siphash.h

   1 /* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
   2  *
   3  * This file is provided under a dual BSD/GPLv2 license.
   4  *
   5  * SipHash: a fast short-input PRF
   6  * https://131002.net/siphash/
   7  *
   8  * This implementation is specifically for SipHash2-4 for a secure PRF
   9  * and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
  10  * hashtables.
  11  */
  12
  13 #ifndef _LINUX_SIPHASH_H
  14 #define _LINUX_SIPHASH_H
  15
  16 #include <stdint.h>
  17 #include <stdlib.h>
  18 #include <stdbool.h>
  19 #include <libubox/utils.h>
  20
  21 #define SIPHASH_ALIGNMENT __alignof__(uint64_t)
  22 typedef struct {
  23         uint64_t key[2];
  24 } siphash_key_t;
  25
  26 static inline uint16_t get_unaligned_le16(const uint8_t *p)
  27 {
  28         return p[0] | p[1] << 8;
  29 }
  30
  31 static inline uint32_t get_unaligned_le32(const uint8_t *p)
  32 {
  33         return p[0] | p[1] << 8 | p[2] << 16 | p[3] << 24;
  34 }
  35
  36 static inline uint64_t get_unaligned_le64(const uint8_t *p)
  37 {
  38         return (uint64_t)get_unaligned_le32(p + 4) << 32 |
  39                get_unaligned_le32(p);
  40 }
  41
  42 static inline bool siphash_key_is_zero(const siphash_key_t *key)
  43 {
  44         return !(key->key[0] | key->key[1]);
  45 }
  46
  47 uint64_t siphash(const void *data, size_t len, const siphash_key_t *key);
  48
  49 static inline void siphash_to_le64(void *dest, const void *data, size_t len,
  50                                    const siphash_key_t *key)
  51 {
  52         uint64_t hash = siphash(data, len, key);
  53
  54         *(uint64_t *)dest = cpu_to_le64(hash);
  55 }
  56
  57 #endif /* _LINUX_SIPHASH_H */