147 lines
4.5 KiB
C
147 lines
4.5 KiB
C
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/*
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SipHash reference C implementation
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Copyright (c) 2016 Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
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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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You should have received a copy of the CC0 Public Domain Dedication along
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with
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this software. If not, see
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<http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include <assert.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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/* default: SipHash-2-4 */
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#define cROUNDS 2
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#define dROUNDS 4
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#define ROTL(x, b) (uint32_t)(((x) << (b)) | ((x) >> (32 - (b))))
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#define U32TO8_LE(p, v) \
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(p)[0] = (uint8_t)((v)); \
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(p)[1] = (uint8_t)((v) >> 8); \
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(p)[2] = (uint8_t)((v) >> 16); \
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(p)[3] = (uint8_t)((v) >> 24);
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#define U8TO32_LE(p) \
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(((uint32_t)((p)[0])) | ((uint32_t)((p)[1]) << 8) | \
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((uint32_t)((p)[2]) << 16) | ((uint32_t)((p)[3]) << 24))
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#define SIPROUND \
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do { \
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v0 += v1; \
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v1 = ROTL(v1, 5); \
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v1 ^= v0; \
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v0 = ROTL(v0, 16); \
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v2 += v3; \
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v3 = ROTL(v3, 8); \
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v3 ^= v2; \
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v0 += v3; \
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v3 = ROTL(v3, 7); \
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v3 ^= v0; \
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v2 += v1; \
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v1 = ROTL(v1, 13); \
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v1 ^= v2; \
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v2 = ROTL(v2, 16); \
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} while (0)
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#ifdef DEBUG
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#define TRACE \
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do { \
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printf("(%3d) v0 %08x\n", (int)inlen, v0); \
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printf("(%3d) v1 %08x\n", (int)inlen, v1); \
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printf("(%3d) v2 %08x\n", (int)inlen, v2); \
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printf("(%3d) v3 %08x\n", (int)inlen, v3); \
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} while (0)
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#else
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#define TRACE
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#endif
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int halfsiphash(const uint8_t *in, const size_t inlen, const uint8_t *k,
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uint8_t *out, const size_t outlen) {
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assert((outlen == 4) || (outlen == 8));
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uint32_t v0 = 0;
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uint32_t v1 = 0;
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uint32_t v2 = UINT32_C(0x6c796765);
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uint32_t v3 = UINT32_C(0x74656462);
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uint32_t k0 = U8TO32_LE(k);
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uint32_t k1 = U8TO32_LE(k + 4);
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uint32_t m;
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int i;
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const uint8_t *end = in + inlen - (inlen % sizeof(uint32_t));
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const int left = inlen & 3;
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uint32_t b = ((uint32_t)inlen) << 24;
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v3 ^= k1;
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v2 ^= k0;
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v1 ^= k1;
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v0 ^= k0;
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if (outlen == 8)
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v1 ^= 0xee;
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for (; in != end; in += 4) {
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m = U8TO32_LE(in);
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v3 ^= m;
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TRACE;
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for (i = 0; i < cROUNDS; ++i)
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SIPROUND;
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v0 ^= m;
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}
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switch (left) {
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case 3:
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b |= ((uint32_t)in[2]) << 16;
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case 2:
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b |= ((uint32_t)in[1]) << 8;
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case 1:
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b |= ((uint32_t)in[0]);
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break;
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case 0:
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break;
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}
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v3 ^= b;
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TRACE;
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for (i = 0; i < cROUNDS; ++i)
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SIPROUND;
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v0 ^= b;
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if (outlen == 8)
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v2 ^= 0xee;
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else
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v2 ^= 0xff;
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TRACE;
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for (i = 0; i < dROUNDS; ++i)
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SIPROUND;
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b = v1 ^ v3;
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U32TO8_LE(out, b);
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if (outlen == 4)
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return 0;
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v1 ^= 0xdd;
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TRACE;
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for (i = 0; i < dROUNDS; ++i)
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SIPROUND;
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b = v1 ^ v3;
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U32TO8_LE(out + 4, b);
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return 0;
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}
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