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/* $OpenBSD: siphash.c,v 1.4 2017/04/12 18:35:50 florian Exp $ */
/*-
* Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d
* are the number of compression rounds and the number of finalization rounds.
* A compression round is identical to a finalization round and this round
* function is called SipRound. Given a 128-bit key k and a (possibly empty)
* byte string m, SipHash-c-d returns a 64-bit value SipHash-c-d(k; m).
*
* Implemented from the paper "SipHash: a fast short-input PRF", 2012.09.18,
* by Jean-Philippe Aumasson and Daniel J. Bernstein,
* Permanent Document ID b9a943a805fbfc6fde808af9fc0ecdfa
* https://131002.net/siphash/siphash.pdf
* https://131002.net/siphash/
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <crypto/siphash.h>
static void SipHash_CRounds(SIPHASH_CTX *, int);
static void SipHash_Rounds(SIPHASH_CTX *, int);
void
SipHash_Init(SIPHASH_CTX *ctx, const SIPHASH_KEY *key)
{
uint64_t k0, k1;
k0 = lemtoh64(&key->k0);
k1 = lemtoh64(&key->k1);
ctx->v[0] = 0x736f6d6570736575ULL ^ k0;
ctx->v[1] = 0x646f72616e646f6dULL ^ k1;
ctx->v[2] = 0x6c7967656e657261ULL ^ k0;
ctx->v[3] = 0x7465646279746573ULL ^ k1;
memset(ctx->buf, 0, sizeof(ctx->buf));
ctx->bytes = 0;
}
void
SipHash_Update(SIPHASH_CTX *ctx, int rc, int rf, const void *src, size_t len)
{
const uint8_t *ptr = src;
size_t left, used;
if (len == 0)
return;
used = ctx->bytes % sizeof(ctx->buf);
ctx->bytes += len;
if (used > 0) {
left = sizeof(ctx->buf) - used;
if (len >= left) {
memcpy(&ctx->buf[used], ptr, left);
SipHash_CRounds(ctx, rc);
len -= left;
ptr += left;
} else {
memcpy(&ctx->buf[used], ptr, len);
return;
}
}
while (len >= sizeof(ctx->buf)) {
memcpy(ctx->buf, ptr, sizeof(ctx->buf));
SipHash_CRounds(ctx, rc);
len -= sizeof(ctx->buf);
ptr += sizeof(ctx->buf);
}
if (len > 0)
memcpy(&ctx->buf[used], ptr, len);
}
void
SipHash_Final(void *dst, SIPHASH_CTX *ctx, int rc, int rf)
{
uint64_t r;
htolem64(&r, SipHash_End(ctx, rc, rf));
memcpy(dst, &r, sizeof r);
}
uint64_t
SipHash_End(SIPHASH_CTX *ctx, int rc, int rf)
{
uint64_t r;
size_t left, used;
used = ctx->bytes % sizeof(ctx->buf);
left = sizeof(ctx->buf) - used;
memset(&ctx->buf[used], 0, left - 1);
ctx->buf[7] = ctx->bytes;
SipHash_CRounds(ctx, rc);
ctx->v[2] ^= 0xff;
SipHash_Rounds(ctx, rf);
r = (ctx->v[0] ^ ctx->v[1]) ^ (ctx->v[2] ^ ctx->v[3]);
explicit_bzero(ctx, sizeof(*ctx));
return (r);
}
uint64_t
SipHash(const SIPHASH_KEY *key, int rc, int rf, const void *src, size_t len)
{
SIPHASH_CTX ctx;
SipHash_Init(&ctx, key);
SipHash_Update(&ctx, rc, rf, src, len);
return (SipHash_End(&ctx, rc, rf));
}
#define SIP_ROTL(x, b) ((x) << (b)) | ( (x) >> (64 - (b)))
static void
SipHash_Rounds(SIPHASH_CTX *ctx, int rounds)
{
while (rounds--) {
ctx->v[0] += ctx->v[1];
ctx->v[2] += ctx->v[3];
ctx->v[1] = SIP_ROTL(ctx->v[1], 13);
ctx->v[3] = SIP_ROTL(ctx->v[3], 16);
ctx->v[1] ^= ctx->v[0];
ctx->v[3] ^= ctx->v[2];
ctx->v[0] = SIP_ROTL(ctx->v[0], 32);
ctx->v[2] += ctx->v[1];
ctx->v[0] += ctx->v[3];
ctx->v[1] = SIP_ROTL(ctx->v[1], 17);
ctx->v[3] = SIP_ROTL(ctx->v[3], 21);
ctx->v[1] ^= ctx->v[2];
ctx->v[3] ^= ctx->v[0];
ctx->v[2] = SIP_ROTL(ctx->v[2], 32);
}
}
static void
SipHash_CRounds(SIPHASH_CTX *ctx, int rounds)
{
uint64_t m = lemtoh64((uint64_t *)ctx->buf);
ctx->v[3] ^= m;
SipHash_Rounds(ctx, rounds);
ctx->v[0] ^= m;
}
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