ppad-sha256 0.3.2 → 0.3.3
raw patch · 4 files changed
+74/−4 lines, 4 filesPVP ok
version bump matches the API change (PVP)
API changes (from Hackage documentation)
Files
- CHANGELOG +7/−0
- lib/Crypto/Hash/SHA256/Arm.hs +0/−1
- lib/Crypto/Hash/SHA256/Internal.hs +66/−2
- ppad-sha256.cabal +1/−1
CHANGELOG view
@@ -1,5 +1,12 @@ # Changelog +- 0.3.3 (2026-07-06)+ * The constant-time 'Eq' on 'MAC' now folds over the two buffers+ directly, rather than materialising an intermediate ByteString+ holding their XOR on the heap. Semantics are unchanged.++ * Improves the performance of constant-time MAC comparison.+ - 0.3.2 (2026-02-01) * The library has been refactored substantially to achieve greater control over heap allocation, particularly around HMAC calculation.
lib/Crypto/Hash/SHA256/Arm.hs view
@@ -46,7 +46,6 @@ fi = fromIntegral {-# INLINE fi #-} - peek_registers :: Ptr Word32 -> Registers
lib/Crypto/Hash/SHA256/Internal.hs view
@@ -83,8 +83,37 @@ -- -- Runs in variable-time only for invalid inputs. (MAC a@(BI.PS _ _ la)) == (MAC b@(BI.PS _ _ lb))- | la /= lb = False- | otherwise = BS.foldl' (B..|.) 0 (BS.packZipWith B.xor a b) == 0+ | la /= lb = False+ | la == 32 =+ -- fully-unrolled, fixed OR-tree over four 64-bit lanes.+ -- A standard 32-byte MAC folds through no loop-carried+ -- accumulator, so there is no per-byte accumulator whose+ -- nonzero span tracks the position of a differing byte:+ -- the comparison time is independent of where (or whether)+ -- the tags differ.+ let !d0 = Exts.xor64# (word64le a 00) (word64le b 00)+ !d1 = Exts.xor64# (word64le a 08) (word64le b 08)+ !d2 = Exts.xor64# (word64le a 16) (word64le b 16)+ !d3 = Exts.xor64# (word64le a 24) (word64le b 24)+ !d = (d0 `Exts.or64#` d1) `Exts.or64#`+ (d2 `Exts.or64#` d3)+ in Exts.isTrue# (Exts.eqWord64# d (Exts.wordToWord64# 0##))+ | otherwise = go 0 0+ where+ -- byte-serial fallback for nonstandard MAC lengths. 'hmac'+ -- always yields 32 bytes, so this path is unreachable through+ -- it; it exists only to keep the instance total for MACs built+ -- directly via the exported constructor. The fused fold ORs the+ -- bytewise XORs into an accumulator directly, rather than via+ -- packZipWith, so no intermediate ByteString holding the+ -- (secret-derived) difference bytes is ever materialised.+ go :: Word8 -> Int -> Bool+ go !acc !i+ | i == la = acc == 0+ | otherwise =+ let !x = BU.unsafeIndex a i+ !y = BU.unsafeIndex b i+ in go (acc B..|. B.xor x y) (i + 1) -- | SHA256 block. newtype Block = Block@@ -172,6 +201,41 @@ !sc = Exts.uncheckedShiftLWord32# c 08# in sa `Exts.orWord32#` sb `Exts.orWord32#` sc `Exts.orWord32#` d {-# INLINE word32be #-}++-- | Assemble the 64-bit word at the given byte offset, little-endian.+--+-- Byte order is immaterial to an equality test as long as both+-- operands are assembled the same way; this is used only by the+-- constant-time 'MAC' comparison. The length is not checked.+word64le :: BS.ByteString -> Int -> Exts.Word64#+word64le bs m =+ let !(GHC.Word.W8# r0) = BU.unsafeIndex bs m+ !(GHC.Word.W8# r1) = BU.unsafeIndex bs (m + 1)+ !(GHC.Word.W8# r2) = BU.unsafeIndex bs (m + 2)+ !(GHC.Word.W8# r3) = BU.unsafeIndex bs (m + 3)+ !(GHC.Word.W8# r4) = BU.unsafeIndex bs (m + 4)+ !(GHC.Word.W8# r5) = BU.unsafeIndex bs (m + 5)+ !(GHC.Word.W8# r6) = BU.unsafeIndex bs (m + 6)+ !(GHC.Word.W8# r7) = BU.unsafeIndex bs (m + 7)+ !w0 = Exts.word8ToWord# r0+ !w1 = Exts.word8ToWord# r1+ !w2 = Exts.word8ToWord# r2+ !w3 = Exts.word8ToWord# r3+ !w4 = Exts.word8ToWord# r4+ !w5 = Exts.word8ToWord# r5+ !w6 = Exts.word8ToWord# r6+ !w7 = Exts.word8ToWord# r7+ !s1 = Exts.uncheckedShiftL# w1 8#+ !s2 = Exts.uncheckedShiftL# w2 16#+ !s3 = Exts.uncheckedShiftL# w3 24#+ !s4 = Exts.uncheckedShiftL# w4 32#+ !s5 = Exts.uncheckedShiftL# w5 40#+ !s6 = Exts.uncheckedShiftL# w6 48#+ !s7 = Exts.uncheckedShiftL# w7 56#+ in Exts.wordToWord64#+ (w0 `Exts.or#` s1 `Exts.or#` s2 `Exts.or#` s3 `Exts.or#`+ s4 `Exts.or#` s5 `Exts.or#` s6 `Exts.or#` s7)+{-# INLINE word64le #-} -- parsing (final input) ------------------------------------------------------
ppad-sha256.cabal view
@@ -1,6 +1,6 @@ cabal-version: 3.0 name: ppad-sha256-version: 0.3.2+version: 0.3.3 synopsis: The SHA-256 and HMAC-SHA256 algorithms license: MIT license-file: LICENSE