ccan

Browse Source Download (without any required ccan dependencies)

Module:

siphash

Summary:

a keyed hash function

Dependencies:

ccan/endian

Description:

SipHash-c-d, where `c` is the number of rounds per message chunk

             and `d` the number of finalization rounds,

"is a family of pseudorandom functions optimized for speed on short messages"

Implemented from the paper https://131002.net/siphash/ The designers recommend using SipHash-2-4 or SipHash-4-8

SipHash-c-d uses a 16-byte key. To defend against hash-flooding, the application needs to use a new random key regularly.

The designers of SipHash claim it is cryptographically strong to use as MAC with secret key but _not_collision_resistant_.

Returns one 64-bit word as the hash function result.

Example:

// Outputs "cf2794e0277187b7"
#include <stdio.h>
#include <ccan/siphash/siphash.h>

int main(void)
{
        unsigned char t_key[16] =
                {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
        unsigned char data[4] = "\0\1\2\3";
        uint64_t hash = siphash_2_4(data, sizeof(data), t_key);
        printf("%llx\n", (unsigned long long)hash);

        return 0;
}

License: