newtype instead of data" #-}
 {-# LANGUAGE OverloadedRecordDot #-}
 {-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 
 module Simplex.Messaging.Notifications.Server.Push.WebPush where
 
 import Network.HTTP.Client
+import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Notifications.Protocol (DeviceToken (WPDeviceToken), WPEndpoint (..), encodePNMessages, PNMessageData)
 import Simplex.Messaging.Notifications.Server.Store.Types
 import Simplex.Messaging.Notifications.Server.Push
@@ -25,36 +27,126 @@ import Control.Exception ( fromException, SomeException, try )
 import qualified Network.HTTP.Types as N
 import qualified Data.Aeson as J
 import Data.Aeson ((.=))
+import qualified Data.Binary as Bin
+import qualified Data.Bits as Bits
+import qualified Data.ByteArray as BA
 import qualified Data.ByteString.Lazy as BL
 import Data.List.NonEmpty (NonEmpty)
 import qualified Data.Text.Encoding as T
 import qualified Data.Text as T
+import Control.Monad.Trans.Except (throwE)
+import Crypto.Hash.Algorithms (SHA256)
+import Crypto.Random (MonadRandom(getRandomBytes))
+import qualified Crypto.Cipher.Types as CT
+import qualified Crypto.Error as CE
+import qualified Crypto.MAC.HMAC as HMAC
+import qualified Crypto.PubKey.ECC.DH as ECDH
+import qualified Crypto.PubKey.ECC.Types as ECC
+import GHC.Base (when)
 
