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linux/lib/siphash.c
Jason A. Donenfeld 1ae2324f73 siphash: implement HalfSipHash1-3 for hash tables 
HalfSipHash, or hsiphash, is a shortened version of SipHash, which
generates 32-bit outputs using a weaker 64-bit key. It has *much* lower
security margins, and shouldn't be used for anything too sensitive, but
it could be used as a hashtable key function replacement, if the output
is never exposed, and if the security requirement is not too high.

The goal is to make this something that performance-critical jhash users
would be willing to use.

On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias
SipHash1-3 to HalfSipHash1-3 on those systems.

64-bit x86_64:
[    0.509409] test_siphash:     SipHash2-4 cycles: 4049181
[    0.510650] test_siphash:     SipHash1-3 cycles: 2512884
[    0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920
[    0.512904] test_siphash:    JenkinsHash cycles:  978267
So, we map hsiphash() -> SipHash1-3

32-bit x86:
[    0.509868] test_siphash:     SipHash2-4 cycles: 14812892
[    0.513601] test_siphash:     SipHash1-3 cycles:  9510710
[    0.515263] test_siphash: HalfSipHash1-3 cycles:  3856157
[    0.515952] test_siphash:    JenkinsHash cycles:  1148567
So, we map hsiphash() -> HalfSipHash1-3

hsiphash() is roughly 3 times slower than jhash(), but comes with a
considerable security improvement.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-09 13:58:57 -05:00

