88 lines
1.9 KiB
Markdown
88 lines
1.9 KiB
Markdown
SipHash
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=======
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Reference implementation of SipHash, a family of pseudorandom functions
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optimized for speed on short messages.
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SipHash was designed as a mitigation to [hash-flooding DoS
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attacks](https://131002.net/siphash/siphashdos_29c3_slides.pdf).
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It is now used in the hash tables implementation of Python, Ruby, Perl
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5, etc.
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SipHash was designed by [Jean-Philippe Aumasson](https://131002.net) and
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[Daniel J. Bernstein](http://cr.yp.to).
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Usage
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-----
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Running
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```sh
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make
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```
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will build sanity checks (test vectors) for SipHash-2-4, the default
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version of SipHash:
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```C
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./siphash24_test
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```
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verifies 64 test vectors, and
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```C
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./siphash24_debug
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```
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does the same and prints intermediate values.
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The code can be adapted to implement SipHash-*c*-*d*, the version of SipHash
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with *c* compression rounds and *d* finalization rounds, by tweaking the
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lines
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```C
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#define cROUNDS 2
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#define dROUNDS 4
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```
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Obviously, if the number of rounds is modified then the test vectors
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won't verify.
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128-bit tags (experimental)
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---------------------------
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In addition to the original SipHash, which returns 64-bit tags, this
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reference code implements an experimental mode to return 128-bit tags.
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This mode is enabled when the constant `DOUBLE` is defined.
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Running
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```sh
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make double
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```
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will build `siphash24_test_double` and `siphash24_debug_double`.
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The **128-bit mode is experimental**, use at your own risk.
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Intellectual property
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---------------------
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The SipHash reference code is released under [CC0
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license](https://creativecommons.org/publicdomain/zero/1.0/), a public
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domain-like licence.
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We aren't aware of any patents or patent applications relevant to
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SipHash, and we aren't planning to apply for any.
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References
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----------
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The [SipHash page](https://131002.net/siphash) includes
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* a list of third-party implementations and modules
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* a list of projects using SipHash
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* references to cryptanalysis results
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