librustzcash-wrapper/src/lib.rs

@@ -625,7 +625,7 @@ pub extern "C" fn rust_wrapper_derive_orchard_spending_key(
     let sk = SpendingKey::from_zip32_seed(&s, coin_type, zip32::AccountId::try_from(acc_id).unwrap());
     match sk {
         Ok(key) => {
-            marshall_to_haskell_var(&key.to_bytes(), out, out_len, RW);
+            marshall_to_haskell_var(&key.to_bytes().to_vec(), out, out_len, RW);
         },
         Err(_e) => {
             marshall_to_haskell_var(&vec![0], out, out_len, RW);

src/ZcashHaskell/Orchard.hs

@@ -34,10 +34,18 @@ import ZcashHaskell.Types
 import ZcashHaskell.Utils (encodeBech32m, f4Jumble)
 
 -- | Derives an Orchard spending key for the given seed and account ID
-genOrchardSpendingKey :: Seed -> CoinType -> AccountId -> BS.ByteString
+genOrchardSpendingKey :: Seed -> CoinType -> AccountId -> Maybe BS.ByteString
 genOrchardSpendingKey s coinType accountId =
-  withPureBorshVarBuffer $
-  rustWrapperGenOrchardSpendKey s (getValue coinType) (fromIntegral accountId)
+  if BS.length k /= 32
+    then Nothing
+    else Just k
+  where
+    k =
+      withPureBorshVarBuffer $
+      rustWrapperGenOrchardSpendKey
+        s
+        (getValue coinType)
+        (fromIntegral accountId)
 
 -- | Checks if given bytestring is a valid encoded unified address
 isValidUnifiedAddress :: BS.ByteString -> Maybe UnifiedAddress

test/Spec.hs

@@ -19,6 +19,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 
 import C.Zcash (rustWrapperUADecode)
+import Control.Monad.IO.Class (liftIO)
 import Data.Aeson
 import Data.Bool (Bool(True))
 import qualified Data.ByteString as BS
@@ -45,6 +46,7 @@ import ZcashHaskell.Sapling
 import ZcashHaskell.Transparent (encodeTransparent)
 import ZcashHaskell.Types
   ( BlockResponse(..)
+  , CoinType(..)
   , DecodedNote(..)
   , OrchardAction(..)
   , RawData(..)
@@ -453,6 +455,11 @@ main = do
         p <- generateWalletSeedPhrase
         let s = getWalletSeed p
         maybe 0 BS.length s `shouldBe` 64
+      it "Generate Orchard spending key" $ do
+        p <- generateWalletSeedPhrase
+        let s = getWalletSeed p
+        genOrchardSpendingKey (fromMaybe "" s) MainNetCoin 1 `shouldNotBe`
+          Nothing
     describe "Address tests" $ do
       it "Encode transparent" $ do
         let ua =