 wpPushProviderClient :: Manager -> PushProviderClient
 wpPushProviderClient mg tkn pn = do
-      e <- B.unpack <$> endpoint tkn
-      r <- liftPPWPError $ parseUrlThrow e
+      e <- endpoint tkn
+      r <- liftPPWPError $ parseUrlThrow $ B.unpack e.endpoint
       logDebug $ "Request to " <> tshow r.host
+      encBody <- body e
       let requestHeaders = [
             ("TTL", "2592000") -- 30 days
             , ("Urgency", "High")
             , ("Content-Encoding", "aes128gcm")
         -- TODO: topic for pings and interval
             ]
-      let req = r {
+          req = r {
         method = "POST"
         , requestHeaders
-        , requestBody = RequestBodyLBS $ encodePN pn
+        , requestBody = RequestBodyBS encBody
         , redirectCount = 0
       }
       _ <- liftPPWPError $ httpNoBody req mg
       pure ()
   where
-    endpoint :: NtfTknRec -> ExceptT PushProviderError IO B.ByteString
+    endpoint :: NtfTknRec -> ExceptT PushProviderError IO WPEndpoint
     endpoint NtfTknRec {token} = do
       case token of
-        WPDeviceToken WPEndpoint{ endpoint = e } -> pure e
+        WPDeviceToken e -> pure e
         _ -> fail "Wrong device token"
+    -- TODO: move to PPIndalidPusher ? WPEndpoint should be invalidated and removed if the key is invalid, but the validation key is never sent
+    body :: WPEndpoint -> ExceptT PushProviderError IO B.ByteString
+    body e = withExceptT PPCryptoError $ wpEncrypt e.auth e.p256dh (BL.toStrict $ encodePN pn)
+
+-- | encrypt :: auth -> key -> clear -> cipher
+-- | https://www.rfc-editor.org/rfc/rfc8291#section-3.4
+wpEncrypt :: B.ByteString -> B.ByteString -> B.ByteString -> ExceptT C.CryptoError IO B.ByteString
+wpEncrypt auth uaPubKS clearT = do
+  salt :: B.ByteString <- liftIO $ getRandomBytes 16
+  asPrivK <- liftIO $ ECDH.generatePrivate $ ECC.getCurveByName ECC.SEC_p256r1
+  uaPubK <- point uaPubKS
+  let asPubK = BL.toStrict . uncompressEncode . ECDH.calculatePublic (ECC.getCurveByName ECC.SEC_p256r1) $ asPrivK
+      ecdhSecret = ECDH.getShared (ECC.getCurveByName ECC.SEC_p256r1) asPrivK uaPubK
+      prkKey = hmac auth ecdhSecret
+      keyInfo = "WebPush: info\0" <> uaPubKS <> asPubK
+      ikm = hmac prkKey (keyInfo <> "\x01")
+      prk = hmac salt ikm
+      cekInfo = "Content-Encoding: aes128gcm\0" :: B.ByteString
+      cek = takeHM 16 $ hmac prk (cekInfo <> "\x01")
+      nonceInfo = "Content-Encoding: nonce\0" :: B.ByteString
+      nonce = takeHM 12 $ hmac prk (nonceInfo <> "\x01")
+      rs = BL.toStrict $ Bin.encode (4096 :: Bin.Word32) -- with RFC8291, it's ok to always use 4096 because there is only one single record and the final record can be smaller than rs (RFC8188)
+      idlen = BL.toStrict $ Bin.encode (65 :: Bin.Word8) -- with RFC8291, keyid is the pubkey, so always 65 bytes
+      header = salt <> rs <> idlen <> asPubK
+  iv <- ivFrom nonce
+  -- The last record uses a padding delimiter octet set to the value 0x02
+  (C.AuthTag (CT.AuthTag tag), cipherT) <- C.encryptAES128NoPad (C.Key cek) iv $ clearT <> "\x02"
+  pure $ header <> cipherT <> BA.convert tag
+  where
+    point :: B.ByteString -> ExceptT C.CryptoError IO ECC.Point
+    point s = withExceptT C.CryptoInvalidECCKey $ uncompressDecode $ BL.fromStrict s
+    hmac k v = HMAC.hmac k v :: HMAC.HMAC SHA256
+    takeHM :: Int -> HMAC.HMAC SHA256 -> B.ByteString
+    takeHM n v = BL.toStrict $ BL.pack $ take n $ BA.unpack v
+    ivFrom :: B.ByteString -> ExceptT C.CryptoError IO C.GCMIV
+    ivFrom s = case C.gcmIV s of
+      Left e -> throwE e
+      Right iv -> pure iv
+
+-- | Elliptic-Curve-Point-to-Octet-String Conversion without compression
+-- | as required by RFC8291
+-- | https://www.secg.org/sec1-v2.pdf#subsubsection.2.3.3
+uncompressEncode :: ECC.Point -> BL.ByteString
+uncompressEncode (ECC.Point x y) = "\x04" <>
+                                     encodeBigInt x <>
+                                     encodeBigInt y
+uncompressEncode ECC.PointO = "\0"
+
+uncompressDecode :: BL.ByteString -> ExceptT CE.CryptoError IO ECC.Point
+uncompressDecode "\0" = pure ECC.PointO
+uncompressDecode s = do
+  when (BL.take 1 s /= prefix) $ throwError CE.CryptoError_PointFormatUnsupported
+  when (BL.length s /= 65) $ throwError CE.CryptoError_KeySizeInvalid
+  let s' = BL.drop 1 s
+  x <- decodeBigInt $ BL.take 32 s'
+  y <- decodeBigInt $ BL.drop 32 s'
+  pure $ ECC.Point x y
+  where
+    prefix = "\x04" :: BL.ByteString
+
+encodeBigInt :: Integer -> BL.ByteString
+encodeBigInt i = do
+  let s1 = Bits.shiftR i 64
+      s2 = Bits.shiftR s1 64
+      s3 = Bits.shiftR s2 64
+  Bin.encode ( w64 s3, w64 s2, w64 s1, w64 i )
+  where
+    w64 :: Integer -> Bin.Word64
+    w64 = fromIntegral
+
+decodeBigInt :: BL.ByteString -> ExceptT CE.CryptoError IO Integer
+decodeBigInt s = do
+  when (BL.length s /= 32) $ throwError CE.CryptoError_PointSizeInvalid
+  let (w3, w2, w1, w0) = Bin.decode s :: (Bin.Word64, Bin.Word64, Bin.Word64, Bin.Word64 )
+  pure $ shift 3 w3 + shift 2 w2 + shift 1 w1 + shift 0 w0
+  where
+    shift i w = Bits.shiftL (fromIntegral w) (64*i)
 
 encodePN :: PushNotification -> BL.ByteString
 encodePN pn = J.encode $ case pn of