Initial Commit

database/perl/vendor/lib/Crypt/OpenPGP/MDC.pm

@@ -0,0 +1,97 @@
+package Crypt::OpenPGP::MDC;
+use strict;
+
+use Crypt::OpenPGP::Digest;
+use Crypt::OpenPGP::ErrorHandler;
+use base qw( Crypt::OpenPGP::ErrorHandler );
+
+sub new {
+    my $mdc = bless { }, shift;
+    $mdc->init(@_);
+}
+
+sub init {
+    my $mdc = shift;
+    my %param = @_;
+    if (my $data = $param{Data}) {
+        my $dgst = Crypt::OpenPGP::Digest->new('SHA1');
+        $mdc->{body} = $dgst->hash($data);
+    }
+    $mdc;
+}
+
+sub digest { $_[0]->{body} }
+
+sub parse {
+    my $class = shift;
+    my($buf) = @_;
+    my $mdc = $class->new;
+    $mdc->{body} = $buf->get_bytes($buf->length - $buf->offset);
+    $mdc;
+}
+
+sub save { $_[0]->{body} }
+
+1;
+__END__
+
+=head1 NAME
+
+Crypt::OpenPGP::MDC - MDC (modification detection code) packet
+
+=head1 SYNOPSIS
+
+    use Crypt::OpenPGP::MDC;
+
+    my $mdc = Crypt::OpenPGP::MDC->new( Data => 'foobar' );
+    my $digest = $mdc->digest;
+    my $serialized = $mdc->save;
+
+=head1 DESCRIPTION
+
+I<Crypt::OpenPGP::MDC> is a PGP MDC (modification detection code) packet.
+Such a packet is used alongside Encrypted-MDC data packets so that
+modifications to the ciphertext can be detected. The MDC packet contains
+a C<SHA-1> digest of the plaintext for comparison with the decrypted
+plaintext.
+
+You generally will never need to construct a I<Crypt::OpenPGP::MDC>
+packet yourself; usage is by the I<Crypt::OpenPGP::Ciphertext> object.
+
+=head1 USAGE
+
+=head2 Crypt::OpenPGP::MDC->new( [ Data => $data ] )
+
+Creates a new MDC packet object and returns that object. If you do not
+supply any data I<$data>, the object is created empty; this is used, for
+example, in I<parse> (below), to create an empty packet which is then
+filled from the data in the buffer.
+
+If you wish to initialize a non-empty object, supply I<new> with
+the I<Data> parameter along with a value I<$data>. I<$data> should
+contain the plaintext prefix (length = cipher blocksize + 2), the actual
+plaintext, and two octets corresponding to the hex digits C<0xd3> and
+C<0x14>.
+
+=head2 $mdc->save
+
+Returns the text of the MDC packet; this is the digest of the data passed
+to I<new> (above) as I<$data>, for example.
+
+=head2 Crypt::OpenPGP::MDC->parse($buffer)
+
+Given I<$buffer>, a I<Crypt::OpenPGP::Buffer> object holding (or
+with offset pointing to) an MDC packet, returns a new <Crypt::OpenPGP::MDC>
+object, initialized with the MDC data in the buffer.
+
+=head2 $mdc->digest
+
+Returns the MDC digest data (eg. the string passed as I<$data> to
+I<new>, above).
+
+=head1 AUTHOR & COPYRIGHTS
+
+Please see the Crypt::OpenPGP manpage for author, copyright, and
+license information.
+
+=cut