Crypt::Keyczar::Verifier - Verify data usign sets of symmetric or asymmetric keys.


Crypt-Keyczar documentation Contained in the Crypt-Keyczar distribution.

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NAME

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Crypt::Keyczar::Verifier - Verify data usign sets of symmetric or asymmetric keys.

SYNOPSIS

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  use Crypt::Keyczar::Verifier;

  my $verifier = Crypt::Keyczar::Verifier->new('/path/to/keyset');
  $verifier->verify($message, $signature) ? 'OK' : 'NG';

DESCRIPTION

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Crypt::Keyczar::Verifier are used strictly to verify signatures. Typically, Verifiers will read sets of public keys, although may also be instantiated with sets of symmetric or private keys.

METHOD

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* new($keyset_path)

Create a new Crypt::Keyczar::Verifier object with a file-based key set location. This will attempt to read the keys using a Crypt::Keyczar::FileReader. The corresponding key set must have a purpose of either 'VERIFY' or 'SIGN_AND_VERIFY'.

* new($reader_object)

Create a new Crypt::Keyczar::Verifier object with a Crypt::Keyczar::Reader object.

* verify($message, $signature)

Verifies a $sigunature on the given $message.

SEE ALSO

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keyczar in bin, Crypt::Keyczar, Crypt::Keyczar::Signer, http://www.keyczar.org/

AUTHOR

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Hiroyuki OYAMA <oyama@mixi.co.jp>

LICENSE

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Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.


Crypt-Keyczar documentation Contained in the Crypt-Keyczar distribution.

package Crypt::Keyczar::Verifier;
use base 'Crypt::Keyczar';
use strict;
use warnings;
use Carp;


sub verify {
    my $self = shift;
    my ($data, $signature, $hidden) = @_;

    if (!defined $signature || length $signature < Crypt::Keyczar::HEADER_SIZE()) {
        croak "signature is short";
    }

    my $hash_size = Crypt::Keyczar::KEY_HASH_SIZE();
    my ($v, $hash, $mac) = unpack "C1 a$hash_size a*", $signature;
    if ($v != Crypt::Keyczar::FORMAT_VERSION()) {
        croak "bad format version: $v";
    }
    my $key = $self->get_key($hash);
    if (!$key) {
        croak "key not found"; 
    }

    my $engine = $key->get_engine();
    my $expiration_time;
    if ($key->can('digest_size') && length $mac > $key->digest_size) {
        ($expiration_time, $mac) = unpack "N1 a*", $mac;
        $engine->update(pack 'N1', $expiration_time);
    }
    if (defined $hidden && length $hidden > 0) {
        $engine->update($hidden);
    }
    $engine->update($data);
    $engine->update(Crypt::Keyczar::FORMAT_BYTES());
    my $result = $engine->verify($mac);
    return $result if !$result;
    if (defined $expiration_time) {
        return time() < $expiration_time;
    }
    return $result;
}

1;
__END__