From e73aaae2fa9024832e1f42e30c787c7baf61d014 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Sat, 7 May 2022 14:03:46 +0200 Subject: siphash: use one source of truth for siphash permutations The SipHash family of permutations is currently used in three places: - siphash.c itself, used in the ordinary way it was intended. - random32.c, in a construction from an anonymous contributor. - random.c, as part of its fast_mix function. Each one of these places reinvents the wheel with the same C code, same rotation constants, and same symmetry-breaking constants. This commit tidies things up a bit by placing macros for the permutations and constants into siphash.h, where each of the three .c users can access them. It also leaves a note dissuading more users of them from emerging. Signed-off-by: Jason A. Donenfeld --- lib/siphash.c | 32 ++++++++++---------------------- 1 file changed, 10 insertions(+), 22 deletions(-) (limited to 'lib/siphash.c') diff --git a/lib/siphash.c b/lib/siphash.c index 72b9068ab57b..71d315a6ad62 100644 --- a/lib/siphash.c +++ b/lib/siphash.c @@ -18,19 +18,13 @@ #include #endif -#define SIPROUND \ - do { \ - v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \ - v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \ - v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \ - v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \ - } while (0) +#define SIPROUND SIPHASH_PERMUTATION(v0, v1, v2, v3) #define PREAMBLE(len) \ - u64 v0 = 0x736f6d6570736575ULL; \ - u64 v1 = 0x646f72616e646f6dULL; \ - u64 v2 = 0x6c7967656e657261ULL; \ - u64 v3 = 0x7465646279746573ULL; \ + u64 v0 = SIPHASH_CONST_0; \ + u64 v1 = SIPHASH_CONST_1; \ + u64 v2 = SIPHASH_CONST_2; \ + u64 v3 = SIPHASH_CONST_3; \ u64 b = ((u64)(len)) << 56; \ v3 ^= key->key[1]; \ v2 ^= key->key[0]; \ @@ -389,19 +383,13 @@ u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third, } EXPORT_SYMBOL(hsiphash_4u32); #else -#define HSIPROUND \ - do { \ - v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \ - v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \ - v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \ - v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \ - } while (0) +#define HSIPROUND HSIPHASH_PERMUTATION(v0, v1, v2, v3) #define HPREAMBLE(len) \ - u32 v0 = 0; \ - u32 v1 = 0; \ - u32 v2 = 0x6c796765U; \ - u32 v3 = 0x74656462U; \ + u32 v0 = HSIPHASH_CONST_0; \ + u32 v1 = HSIPHASH_CONST_1; \ + u32 v2 = HSIPHASH_CONST_2; \ + u32 v3 = HSIPHASH_CONST_3; \ u32 b = ((u32)(len)) << 24; \ v3 ^= key->key[1]; \ v2 ^= key->key[0]; \ -- cgit v1.2.3-58-ga151