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=head1 NAME |
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|
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Digest::Hashcash - generate Hashcashes (http://www.hashcash.org) |
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|
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=head1 SYNOPSIS |
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|
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use Digest::Hashcash; |
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|
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=head1 DESCRIPTION |
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|
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This module implements the hashcash hash (or digest, although it's |
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not clearly a digest). For all your information needs please visit |
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http://www.hashcash.org. |
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|
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One thing to note about this module is that it requires ISO C99 support, |
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both in your compiler and your standard library. If you don't have a |
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compiler that supports ISO C, get gcc at http://gcc.gnu.org/ :) |
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|
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=over 4 |
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|
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=cut |
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|
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package Digest::Hashcash; |
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|
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use Time::Local; |
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|
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require XSLoader; |
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|
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no warnings; |
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|
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$VERSION = 0.01; |
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|
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XSLoader::load Digest::Hashcash, $VERSION; |
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|
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=item $cipher = new [param => value...] |
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|
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=over 4 |
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|
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=item size => 20 + some |
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|
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The number of collisions, in bits. Every bit increases the time to create |
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the token (and thus the cash) by two. |
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|
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=item uid => "" |
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|
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A string used to make the token more unique (e.g. the senders address) |
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and reduce token collisions. The string must only contain characters |
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valid for the trial part of the token, e.g. uuencoded, base64 or |
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e-mail-address-parts are useful here. |
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|
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=item extrarand => 0 |
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|
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The extra bytes of randomness to add to the token in addition to the |
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standard amount. Each byte adds a little bit over 6 bit of randomness to |
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the token. |
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|
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The standard amount of randomness is 8 (> 51 bits of randomness). |
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|
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=item timestamp => 0 |
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|
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The timestamp to use. A value of 0 (the default) means to use the current |
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time. |
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|
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=back |
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|
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=item $token = $cipher->hash($data [, param => value...]) |
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|
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Creates and returns a new token. This can take some time. |
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|
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Any additional parameters are interpreted the same way as arguments to |
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C<new>. |
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|
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=item $prefix = $cipher->verify($token [, param => value...])) |
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|
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Checks the given token and returns true if the token has the minimum |
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number of prefix bits, or false otherwise. The value returned is actually |
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the number of collisions, so to find the number of collisions bits specify |
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C<< collisions => 0 >>. |
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|
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Any additional parameters are interpreted the same way as arguments to |
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C<new>. |
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|
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=item $resource = $cipher->resource($token) |
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|
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Returns the resource part, or C<undef>. |
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|
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=item $tstamp = $ciper->timestamp($token) |
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|
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Returns the timestamp part (in the same format as perl's C<time>), or |
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C<undef>. |
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|
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=back |
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|
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=cut |
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|
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sub new { |
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my $class = shift; |
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|
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bless { @_ }, $class; |
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} |
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|
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sub hash { |
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my $self = shift; |
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my %arg = (%$self, resource => @_); |
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|
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&_gentoken(@arg{qw(size timestamp resource uid extrarand)}); |
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} |
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|
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sub verify { |
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my ($self, $token) = (shift, shift); |
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my %arg = (%$self, @_); |
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|
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my $prefix = &_prefixlen($token); |
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|
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$prefix < $arg{size} |
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? undef |
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: $prefix; |
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} |
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|
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sub resource { |
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my ($self, $token) = @_; |
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|
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$token =~ /^\d+:\d*:(.*):/ |
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or return undef; |
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|
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return $1; |
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} |
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|
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sub timestamp { |
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my ($self, $token) = @_; |
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|
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$token =~ /^\d+:(\d*):.*:/ |
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or return undef; |
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|
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my ($y, $m, $d, $H, $M, $S); |
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local $_ = $1; |
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$y = /\G(\d\d)/gc ? $1 : return undef; |
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$m = /\G(\d\d)/gc ? $1 : 1; |
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$d = /\G(\d\d)/gc ? $1 : 1; |
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$H = /\G(\d\d)/gc ? $1 : 0; |
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$M = /\G(\d\d)/gc ? $1 : 0; |
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$S = /\G(\d\d)/gc ? $1 : 0; |
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|
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return timegm $S, $M, $H, $d, $m - 1, $y; |
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} |
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|
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=head1 SEE ALSO |
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|
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L<http://www.hashcash.org>. |
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|
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=head1 BUGS |
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|
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* There is a y2k+100 problem, as I always assume the same as Time::Local. |
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This is a problem with the hashcash specification, which specifies |
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yeras as 2 digits :( |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <pcg@goof.com> |
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http://home.schmorp.de |
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|
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=cut |
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|
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1; |
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|
