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#ifndef CCAN_SIPHASH_H_
#define CCAN_SIPHASH_H_
/* Licensed under GPL v2+ - see LICENSE file for details */
/* Written in 2013 by Ulrik Sverdrup */
#include <stdint.h>
#include <stddef.h>
/**
* siphash - a keyed hash function
*
* 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;
* }
*
*/
uint64_t siphash_2_4(const void *in, size_t len, const unsigned char key[16]);
#endif /* CCAN_SIPHASH_H_ */
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