85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
// Code taken from https://github.com/floodyberry/siphash with some edits.
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//
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// To the extent possible under law, the author(s) have dedicated all copyright
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// and related and neighboring rights to this software to the public domain
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// worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication along
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// with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
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inline static uint64_t
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u8to64_le (const unsigned char *p)
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{
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return
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(uint64_t) p[0] |
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(uint64_t) p[1] << 8 |
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(uint64_t) p[2] << 16 |
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(uint64_t) p[3] << 24 |
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(uint64_t) p[4] << 32 |
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(uint64_t) p[5] << 40 |
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(uint64_t) p[6] << 48 |
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(uint64_t) p[7] << 56 ;
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}
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static uint64_t
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siphash (const unsigned char key[16], const unsigned char *m, size_t len)
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{
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uint64_t v0, v1, v2, v3;
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uint64_t mi, k0, k1;
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uint64_t last7;
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size_t i, blocks;
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k0 = u8to64_le (key + 0);
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k1 = u8to64_le (key + 8);
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v0 = k0 ^ 0x736f6d6570736575ull;
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v1 = k1 ^ 0x646f72616e646f6dull;
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v2 = k0 ^ 0x6c7967656e657261ull;
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v3 = k1 ^ 0x7465646279746573ull;
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last7 = (uint64_t) (len & 0xff) << 56;
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#define ROTL64(a,b) (((a)<<(b))|((a)>>(64-b)))
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#define COMPRESS \
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v0 += v1; v2 += v3; \
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v1 = ROTL64 (v1,13); v3 = ROTL64 (v3,16); \
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v1 ^= v0; v3 ^= v2; \
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v0 = ROTL64 (v0,32); \
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v2 += v1; v0 += v3; \
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v1 = ROTL64 (v1,17); v3 = ROTL64 (v3,21); \
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v1 ^= v2; v3 ^= v0; \
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v2 = ROTL64(v2,32);
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for (i = 0, blocks = (len & ~(size_t) 7); i < blocks; i += 8)
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{
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mi = u8to64_le (m + i);
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v3 ^= mi;
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COMPRESS
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COMPRESS
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v0 ^= mi;
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}
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switch (len - blocks)
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{
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case 7: last7 |= (uint64_t) m[i + 6] << 48; // Fall-through
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case 6: last7 |= (uint64_t) m[i + 5] << 40; // Fall-through
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case 5: last7 |= (uint64_t) m[i + 4] << 32; // Fall-through
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case 4: last7 |= (uint64_t) m[i + 3] << 24; // Fall-through
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case 3: last7 |= (uint64_t) m[i + 2] << 16; // Fall-through
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case 2: last7 |= (uint64_t) m[i + 1] << 8; // Fall-through
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case 1: last7 |= (uint64_t) m[i + 0] ; // Fall-through
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default:;
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};
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v3 ^= last7;
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COMPRESS
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COMPRESS
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v0 ^= last7;
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v2 ^= 0xff;
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COMPRESS
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COMPRESS
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COMPRESS
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COMPRESS
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return v0 ^ v1 ^ v2 ^ v3;
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}
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