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bpo-29410: Change the default hash algorithm to SipHash13. (GH-28752)

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Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>
Co-authored-by: Christian Heimes <christian@python.org>
This commit is contained in:
Inada Naoki 2021-10-10 17:29:46 +09:00 • committed by GitHub
parent a1c3c9e824
commit ad970e8623
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11 changed files with 123 additions and 26 deletions
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79
Python/pyhash.c
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@ -358,19 +358,72 @@ static PyHash_FuncDef PyHash_Func = {fnv, "fnv", 8 * SIZEOF_PY_HASH_T,
# define ROTATE(x, b) (uint64_t)( ((x) << (b)) | ( (x) >> (64 - (b))) )
#endif
#define HALF_ROUND(a,b,c,d,s,t) \
a += b; c += d; \
#define HALF_ROUND(a,b,c,d,s,t) \
a += b; c += d; \
b = ROTATE(b, s) ^ a; \
d = ROTATE(d, t) ^ c; \
a = ROTATE(a, 32);
#define DOUBLE_ROUND(v0,v1,v2,v3) \
HALF_ROUND(v0,v1,v2,v3,13,16); \
HALF_ROUND(v2,v1,v0,v3,17,21); \
HALF_ROUND(v0,v1,v2,v3,13,16); \
#define SINGLE_ROUND(v0,v1,v2,v3) \
HALF_ROUND(v0,v1,v2,v3,13,16); \
HALF_ROUND(v2,v1,v0,v3,17,21);
#define DOUBLE_ROUND(v0,v1,v2,v3) \
SINGLE_ROUND(v0,v1,v2,v3); \
SINGLE_ROUND(v0,v1,v2,v3);
static uint64_t
siphash13(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
uint64_t b = (uint64_t)src_sz << 56;
const uint8_t *in = (const uint8_t*)src;
uint64_t v0 = k0 ^ 0x736f6d6570736575ULL;
uint64_t v1 = k1 ^ 0x646f72616e646f6dULL;
uint64_t v2 = k0 ^ 0x6c7967656e657261ULL;
uint64_t v3 = k1 ^ 0x7465646279746573ULL;
uint64_t t;
uint8_t *pt;
while (src_sz >= 8) {
uint64_t mi;
memcpy(&mi, in, sizeof(mi));
mi = _le64toh(mi);
in += sizeof(mi);
src_sz -= sizeof(mi);
v3 ^= mi;
SINGLE_ROUND(v0,v1,v2,v3);
v0 ^= mi;
}
t = 0;
pt = (uint8_t *)&t;
switch (src_sz) {
case 7: pt[6] = in[6]; /* fall through */
case 6: pt[5] = in[5]; /* fall through */
case 5: pt[4] = in[4]; /* fall through */
case 4: memcpy(pt, in, sizeof(uint32_t)); break;
case 3: pt[2] = in[2]; /* fall through */
case 2: pt[1] = in[1]; /* fall through */
case 1: pt[0] = in[0]; /* fall through */
}
b |= _le64toh(t);
v3 ^= b;
SINGLE_ROUND(v0,v1,v2,v3);
v0 ^= b;
v2 ^= 0xff;
SINGLE_ROUND(v0,v1,v2,v3);
SINGLE_ROUND(v0,v1,v2,v3);
SINGLE_ROUND(v0,v1,v2,v3);
/* modified */
t = (v0 ^ v1) ^ (v2 ^ v3);
return t;
}
#if Py_HASH_ALGORITHM == Py_HASH_SIPHASH24
static uint64_t
siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
uint64_t b = (uint64_t)src_sz << 56;
@ -419,14 +472,26 @@ siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
t = (v0 ^ v1) ^ (v2 ^ v3);
return t;
}
#endif
uint64_t
_Py_KeyedHash(uint64_t key, const void *src, Py_ssize_t src_sz)
{
return siphash24(key, 0, src, src_sz);
return siphash13(key, 0, src, src_sz);
}
#if Py_HASH_ALGORITHM == Py_HASH_SIPHASH13
static Py_hash_t
pysiphash(const void *src, Py_ssize_t src_sz) {
return (Py_hash_t)siphash13(
_le64toh(_Py_HashSecret.siphash.k0), _le64toh(_Py_HashSecret.siphash.k1),
src, src_sz);
}
static PyHash_FuncDef PyHash_Func = {pysiphash, "siphash13", 64, 128};
#endif
#if Py_HASH_ALGORITHM == Py_HASH_SIPHASH24
static Py_hash_t
pysiphash(const void *src, Py_ssize_t src_sz) {