/ 
Digest-SipHash-0.21
River stage one • 1 direct dependent • 1 total dependent
/ Digest::SipHash

NAME

Digest::SipHash - Perl XS interface to the SipHash algorithm

VERSION

$Id: SipHash.pm,v 0.21 2020/12/11 18:05:44 dankogai Exp $

SYNOPSIS

use Digest::SipHash qw/siphash/;
my $seed = pack 'C16', 0 .. 0xF;    # 16 chars long
my $str = "hello world!";
my ( $lo, $hi ) = siphash( $str, $seed );
#  $lo = 0x10cf32e0, $hi == 0x7da9cd17
my $u32 = siphash( $str, $seed )
#  $u32 = 0x10cf32e0

use Config;
if ( $Config{use64bitint} ) {
  use Digest::SipHash qw/siphash64/;
  my $uint64 = siphash64( $str, $seed );    # scalar context;
  # $uint64 == 0x7da9cd1710cf32e0
}

DESCRIPTION

SipHash is the default perl hash function for 64 bit builds now.

http://perl5.git.perl.org/perl.git/commit/3db6cbfca39da94d152d3e860e2aa79b9c6bb161

https://131002.net/siphash/

This module does only one thing - culculates the SipHash value of the given string.

EXPORT

siphash(), siphash32() and siphash64() on demand.

:all to all of above

SUBROUTINES/METHODS

siphash

my ($hi, $lo) = siphash($str [, $seed][, $no_downgrade]);
my $uint32    = siphash($str [, $seed][, $no_downgrade]);

Calculates the SipHash value of $src with $<$seed>.

If $seed is omitted, it defaults to $Digest:::SipHash::DEFAULT_SEED, which is set randomly upon initialization of this module.

If $seed is set but less than 16 bytes long, it is padded with $DEFAULT_SEED.

To be compatible with 32-bit perl, It returns a pair of 32-bit integers instead of a 64-bit integer. Since Hash::Util::hash_value() always returns the lower 32-bit first so that:

use Hash::Util qw/hash_seed hash_value/;
use Digest::SipHash qw/siphash/;
hash_value($str) == siphash($str, hash_seed()); # scalar context

always holds true when PERL_HASH_FUN_SIPHASH is in effect.

About Unicode

By default this module follows the same rules as Perl does regarding hashing, utf8 strings are passed to utf8::downgrade() with the $fail_ok flag set to true. This means that if the complete string can be downgraded to non-utf8 prior to hashing it will be, otherwise it will be left in utf8 form. This means that all strings which are string equivalent hash equivalently, and may not be what you want. In which case you can pass a third argument to the hash functions, which when true disables the downgrade behavior.

siphash32

just an alias of siphash.

siphash64

my $uint64 = siphash64($str [, $seed]);

Calculates the SipHash value of $src with $seed in 64-bit. Available on 64-bit platforms only.

AUTHOR

Dan Kogai, <dankogai+cpan at gmail.com>

BUGS

Please report any bugs or feature requests to bug-digest-siphash at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Digest-SipHash. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Digest::SipHash

You can also look for information at:

SEE ALSO

Hash::Util, https://131002.net/siphash/

ACKNOWLEDGEMENTS

SipHash: a fast short-input PRF

by Jean-Philippe Aumasson & Daniel J. Bernstein

https://131002.net/siphash/

LICENSE AND COPYRIGHT

csiphash.c

Copyright (c) 2013 Marek Majkowski

MIT License http://opensource.org/licenses/MIT

https://github.com/majek/csiphash

The rest of this module

Copyright 2013 Dan Kogai.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

http://www.perlfoundation.org/artistic_license_2_0

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

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