80 lines
1.9 KiB
Markdown
80 lines
1.9 KiB
Markdown
# SipHash
|
|
|
|
Reference implementation of SipHash, a family of pseudorandom functions
|
|
optimized for speed on short messages.
|
|
|
|
SipHash was designed as a mitigation to [hash-flooding DoS
|
|
attacks](https://131002.net/siphash/siphashdos_29c3_slides.pdf).
|
|
It is now used in the hash tables implementation of Python, Ruby, Perl
|
|
5, etc.
|
|
|
|
SipHash was designed by [Jean-Philippe Aumasson](https://131002.net) and
|
|
[Daniel J. Bernstein](http://cr.yp.to).
|
|
|
|
|
|
## Usage
|
|
|
|
Running
|
|
|
|
```sh
|
|
make
|
|
```
|
|
|
|
will build tests for
|
|
|
|
* SipHash-2-4, the default version of SipHash returning 64-bit tags
|
|
* SipHash-2-4 with doubled tag size, i.e. 128-bit tags
|
|
* HalfSipHash-2-4, a version of SipHash working with 32-bit words and
|
|
returning 32-bit tags by default
|
|
* HalfSipHash-2-4 with doubled tag size, i.e. 64-bit tags
|
|
|
|
|
|
```C
|
|
./test
|
|
```
|
|
|
|
verifies 64 test vectors, and
|
|
|
|
```C
|
|
./debug
|
|
```
|
|
|
|
does the same and prints intermediate values.
|
|
|
|
The code can be adapted to implement SipHash-*c*-*d*, the version of SipHash
|
|
with *c* compression rounds and *d* finalization rounds, by defining `cROUNDS`
|
|
or `dROUNDS` when compiling. This can be done with `-D` command line arguments
|
|
to many compilers such as below.
|
|
|
|
```sh
|
|
gcc -Wall --std=c99 -DcROUNDS=2 -DdROUNDS=4 siphash.c halfsiphash.c test.c -o test
|
|
```
|
|
|
|
The `makefile` also takes *c* and *d* rounds values as parameters.
|
|
|
|
```sh
|
|
make cROUNDS=2 dROUNDS=4
|
|
```
|
|
|
|
Obviously, if the number of rounds is modified then the test vectors
|
|
won't verify.
|
|
|
|
|
|
|
|
## Intellectual property
|
|
|
|
The SipHash reference code is released under [CC0
|
|
license](https://creativecommons.org/publicdomain/zero/1.0/), a public
|
|
domain-like licence.
|
|
|
|
We aren't aware of any patents or patent applications relevant to
|
|
SipHash, and we aren't planning to apply for any.
|
|
|
|
|
|
## References
|
|
|
|
The [SipHash page](https://131002.net/siphash) includes
|
|
* a list of third-party implementations and modules
|
|
* a list of projects using SipHash
|
|
* references to cryptanalysis results
|