secp256k1

commit 9603f1e4a327c3007df36f7afdc16954eefcf314
parent edf681f4a679a52118d0c750572e3efb5b9439f3
Author: Jared Tobin <jared@jtobin.io>
Date:   Mon, 25 Nov 2024 15:40:04 +0400

lib: add wnaf-powered derive_pub

Diffstat:
M
bench/Main.hs
 | 
11
++++++++---
M
lib/Crypto/Curve/Secp256k1.hs
 | 
17
+++++++++++++++++
M
test/Main.hs
 | 
2
--

3 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/bench/Main.hs b/bench/Main.hs
@@ -92,14 +92,19 @@ mul_wnaf = env setup $ \ ~(tex, x) ->
       pure (tex, int)
 
 derive_pub :: Benchmark
-derive_pub = env setup $ \x ->
+derive_pub = env setup $ \ ~(tex, x) ->
     bgroup "derive_pub" [
       bench "sk = 2" $ nf S.derive_pub 2
     , bench "sk = 2 ^ 255 - 19" $ nf S.derive_pub x
+    , bench "wnaf, sk = 2" $ nf (S.derive_pub' tex) 2
+    , bench "wnaf, sk = 2 ^ 255 - 19" $ nf (S.derive_pub' tex) x
     ]
   where
-    setup = pure . S.parse_int256 $ B16.decodeLenient
-      "7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffed"
+    setup = do
+      let !tex = S.precompute
+          !int = S.parse_int256 $ B16.decodeLenient
+            "7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffed"
+      pure (tex, int)
 
 schnorr :: Benchmark
 schnorr = env setup $ \ ~(tex, big) ->
diff --git a/lib/Crypto/Curve/Secp256k1.hs b/lib/Crypto/Curve/Secp256k1.hs
@@ -24,6 +24,7 @@ module Crypto.Curve.Secp256k1 (
   -- * secp256k1 points
     Pub
   , derive_pub
+  , derive_pub'
 
   -- * Parsing
   , parse_int256
@@ -680,6 +681,22 @@ derive_pub _SECRET
       mul _CURVE_G _SECRET
 {-# NOINLINE derive_pub #-}
 
+-- | The same as 'derive_pub', except uses a 'Context' to optimise
+--   internal calculations.
+--
+--   >>> import qualified System.Entropy as E
+--   >>> sk <- fmap parse_int256 (E.getEntropy 32)
+--   >>> let !tex = precompute
+--   >>> derive_pub' tex sk
+--   "<secp256k1 point>"
+derive_pub' :: Context -> Integer -> Pub
+derive_pub' tex _SECRET
+  | not (ge _SECRET) =
+      error "ppad-secp256k1 (derive_pub): invalid secret key"
+  | otherwise =
+      mul_wnaf tex _SECRET
+{-# NOINLINE derive_pub' #-}
+
 -- parsing --------------------------------------------------------------------
 
 -- | Parse a positive 256-bit 'Integer', /e.g./ a Schnorr or ECDSA
diff --git a/test/Main.hs b/test/Main.hs
@@ -69,7 +69,6 @@ parse_point_tests = testGroup "parse_point tests" [
 render :: Show a => a -> String
 render = filter (`notElem` ("\"" :: String)) . show
 
--- XX replace these with something non-stupid
 parse_point_test_p :: TestTree
 parse_point_test_p = testCase (render p_hex) $
   case parse_point (B16.decodeLenient p_hex) of
@@ -88,7 +87,6 @@ parse_point_test_r = testCase (render r_hex) $
     Nothing -> assertFailure "bad parse"
     Just r  -> assertEqual mempty r_pro r
 
--- XX also make less dumb
 add_tests :: TestTree
 add_tests = testGroup "ec addition" [
     add_test_pq