Digest::MD5 Bug?

Tuna has asked for the wisdom of the Perl Monks concerning the following question:

Can anyone explain this behavior?

#!/usr/bin/perl -w

use strict;
use Digest::MD5;


my %local;
my $file = shift || "/etc/passwd";

open(FILE, $file) or die "Can't open '$file': $!";
binmode(FILE);

my  $md5 = Digest::MD5->new;
while (<FILE>) 
{
  $md5->add($_);
}
close FILE;

$local{$file} = $md5->b64digest;

foreach my $k(keys %local) 
  {
    print "Key = $k\nValue = $local{$k}\n\n";
  }

print $md5->b64digest,  " $file\n";
[download]

The above prints:

Key = /etc/passwd
Value = Z+9+EFlyq2r1T90U9TiCiA
 
1B2M2Y8AsgTpgAmY7PhCfg /etc/passwd
[download]

Why would the fingerprint values be different?

Comment on Digest::MD5 Bug? Select or Download Code

Replies are listed 'Best First'.
(ichimunki) Re: Digest::MD5 Bug? by ichimunki (Priest) on Aug 15, 2001 at 21:16 UTC
from the perldoc: $md5->digest Return the binary digest for the message. Note that the digest operation is effectively a destructive, read-once operation. Once it has been performed, the Digest::MD5 object is automatically reset and can be used to calculate another digest value. $md5->b64digest Same as $md5->digest, but will return the digest as a base64 encoded string. You will have to run the whole file in again if you want to compute the fingerprint a second time.	[reply]
Re: Digest::MD5 Bug? by Hofmator (Curate) on Aug 15, 2001 at 21:21 UTC
RTFM ;-) it's clearly written in the perldoc `Note that the "digest" operation is effectively a destructive, read-once operation. Once it has been performed, the "Digest::MD5" object is automatically "reset" and can be used to calculate another digest value.` so no surprise there as you are calling the method twice. Update:Sorry for the duplicaton there, I was too slow ;-) -- Hofmator	[reply]


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