143 lines
4.6 KiB
C
143 lines
4.6 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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// modified for simplicity
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#include <stddef.h>
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#include <stdint.h>
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/* default: SipHash-2-4 */
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#ifndef cROUNDS
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#define cROUNDS 2
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#endif
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#ifndef dROUNDS
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#define dROUNDS 4
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#endif
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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_SIPHASH
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#include <stdio.h>
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#define TRACE \
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do { \
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printf("(%3zu) v0 %08" PRIx32 "\n", inlen, v0); \
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printf("(%3zu) v1 %08" PRIx32 "\n", inlen, v1); \
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printf("(%3zu) v2 %08" PRIx32 "\n", inlen, v2); \
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printf("(%3zu) v3 %08" PRIx32 "\n", 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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/*
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Computes a SipHash value
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*in: pointer to input data (read-only)
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inlen: input data length in bytes (any size_t value)
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*k: pointer to the key data (read-only), must be 8 bytes
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*out: pointer to output data (write-only), outlen bytes must be allocated
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outlen: length of the output in bytes, must be 4 or 8
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*/
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static uint32_t halfsiphash(const void *in, const size_t inlen, uint64_t k) {
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const unsigned char *ni = (const unsigned char *)in;
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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 = k;
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uint32_t k1 = k >> 32;
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uint32_t m;
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int i;
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const unsigned char *end = ni + 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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for (; ni != end; ni += 4) {
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m = U8TO32_LE(ni);
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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)ni[2]) << 16;
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/* FALLTHRU */
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case 2:
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b |= ((uint32_t)ni[1]) << 8;
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/* FALLTHRU */
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case 1:
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b |= ((uint32_t)ni[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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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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return b;
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}
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