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/* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*
* This file is provided under a dual BSD/GPLv2 license.
*
* SipHash: a fast short-input PRF
* https://131002.net/siphash/
*
* This implementation is specifically for SipHash2-4 for a secure PRF
* and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
* hashtables.
*/
#include <linux/siphash.h>
#include <asm/unaligned.h>
#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
#include <linux/dcache.h>
#include <asm/word-at-a-time.h>
#endif
#define SIPROUND \
do { \
v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \
v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \
v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \
v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \
} while (0)
#define PREAMBLE(len) \
u64 v0 = 0x736f6d6570736575ULL; \
u64 v1 = 0x646f72616e646f6dULL; \
u64 v2 = 0x6c7967656e657261ULL; \
u64 v3 = 0x7465646279746573ULL; \
u64 b = ((u64)(len)) << 56; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \
v1 ^= key->key[1]; \
v0 ^= key->key[0];
#define POSTAMBLE \
v3 ^= b; \
SIPROUND; \
SIPROUND; \
v0 ^= b; \
v2 ^= 0xff; \
SIPROUND; \
SIPROUND; \
SIPROUND; \
SIPROUND; \
return (v0 ^ v1) ^ (v2 ^ v3);
u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u64));
const u8 left = len & (sizeof(u64) - 1);
u64 m;
PREAMBLE(len)
for (; data != end; data += sizeof(u64)) {
m = le64_to_cpup(data);
v3 ^= m;
SIPROUND;
SIPROUND;
v0 ^= m;
}
#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
if (left)
b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
bytemask_from_count(left)));
#else
switch (left) {
case 7: b |= ((u64)end[6]) << 48;
case 6: b |= ((u64)end[5]) << 40;
case 5: b |= ((u64)end[4]) << 32;
case 4: b |= le32_to_cpup(data); break;
case 3: b |= ((u64)end[2]) << 16;
case 2: b |= le16_to_cpup(data); break;
case 1: b |= end[0];
}
#endif
POSTAMBLE
}
EXPORT_SYMBOL(__siphash_aligned);
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u64));
const u8 left = len & (sizeof(u64) - 1);
u64 m;
PREAMBLE(len)
for (; data != end; data += sizeof(u64)) {
m = get_unaligned_le64(data);
v3 ^= m;
SIPROUND;
SIPROUND;
v0 ^= m;
}
#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
if (left)
b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
bytemask_from_count(left)));
#else
switch (left) {
case 7: b |= ((u64)end[6]) << 48;
case 6: b |= ((u64)end[5]) << 40;
case 5: b |= ((u64)end[4]) << 32;
case 4: b |= get_unaligned_le32(end); break;
case 3: b |= ((u64)end[2]) << 16;
case 2: b |= get_unaligned_le16(end); break;
case 1: b |= end[0];
}
#endif
POSTAMBLE
}
EXPORT_SYMBOL(__siphash_unaligned);
#endif
/**
* siphash_1u64 - compute 64-bit siphash PRF value of a u64
* @first: first u64
* @key: the siphash key
*/
u64 siphash_1u64(const u64 first, const siphash_key_t *key)
{
PREAMBLE(8)
v3 ^= first;
SIPROUND;
SIPROUND;
v0 ^= first;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_1u64);
/**
* siphash_2u64 - compute 64-bit siphash PRF value of 2 u64
* @first: first u64
* @second: second u64
* @key: the siphash key
*/
u64 siphash_2u64(const u64 first, const u64 second, const siphash_key_t *key)
{
PREAMBLE(16)
v3 ^= first;
SIPROUND;
SIPROUND;
v0 ^= first;
v3 ^= second;
SIPROUND;
SIPROUND;
v0 ^= second;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_2u64);
/**
* siphash_3u64 - compute 64-bit siphash PRF value of 3 u64
* @first: first u64
* @second: second u64
* @third: third u64
* @key: the siphash key
*/
u64 siphash_3u64(const u64 first, const u64 second, const u64 third,
const siphash_key_t *key)
{
PREAMBLE(24)
v3 ^= first;
SIPROUND;
SIPROUND;
v0 ^= first;
v3 ^= second;
SIPROUND;
SIPROUND;
v0 ^= second;
v3 ^= third;
SIPROUND;
SIPROUND;
v0 ^= third;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_3u64);
/**
* siphash_4u64 - compute 64-bit siphash PRF value of 4 u64
* @first: first u64
* @second: second u64
* @third: third u64
* @forth: forth u64
* @key: the siphash key
*/
u64 siphash_4u64(const u64 first, const u64 second, const u64 third,
const u64 forth, const siphash_key_t *key)
{
PREAMBLE(32)
v3 ^= first;
SIPROUND;
SIPROUND;
v0 ^= first;
v3 ^= second;
SIPROUND;
SIPROUND;
v0 ^= second;
v3 ^= third;
SIPROUND;
SIPROUND;
v0 ^= third;
v3 ^= forth;
SIPROUND;
SIPROUND;
v0 ^= forth;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_4u64);
u64 siphash_1u32(const u32 first, const siphash_key_t *key)
{
PREAMBLE(4)
b |= first;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_1u32);
u64 siphash_3u32(const u32 first, const u32 second, const u32 third,
const siphash_key_t *key)
{
u64 combined = (u64)second << 32 | first;
PREAMBLE(12)
v3 ^= combined;
SIPROUND;
SIPROUND;
v0 ^= combined;
b |= third;
POSTAMBLE
}
EXPORT_SYMBOL(siphash_3u32);
#if BITS_PER_LONG == 64
/* Note that on 64-bit, we make HalfSipHash1-3 actually be SipHash1-3, for
* performance reasons. On 32-bit, below, we actually implement HalfSipHash1-3.
*/
#define HSIPROUND SIPROUND
#define HPREAMBLE(len) PREAMBLE(len)
#define HPOSTAMBLE \
v3 ^= b; \
HSIPROUND; \
v0 ^= b; \
v2 ^= 0xff; \
HSIPROUND; \
HSIPROUND; \
HSIPROUND; \
return (v0 ^ v1) ^ (v2 ^ v3);
u32 __hsiphash_aligned(const void *data, size_t len, const hsiphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u64));
const u8 left = len & (sizeof(u64) - 1);
u64 m;
HPREAMBLE(len)
for (; data != end; data += sizeof(u64)) {
m = le64_to_cpup(data);
v3 ^= m;
HSIPROUND;
v0 ^= m;
}
#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
if (left)
b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
bytemask_from_count(left)));
#else
switch (left) {
case 7: b |= ((u64)end[6]) << 48;
case 6: b |= ((u64)end[5]) << 40;
case 5: b |= ((u64)end[4]) << 32;
case 4: b |= le32_to_cpup(data); break;
case 3: b |= ((u64)end[2]) << 16;
