Installation

$ pip install xxhash-cffi

$ apt-get install libcffi-dev python-dev gcc

$ yum install libcffi-devel python-devel gcc redhat-rpm-config

Usage

Module version and its backend xxHash library version can be retrieved using the module properties VERSION AND XXHASH_VERSION respectively.

>>> import xxhash_cffi as xxhash
>>> xxhash.VERSION
'1.0.1'
>>> xxhash.XXHASH_VERSION
'0.6.2'

This module is hashlib-compliant, which means you can use it in the same way as hashlib.md5.

update() – update the current digest with an additional string

digest() – return the current digest value

hexdigest() – return the current digest as a string of hexadecimal digits

intdigest() – return the current digest as an integer

copy() – return a copy of the current xxhash object

reset() – reset state

md5 digest returns bytes, but the original xxh32 and xxh64 C APIs return integers. While this module is made hashlib-compliant, intdigest() is also provided to get the integer digest.

Constructors for hash algorithms provided by this module are xxh32() and xxh64().

For example, to obtain the digest of the byte string b'Nobody inspects the spammish repetition':

>>> import xxhash_cffi as xxhash
>>> x = xxhash.xxh32()
>>> x.update(b'Nobody inspects')
>>> x.update(b' the spammish repetition')
>>> x.digest()
b'\xe2);/'
>>> x.digest_size
4
>>> x.block_size
16

More condensed:

>>> xxhash.xxh32(b'Nobody inspects the spammish repetition').hexdigest()
'e2293b2f'
>>> xxhash.xxh32(b'Nobody inspects the spammish repetition').digest() == x.digest()
True

An optional seed (default is 0) can be used to alter the result predictably:

>>> import xxhash_cffi as xxhash
>>> xxhash.xxh64('xxhash').hexdigest()
'32dd38952c4bc720'
>>> xxhash.xxh64('xxhash', seed=20141025).hexdigest()
'b559b98d844e0635'
>>> x = xxhash.xxh64(seed=20141025)
>>> x.update('xxhash')
>>> x.hexdigest()
'b559b98d844e0635'
>>> x.intdigest()
13067679811253438005

Be careful that xxh32 takes an unsigned 32-bit integer as seed, while xxh64 takes an unsigned 64-bit integer. Although unsigned integer overflow is defined behavior, it’s better to not to let it happen:

>>> xxhash.xxh32('I want an unsigned 32-bit seed!', seed=0).hexdigest()
'f7a35af8'
>>> xxhash.xxh32('I want an unsigned 32-bit seed!', seed=2**32).hexdigest()
'f7a35af8'
>>> xxhash.xxh32('I want an unsigned 32-bit seed!', seed=1).hexdigest()
'd8d4b4ba'
>>> xxhash.xxh32('I want an unsigned 32-bit seed!', seed=2**32+1).hexdigest()
'd8d4b4ba'
>>>
>>> xxhash.xxh64('I want an unsigned 64-bit seed!', seed=0).hexdigest()
'd4cb0a70a2b8c7c1'
>>> xxhash.xxh64('I want an unsigned 64-bit seed!', seed=2**64).hexdigest()
'd4cb0a70a2b8c7c1'
>>> xxhash.xxh64('I want an unsigned 64-bit seed!', seed=1).hexdigest()
'ce5087f12470d961'
>>> xxhash.xxh64('I want an unsigned 64-bit seed!', seed=2**64+1).hexdigest()
'ce5087f12470d961'

digest() returns bytes of the big-endian representation of the integer digest:

>>> import xxhash_cffi as xxhash
>>> h = xxhash.xxh64()
>>> h.digest()
b'\xefF\xdb7Q\xd8\xe9\x99'
>>> h.intdigest().to_bytes(8, 'big')
b'\xefF\xdb7Q\xd8\xe9\x99'
>>> h.hexdigest()
'ef46db3751d8e999'
>>> format(h.intdigest(), '016x')
'ef46db3751d8e999'
>>> h.intdigest()
17241709254077376921
>>> int(h.hexdigest(), 16)
17241709254077376921

Besides xxh32/xxh64 mentioned above, oneshot functions are also provided. By using oneshot functions we can avoid allocating XXH32/64_state on heap:

xxh32_digest(bytes, seed=0)

xxh32_intdigest(bytes, seed=0)

xxh32_hexdigest(bytes, seed=0)

xxh64_digest(bytes, seed=0)

xxh64_intdigest(bytes, seed=0)

xxh64_hexdigest(bytes, seed=0)

>>> import xxhash_cffi as xxhash
>>> xxhash.xxh64('a').digest() == xxhash.xxh64_digest('a')
True
>>> xxhash.xxh64('a').intdigest() == xxhash.xxh64_intdigest('a')
True
>>> xxhash.xxh64('a').hexdigest() == xxhash.xxh64_hexdigest('a')
True
>>> xxhash.xxh64_hexdigest('xxhash', seed=20141025)
'b559b98d844e0635'
>>> xxhash.xxh64_intdigest('xxhash', seed=20141025)
13067679811253438005L
>>> xxhash.xxh64_digest('xxhash', seed=20141025)
'\xb5Y\xb9\x8d\x84N\x065'

Caveats

Copyright and License

Copyright (c) 2014-2018 Yue Du - https://github.com/ifduyue

Licensed under BSD 2-Clause License