csiphash 0.0.3

A CFFI-based implementation of SipHash24

SipHash is a hash function and message authentication code that is secure, fast and simple. It accepts a 128-bit secret key and a variable-length message, and returns a 64-bit hash. It performs better than most cryptographic hash function-based MACs (especially for short inputs), and offers much better security than non-cryptographic hash functions, providing resistance against hash-flooding DoS attacks. As a result, it is now used as the hash function of choice for hash tables in Python, Ruby, Rust and Redis.

This Python package is the SipHash-2-4 C reference implementation, wrapped with CFFI. It’s incredibly fast: amortized hashing times tested as follows on a mid-2015 MacBook Pro:

Message Size	Time per Hash (Amortized over 1M)
43 bytes	4.89 microseconds
256 bytes	5.00 microseconds
1500 bytes	6.12 microseconds
1 MiB	0.88 milliseconds

Installation

You can get this library with pip:

pip install csiphash

Usage

Currently there’s just a single function, siphash24(), that accepts a secret key bytestring of length 16 and an arbitrary length bytestring for the message, and returns an 8-byte digest bytestring:

>>> from csiphash import siphash24
>>> siphash24(b'\x00' * 16, b'hello, world!\n')
b'\xf1G4\x95\xa5\xaa\xc2b'

If you want to specify keys in hexadecimal, use .decode('hex'):

>>> siphash24('abcdef01234567899876543210fedcba'.decode('hex'), b'hello, world!\n')
'\xd3\xd4N\x1dk\x1f$='

If you want digests in hexadecimal, use .encode('hex'):

>>> siphash24(b'\x00' * 16, b'hello, world!\n').encode('hex')
'f1473495a5aac262'

License

The reference C implementation of SipHash is bundled with this library. It was written by Jean-Philippe Aumasson and Daniel J. Bernstein, and is released under the CC0.

Six is bundled with this library. It was written by Benjamin Peterson, and is licensed under the MIT License.

All other software in this library is released under the UNLICENSE:

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org/