--- /dev/null
+/*
+ SipHash reference C implementation
+
+ Copyright (c) 2012-2016 Jean-Philippe Aumasson
+ <jeanphilippe.aumasson@gmail.com>
+ Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
+
+ To the extent possible under law, the author(s) have dedicated all copyright
+ and related and neighboring rights to this software to the public domain
+ worldwide. This software is distributed without any warranty.
+
+ You should have received a copy of the CC0 Public Domain Dedication along
+ with
+ this software. If not, see
+ <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+/* default: SipHash-2-4 */
+#define cROUNDS 2
+#define dROUNDS 4
+
+#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
+
+#define U32TO8_LE(p, v) \
+ (p)[0] = (uint8_t)((v)); \
+ (p)[1] = (uint8_t)((v) >> 8); \
+ (p)[2] = (uint8_t)((v) >> 16); \
+ (p)[3] = (uint8_t)((v) >> 24);
+
+#define U64TO8_LE(p, v) \
+ U32TO8_LE((p), (uint32_t)((v))); \
+ U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
+
+#define U8TO64_LE(p) \
+ (((uint64_t)((p)[0])) | ((uint64_t)((p)[1]) << 8) | \
+ ((uint64_t)((p)[2]) << 16) | ((uint64_t)((p)[3]) << 24) | \
+ ((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40) | \
+ ((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
+
+#define SIPROUND \
+ do { \
+ v0 += v1; \
+ v1 = ROTL(v1, 13); \
+ v1 ^= v0; \
+ v0 = ROTL(v0, 32); \
+ v2 += v3; \
+ v3 = ROTL(v3, 16); \
+ v3 ^= v2; \
+ v0 += v3; \
+ v3 = ROTL(v3, 21); \
+ v3 ^= v0; \
+ v2 += v1; \
+ v1 = ROTL(v1, 17); \
+ v1 ^= v2; \
+ v2 = ROTL(v2, 32); \
+ } while (0)
+
+#ifdef DEBUG
+#define TRACE \
+ do { \
+ printf("(%3d) v0 %08x %08x\n", (int)inlen, (uint32_t)(v0 >> 32), \
+ (uint32_t)v0); \
+ printf("(%3d) v1 %08x %08x\n", (int)inlen, (uint32_t)(v1 >> 32), \
+ (uint32_t)v1); \
+ printf("(%3d) v2 %08x %08x\n", (int)inlen, (uint32_t)(v2 >> 32), \
+ (uint32_t)v2); \
+ printf("(%3d) v3 %08x %08x\n", (int)inlen, (uint32_t)(v3 >> 32), \
+ (uint32_t)v3); \
+ } while (0)
+#else
+#define TRACE
+#endif
+
+int siphash(const uint8_t *in, const size_t inlen, const uint8_t *k,
+ uint8_t *out, const size_t outlen) {
+ uint64_t v0 = 0x736f6d6570736575ULL;
+ uint64_t v1 = 0x646f72616e646f6dULL;
+ uint64_t v2 = 0x6c7967656e657261ULL;
+ uint64_t v3 = 0x7465646279746573ULL;
+ uint64_t k0 = U8TO64_LE(k);
+ uint64_t k1 = U8TO64_LE(k + 8);
+ uint64_t m;
+ int i;
+ const uint8_t *end = in + inlen - (inlen % sizeof(uint64_t));
+ const int left = inlen & 7;
+ uint64_t b = ((uint64_t)inlen) << 56;
+ v3 ^= k1;
+ v2 ^= k0;
+ v1 ^= k1;
+ v0 ^= k0;
+
+ assert((outlen == 8) || (outlen == 16));
+ if (outlen == 16)
+ v1 ^= 0xee;
+
+ for (; in != end; in += 8) {
+ m = U8TO64_LE(in);
+ v3 ^= m;
+
+ TRACE;
+ for (i = 0; i < cROUNDS; ++i)
+ SIPROUND;
+
+ v0 ^= m;
+ }
+
+ switch (left) {
+ case 7:
+ b |= ((uint64_t)in[6]) << 48;
+ /* fallthrough */
+ case 6:
+ b |= ((uint64_t)in[5]) << 40;
+ /* fallthrough */
+ case 5:
+ b |= ((uint64_t)in[4]) << 32;
+ /* fallthrough */
+ case 4:
+ b |= ((uint64_t)in[3]) << 24;
+ /* fallthrough */
+ case 3:
+ b |= ((uint64_t)in[2]) << 16;
+ /* fallthrough */
+ case 2:
+ b |= ((uint64_t)in[1]) << 8;
+ /* fallthrough */
+ case 1:
+ b |= ((uint64_t)in[0]);
+ break;
+ case 0:
+ break;
+ }
+
+ v3 ^= b;
+
+ TRACE;
+ for (i = 0; i < cROUNDS; ++i)
+ SIPROUND;
+
+ v0 ^= b;
+
+ if (outlen == 16)
+ v2 ^= 0xee;
+ else
+ v2 ^= 0xff;
+
+ TRACE;
+ for (i = 0; i < dROUNDS; ++i)
+ SIPROUND;
+
+ b = v0 ^ v1 ^ v2 ^ v3;
+ U64TO8_LE(out, b);
+
+ if (outlen == 8)
+ return 0;
+
+ v1 ^= 0xdd;
+
+ TRACE;
+ for (i = 0; i < dROUNDS; ++i)
+ SIPROUND;
+
+ b = v0 ^ v1 ^ v2 ^ v3;
+ U64TO8_LE(out + 8, b);
+
+ return 0;
+}