sha512

commit 7e214478aabed3a0875f4754317bbf1019087a61
parent d0f188b8d2b520aa3556f8437db11d4b488a9975
Author: Jared Tobin <jared@jtobin.io>
Date:   Mon,  6 Jan 2025 23:34:00 -0330

lib: minor optimisation

Avoid calls to BS.length, preferring pattern synonym.

Diffstat:
M
lib/Crypto/Hash/SHA512.hs
 | 
30
++++++++++++------------------

1 file changed, 12 insertions(+), 18 deletions(-)
diff --git a/lib/Crypto/Hash/SHA512.hs b/lib/Crypto/Hash/SHA512.hs
@@ -83,14 +83,14 @@ unsafe_splitAt n (BI.BS x l) =
 splitAt128 :: BL.ByteString -> SLPair
 splitAt128 = splitAt' (128 :: Int) where
   splitAt' _ BLI.Empty        = SLPair mempty BLI.Empty
-  splitAt' n (BLI.Chunk c cs) =
-    if    n < BS.length c
+  splitAt' n (BLI.Chunk c@(BI.PS _ _ l) cs) =
+    if    n < l
     then
       -- n < BS.length c, so unsafe_splitAt is safe
       let !(SSPair c0 c1) = unsafe_splitAt n c
       in  SLPair c0 (BLI.Chunk c1 cs)
     else
-      let SLPair cs' cs'' = splitAt' (n - BS.length c) cs
+      let SLPair cs' cs'' = splitAt' (n - l) cs
       in  SLPair (c <> cs') cs''
 
 -- variant of Data.ByteString.splitAt that behaves like an incremental
@@ -116,10 +116,8 @@ sol l =
 
 -- RFC 6234 4.1 (strict)
 pad :: BS.ByteString -> BS.ByteString
-pad m = BL.toStrict . BSB.toLazyByteString $ padded where
-  l = fi (BS.length m)
+pad m@(BI.PS _ _ (fi -> l)) = BL.toStrict . BSB.toLazyByteString $ padded where
   padded = BSB.byteString m <> fill (sol l) (BSB.word8 0x80)
-
   fill j !acc
     | j == 0 = acc <> BSB.word64BE 0x00 <> BSB.word64BE (l * 8)
     | otherwise = fill (pred j) (acc <> BSB.word8 0x00)
@@ -513,7 +511,7 @@ hmac
   :: BS.ByteString -- ^ key
   -> BS.ByteString -- ^ text
   -> BS.ByteString
-hmac mk text =
+hmac mk@(BI.PS _ _ l) text =
     let step1 = k <> BS.replicate (128 - lk) 0x00
         step2 = BS.map (B.xor 0x36) step1
         step3 = step2 <> text
@@ -522,11 +520,9 @@ hmac mk text =
         step6 = step5 <> step4
     in  hash step6
   where
-    !(KeyAndLen k lk) =
-      let l = BS.length mk
-      in  if   l > 128
-          then KeyAndLen (hash mk) 64
-          else KeyAndLen mk l
+    !(KeyAndLen k lk)
+      | l > 128   = KeyAndLen (hash mk) 64
+      | otherwise = KeyAndLen mk l
 
 -- | Produce a message authentication code for a lazy bytestring, based
 --   on the provided (strict, bytestring) key, via SHA-512.
@@ -542,7 +538,7 @@ hmac_lazy
   :: BS.ByteString -- ^ key
   -> BL.ByteString -- ^ text
   -> BS.ByteString
-hmac_lazy mk text =
+hmac_lazy mk@(BI.PS _ _ l) text =
     let step1 = k <> BS.replicate (128 - lk) 0x00
         step2 = BS.map (B.xor 0x36) step1
         step3 = BL.fromStrict step2 <> text
@@ -551,9 +547,7 @@ hmac_lazy mk text =
         step6 = step5 <> step4
     in  hash step6
   where
-    !(KeyAndLen k lk) =
-      let l = BS.length mk
-      in  if   l > 128
-          then KeyAndLen (hash mk) 64
-          else KeyAndLen mk l
+    !(KeyAndLen k lk)
+      | l > 128   = KeyAndLen (hash mk) 64
+      | otherwise = KeyAndLen mk l