case 2: b |= le16_to_cpup(data); break;
case 1: b |= end[0];
}
#endif
HPOSTAMBLE
}
EXPORT_SYMBOL(__hsiphash_aligned);
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
u32 __hsiphash_unaligned(const void *data, size_t len,
const hsiphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u64));
const u8 left = len & (sizeof(u64) - 1);
u64 m;
HPREAMBLE(len)
for (; data != end; data += sizeof(u64)) {
m = get_unaligned_le64(data);
v3 ^= m;
HSIPROUND;
v0 ^= m;
}
#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
if (left)
b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
bytemask_from_count(left)));
#else
switch (left) {
case 7: b |= ((u64)end[6]) << 48;
case 6: b |= ((u64)end[5]) << 40;
case 5: b |= ((u64)end[4]) << 32;
case 4: b |= get_unaligned_le32(end); break;
case 3: b |= ((u64)end[2]) << 16;
case 2: b |= get_unaligned_le16(end); break;
case 1: b |= end[0];
}
#endif
HPOSTAMBLE
}
EXPORT_SYMBOL(__hsiphash_unaligned);
#endif
/**
* hsiphash_1u32 - compute 64-bit hsiphash PRF value of a u32
* @first: first u32
* @key: the hsiphash key
*/
u32 hsiphash_1u32(const u32 first, const hsiphash_key_t *key)
{
HPREAMBLE(4)
b |= first;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_1u32);
/**
* hsiphash_2u32 - compute 32-bit hsiphash PRF value of 2 u32
* @first: first u32
* @second: second u32
* @key: the hsiphash key
*/
u32 hsiphash_2u32(const u32 first, const u32 second, const hsiphash_key_t *key)
{
u64 combined = (u64)second << 32 | first;
HPREAMBLE(8)
v3 ^= combined;
HSIPROUND;
v0 ^= combined;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_2u32);
/**
* hsiphash_3u32 - compute 32-bit hsiphash PRF value of 3 u32
* @first: first u32
* @second: second u32
* @third: third u32
* @key: the hsiphash key
*/
u32 hsiphash_3u32(const u32 first, const u32 second, const u32 third,
const hsiphash_key_t *key)
{
u64 combined = (u64)second << 32 | first;
HPREAMBLE(12)
v3 ^= combined;
HSIPROUND;
v0 ^= combined;
b |= third;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_3u32);
/**
* hsiphash_4u32 - compute 32-bit hsiphash PRF value of 4 u32
* @first: first u32
* @second: second u32
* @third: third u32
* @forth: forth u32
* @key: the hsiphash key
*/
u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third,
const u32 forth, const hsiphash_key_t *key)
{
u64 combined = (u64)second << 32 | first;
HPREAMBLE(16)
v3 ^= combined;
HSIPROUND;
v0 ^= combined;
combined = (u64)forth << 32 | third;
v3 ^= combined;
HSIPROUND;
v0 ^= combined;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_4u32);
#else
#define HSIPROUND \
do { \
v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \
v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \
v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \
v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \
} while (0)
#define HPREAMBLE(len) \
u32 v0 = 0; \
u32 v1 = 0; \
u32 v2 = 0x6c796765U; \
u32 v3 = 0x74656462U; \
u32 b = ((u32)(len)) << 24; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \
v1 ^= key->key[1]; \
v0 ^= key->key[0];
#define HPOSTAMBLE \
v3 ^= b; \
HSIPROUND; \
v0 ^= b; \
v2 ^= 0xff; \
HSIPROUND; \
HSIPROUND; \
HSIPROUND; \
return v1 ^ v3;
u32 __hsiphash_aligned(const void *data, size_t len, const hsiphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u32));
const u8 left = len & (sizeof(u32) - 1);
u32 m;
HPREAMBLE(len)
for (; data != end; data += sizeof(u32)) {
m = le32_to_cpup(data);
v3 ^= m;
HSIPROUND;
v0 ^= m;
}
switch (left) {
case 3: b |= ((u32)end[2]) << 16;
case 2: b |= le16_to_cpup(data); break;
case 1: b |= end[0];
}
HPOSTAMBLE
}
EXPORT_SYMBOL(__hsiphash_aligned);
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
u32 __hsiphash_unaligned(const void *data, size_t len,
const hsiphash_key_t *key)
{
const u8 *end = data + len - (len % sizeof(u32));
const u8 left = len & (sizeof(u32) - 1);
u32 m;
HPREAMBLE(len)
for (; data != end; data += sizeof(u32)) {
m = get_unaligned_le32(data);
v3 ^= m;
HSIPROUND;
v0 ^= m;
}
switch (left) {
case 3: b |= ((u32)end[2]) << 16;
case 2: b |= get_unaligned_le16(end); break;
case 1: b |= end[0];
}
HPOSTAMBLE
}
EXPORT_SYMBOL(__hsiphash_unaligned);
#endif
/**
* hsiphash_1u32 - compute 32-bit hsiphash PRF value of a u32
* @first: first u32
* @key: the hsiphash key
*/
u32 hsiphash_1u32(const u32 first, const hsiphash_key_t *key)
{
HPREAMBLE(4)
v3 ^= first;
HSIPROUND;
v0 ^= first;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_1u32);
/**
* hsiphash_2u32 - compute 32-bit hsiphash PRF value of 2 u32
* @first: first u32
* @second: second u32
* @key: the hsiphash key
*/
u32 hsiphash_2u32(const u32 first, const u32 second, const hsiphash_key_t *key)
{
HPREAMBLE(8)
v3 ^= first;
HSIPROUND;
v0 ^= first;
v3 ^= second;
HSIPROUND;
v0 ^= second;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_2u32);
/**
* hsiphash_3u32 - compute 32-bit hsiphash PRF value of 3 u32
* @first: first u32
* @second: second u32
* @third: third u32
* @key: the hsiphash key
*/
u32 hsiphash_3u32(const u32 first, const u32 second, const u32 third,
const hsiphash_key_t *key)
{
HPREAMBLE(12)
v3 ^= first;
HSIPROUND;
v0 ^= first;
v3 ^= second;
HSIPROUND;
v0 ^= second;
v3 ^= third;
HSIPROUND;
v0 ^= third;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_3u32);
/**
* hsiphash_4u32 - compute 32-bit hsiphash PRF value of 4 u32
* @first: first u32
* @second: second u32
* @third: third u32
* @forth: forth u32
* @key: the hsiphash key
*/
u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third,
const u32 forth, const hsiphash_key_t *key)
{
HPREAMBLE(16)
v3 ^= first;
HSIPROUND;
v0 ^= first;
v3 ^= second;
HSIPROUND;
v0 ^= second;
v3 ^= third;
HSIPROUND;
v0 ^= third;
v3 ^= forth;
HSIPROUND;
v0 ^= forth;
HPOSTAMBLE
}
EXPORT_SYMBOL(hsiphash_4u32);
#endif
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