librustzcash-wrapper/src/lib.rs

@@ -632,3 +632,19 @@ pub extern "C" fn rust_wrapper_derive_orchard_spending_key(
         }
     }
 }
+
+#[no_mangle]
+pub extern "C" fn rust_wrapper_derive_orchard_receiver(
+    spend_key: *const u8,
+    spend_key_len: usize,
+    add_id: u32,
+    out: *mut u8,
+    out_len: &mut usize
+    ){
+    let sk_in: Vec<u8> = marshall_from_haskell_var(spend_key, spend_key_len, RW);
+    let sk = SpendingKey::from_bytes(sk_in[0..32].try_into().unwrap()).unwrap();
+    let fvk = FullViewingKey::from(&sk);
+    let o_rec = fvk.address_at(add_id, Scope::External);
+    marshall_to_haskell_var(&o_rec.to_raw_address_bytes().to_vec(), out, out_len, RW);
+
+}

src/C/Zcash.chs

@@ -142,3 +142,11 @@ import ZcashHaskell.Types
      }
   -> `()'
 #}
+
+{# fun unsafe rust_wrapper_derive_orchard_receiver as rustWrapperGenOrchardReceiver
+     { toBorshVar* `BS.ByteString'&
+     , `Word32'
+     , getVarBuffer `Buffer (BS.ByteString)'&
+     }
+  -> `()'
+#}

src/ZcashHaskell/Orchard.hs

@@ -18,7 +18,8 @@
 module ZcashHaskell.Orchard where
 
 import C.Zcash
-  ( rustWrapperGenOrchardSpendKey
+  ( rustWrapperGenOrchardReceiver
+  , rustWrapperGenOrchardSpendKey
   , rustWrapperOrchardCheck
   , rustWrapperOrchardNoteDecode
   , rustWrapperUADecode
@@ -34,7 +35,8 @@ import ZcashHaskell.Types
 import ZcashHaskell.Utils (encodeBech32m, f4Jumble)
 
 -- | Derives an Orchard spending key for the given seed and account ID
-genOrchardSpendingKey :: Seed -> CoinType -> AccountId -> Maybe BS.ByteString
+genOrchardSpendingKey ::
+     Seed -> CoinType -> AccountId -> Maybe OrchardSpendingKey
 genOrchardSpendingKey s coinType accountId =
   if BS.length k /= 32
     then Nothing
@@ -47,6 +49,17 @@ genOrchardSpendingKey s coinType accountId =
         (getValue coinType)
         (fromIntegral accountId)
 
+-- | Derives an Orchard receiver for the given spending key and index
+genOrchardReceiver :: Int -> OrchardSpendingKey -> Maybe OrchardReceiver
+genOrchardReceiver i osk =
+  if BS.length k /= 43
+    then Nothing
+    else Just k
+  where
+    k =
+      withPureBorshVarBuffer $
+      rustWrapperGenOrchardReceiver osk (fromIntegral i)
+
 -- | Checks if given bytestring is a valid encoded unified address
 isValidUnifiedAddress :: BS.ByteString -> Maybe UnifiedAddress
 isValidUnifiedAddress str =