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xxh3: use combined secrets for small inputs

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to make it more difficult to retrieve information about the secret.

Note : should cost nothing for usage with "default" `kSecret`
This commit is contained in:
Yann Collet 2020-02-28 15:28:17 -08:00
parent 152d50900b
commit cd078d265d
1 changed files with 12 additions and 7 deletions
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19
xxh3.h
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@ -654,9 +654,10 @@ XXH3_len_1to3_64b(const xxh_u8* input, size_t len, const xxh_u8* secret, XXH64_h
{ xxh_u8 const c1 = input[0];
xxh_u8 const c2 = input[len >> 1];
xxh_u8 const c3 = input[len - 1];
xxh_u32 const combined = ((xxh_u32)c1<<16) | (((xxh_u32)c2) << 24) | (((xxh_u32)c3) << 0) | (((xxh_u32)len) << 8);
xxh_u64 const keyed = (xxh_u64)combined ^ (XXH_readLE32(secret) + seed);
xxh_u64 const mixed = keyed * PRIME64_1;
xxh_u32 const combined = ((xxh_u32)c1<<16) | (((xxh_u32)c2) << 24) | (((xxh_u32)c3) << 0) | (((xxh_u32)len) << 8);
xxh_u64 const bitflip = (XXH_readLE32(secret) ^ XXH_readLE32(secret+4)) + seed;
xxh_u64 const keyed = (xxh_u64)combined ^ bitflip;
xxh_u64 const mixed = keyed * PRIME64_1;
return XXH3_avalanche(mixed);
}
}
@ -670,8 +671,10 @@ XXH3_len_4to8_64b(const xxh_u8* input, size_t len, const xxh_u8* secret, XXH64_h
seed ^= (xxh_u64)XXH_swap32((xxh_u32)seed) << 32;
{ xxh_u32 const input1 = XXH_readLE32(input);
xxh_u32 const input2 = XXH_readLE32(input + len - 4);
xxh_u32 const key1 = XXH_swap32(input1) ^ ((xxh_u32)(seed >> 32) + XXH_readLE32(secret));
xxh_u32 const key2 = input2 ^ (XXH_readLE32(secret+4) - (xxh_u32)seed);
xxh_u32 const bitflip1 = (XXH_readLE32(secret+8) ^ XXH_readLE32(secret)+12) + (xxh_u32)(seed >> 32);
xxh_u32 const bitflip2 = (XXH_readLE32(secret+16) ^ XXH_readLE32(secret)+20) - (xxh_u32)seed;
xxh_u32 const key1 = XXH_swap32(input1) ^ bitflip1;
xxh_u32 const key2 = input2 ^ bitflip2;
xxh_u64 const mix = XXH_mult32to64(key1, key2)
+ ((xxh_u64)input1 << 32)
+ ((xxh_u64)(XXH_rotl32(input2,23)) << 32)
@ -686,8 +689,10 @@ XXH3_len_9to16_64b(const xxh_u8* input, size_t len, const xxh_u8* secret, XXH64_
XXH_ASSERT(input != NULL);
XXH_ASSERT(secret != NULL);
XXH_ASSERT(8 <= len && len <= 16);
{ xxh_u64 const input_lo = XXH_readLE64(input) ^ XXH_readLE64(secret);
xxh_u64 const input_hi = XXH_readLE64(input + len - 8) ^ (XXH_readLE64(secret + 8) - seed);
{ xxh_u64 const bitflip1 = (XXH_readLE64(secret+16) ^ XXH_readLE64(secret+24)) + seed;
xxh_u64 const bitflip2 = (XXH_readLE64(secret+32) ^ XXH_readLE64(secret+40)) - seed;
xxh_u64 const input_lo = XXH_readLE64(input) ^ bitflip1;
xxh_u64 const input_hi = XXH_readLE64(input + len - 8) ^ bitflip2;
xxh_u64 const acc = len
+ XXH_swap64(input_lo) + input_hi
+ XXH3_mul128_fold64(input_lo, input_hi);