bip32

commit 1034b9f27ba6a80a971925bb8a7880c7e579e51d
parent a787932e2836752bb2e12baaffd7ef79ddb19b37
Author: Jared Tobin <jared@jtobin.io>
Date:   Fri, 21 Feb 2025 10:04:11 +0400

lib: basic derivation path expression

Diffstat:
M
lib/Crypto/HDKey/BIP32.hs
 | 
19
+++++++++++++++++++

1 file changed, 19 insertions(+), 0 deletions(-)
diff --git a/lib/Crypto/HDKey/BIP32.hs b/lib/Crypto/HDKey/BIP32.hs
@@ -186,6 +186,25 @@ derive_pub HDKey {..} i = do
       child = ser32 i
   pure $ HDKey (Left key) depth (Just parent) child
 
+-- derivation path expression -------------------------------------------------
+
+data Path =
+    M
+  | !Path :| !Word32 -- hardened
+  | !Path :/ !Word32
+  deriving (Eq, Show)
+
+derive :: HDKey -> Path -> Maybe HDKey
+derive hd = go where
+  go = \case
+    M -> pure hd
+    pat :| i -> do
+      hdkey <- go pat
+      derive_priv hdkey (0x8000_0000 + i) -- 2 ^ 31
+    pat :/ i -> do
+      hdkey <- go pat
+      derive_priv hdkey i
+
 -- serialization --------------------------------------------------------------
 
 xpub :: HDKey -> BS.ByteString