From 4e3e156391e70cd23cae18f2629ec323b3b1e7de Mon Sep 17 00:00:00 2001 From: Benjamin Peterson Date: Sat, 9 Dec 2017 11:24:18 -0800 Subject: [PATCH] bpo-32260: don't byte swap siphash keys (#4771) Reference siphash takes the keys as a bytes, so it makes sense to byte swap when reifying the keys as 64-bit integers. However, Python's siphash takes host integers in to start with. --- .../2017-12-09-11-03-51.bpo-32260.1DAO-p.rst | 3 +++ Python/pyhash.c | 4 +--- 2 files changed, 4 insertions(+), 3 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2017-12-09-11-03-51.bpo-32260.1DAO-p.rst diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-12-09-11-03-51.bpo-32260.1DAO-p.rst b/Misc/NEWS.d/next/Core and Builtins/2017-12-09-11-03-51.bpo-32260.1DAO-p.rst new file mode 100644 index 00000000000..523ffe0a611 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2017-12-09-11-03-51.bpo-32260.1DAO-p.rst @@ -0,0 +1,3 @@ +Don't byte swap the input keys to the SipHash algorithm on big-endian +platforms. This should ensure siphash gives consistent results across +platforms. diff --git a/Python/pyhash.c b/Python/pyhash.c index bc6786c7b8b..4494a2f6ef6 100644 --- a/Python/pyhash.c +++ b/Python/pyhash.c @@ -364,9 +364,7 @@ static PyHash_FuncDef PyHash_Func = {fnv, "fnv", 8 * SIZEOF_PY_HASH_T, static uint64_t -siphash24(uint64_t key0, uint64_t key1, const void *src, Py_ssize_t src_sz) { - uint64_t k0 = _le64toh(key0); - uint64_t k1 = _le64toh(key1); +siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) { uint64_t b = (uint64_t)src_sz << 56; const uint64_t *in = (uint64_t*)src;