bech32

commit eee8c7a53ce709b62f86654c53677e47c66e1249
parent 7b6bfc359adb5f1b9eda4301ab835af41b0b2fe7
Author: Jared Tobin <jared@jtobin.io>
Date:   Sat, 10 Oct 2026 15:22:16 +0400

lib: mask as_base32 input to five bits

Diffstat:
M
lib/Data/ByteString/Bech32/Internal.hs
 | 
4
++--

1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/Data/ByteString/Bech32/Internal.hs b/lib/Data/ByteString/Bech32/Internal.hs
@@ -54,7 +54,7 @@ as_word5 (BI.PS sfp soff l) = case dec_tab of
     pure $! if ok then Just (BI.PS fp 0 l) else Nothing
 
 -- | Translate a 5-bit-value bytestring to its bech32 base32
---   bytestring.
+--   bytestring.  Only the low 5 bits of each input byte are used.
 as_base32 :: BS.ByteString -> BS.ByteString
 as_base32 (BI.PS sfp soff l) = case enc_tab of
   BI.PS tfp toff _ ->
@@ -67,7 +67,7 @@ as_base32 (BI.PS sfp soff l) = case enc_tab of
               | i == l    = pure ()
               | otherwise = do
                   v <- peekElemOff sp i
-                  c <- peekElemOff tp (fi v)
+                  c <- peekElemOff tp (fi (v .&. 0x1f))
                   pokeElemOff dst i c
                   loop (i + 1)
         loop 0