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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.
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Benjamin Peterson 2017-12-09 11:24:18 -08:00 committed by GitHub
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commit 4e3e156391
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2 changed files with 4 additions and 3 deletions
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Misc/NEWS.d/next/Core and Builtins/2017-12-09-11-03-51.bpo-32260.1DAO-p.rst Normal file
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@ -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.

4
Python/pyhash.c
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@ -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;