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hash function) optimized for speed on short messages returning a 64bit hash/ digest value. SipHash is simpler and much faster than other secure MACs and competitive in speed with popular non-cryptographic hash functions. It uses a 128-bit key without the hidden cost of a key expansion step. SipHash iterates a simple round function consisting of four additions, four xors, and six rotations, interleaved with xors of message blocks for a pre-defined number of compression and finalization rounds. The absence of secret load/store addresses or secret branch conditions avoid timing attacks. No state is shared between messages. Hashing is deterministic and doesn't use nonces. It is not susceptible to length extension attacks. Target applications include network traffic authentication, message authentication (MAC) and hash-tables protection against hash-flooding denial-of-service attacks. The number of update/finalization rounds is defined during initialization: SipHash24_Init() for the fast and reasonable strong version. SipHash48_Init() for the strong version (half as fast). SipHash usage is similar to other hash functions: struct SIPHASH_CTX ctx; char *k = "16bytes long key" char *s = "string"; uint64_t h = 0; SipHash24_Init(&ctx); SipHash_SetKey(&ctx, k); SipHash_Update(&ctx, s, strlen(s)); SipHash_Final(&h, &ctx); /* or */ h = SipHash_End(&ctx); /* or */ h = SipHash24(&ctx, k, s, strlen(s)); It was designed by Jean-Philippe Aumasson and Daniel J. Bernstein and is described in the paper "SipHash: a fast short-input PRF", 2012.09.18: https://131002.net/siphash/siphash.pdf Permanent ID: b9a943a805fbfc6fde808af9fc0ecdfa Implemented by: andre (based on the paper) Reviewed by: cperciva
84 lines
3.0 KiB
C
84 lines
3.0 KiB
C
/*-
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* Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* SipHash is a family of pseudorandom functions (a.k.a. keyed hash functions)
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* optimized for speed on short messages returning a 64bit hash/digest value.
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*
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* The number of rounds is defined during the initialization:
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* SipHash24_Init() for the fast and resonable strong version
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* SipHash48_Init() for the strong version (half as fast)
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*
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* struct SIPHASH_CTX ctx;
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* SipHash24_Init(&ctx);
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* SipHash_SetKey(&ctx, "16bytes long key");
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* SipHash_Update(&ctx, pointer_to_string, length_of_string);
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* SipHash_Final(output, &ctx);
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*/
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#ifndef _SIPHASH_H_
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#define _SIPHASH_H_
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#define SIPHASH_BLOCK_LENGTH 8
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#define SIPHASH_KEY_LENGTH 16
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#define SIPHASH_DIGEST_LENGTH 8
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typedef struct _SIPHASH_CTX {
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uint64_t v[4];
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union {
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uint64_t b64;
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uint8_t b8[8];
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} buf;
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uint64_t bytes;
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uint8_t buflen;
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uint8_t rounds_compr;
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uint8_t rounds_final;
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uint8_t initialized;
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} SIPHASH_CTX;
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#define SipHash24_Init(x) SipHash_InitX((x), 2, 4)
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#define SipHash48_Init(x) SipHash_InitX((x), 4, 8)
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void SipHash_InitX(SIPHASH_CTX *, int, int);
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void SipHash_SetKey(SIPHASH_CTX *, const uint8_t [16]);
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void SipHash_Update(SIPHASH_CTX *, const void *, size_t);
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void SipHash_Final(void *, SIPHASH_CTX *);
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uint64_t SipHash_End(SIPHASH_CTX *);
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#define SipHash24(x, y, z, i) SipHashX((x), 2, 4, (y), (z), (i));
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#define SipHash48(x, y, z, i) SipHashX((x), 4, 8, (y), (z), (i));
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uint64_t SipHashX(SIPHASH_CTX *, int, int, const uint8_t [16], const void *,
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size_t);
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int SipHash24_TestVectors(void);
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#endif /* _SIPHASH_H_ */
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