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lib/Auth/Yubikey_Decrypter.pm  view on Meta::CPAN

        # strip out the actual token
        my $publicID = substr($fulltoken,0,length($fulltoken)-32);
        my $token = substr($fulltoken,length($fulltoken)-32);

        # decode the token from modhex down to binary
        my $token_bin = &yubikey_modhex_decode($token);

        # Decrypt the token using it's key

        my $cipher = Crypt::Rijndael->new( $aeskey_bin );
        my $token_decoded_bin = $cipher->decrypt($token_bin);

        my $token_decoded_hex = unpack "H*", $token_decoded_bin;

        # get all the values from the decoded token
        my $secretid_hex        = substr($token_decoded_hex,0,12);
        my $counter_dec         = ord(substr($token_decoded_bin,7,1))*256+ord(substr($token_decoded_bin,6,1));
        my $timestamp_dec       = ord(substr($token_decoded_bin,10,1))*65536+ord(substr($token_decoded_bin,9,1))*256+ord(substr($token_decoded_bin,8,1));
        my $session_use_dec     = ord(substr($token_decoded_bin,11,1));
        my $random_dec          = ord(substr($token_decoded_bin,13,1))*256+ord(substr($token_decoded_bin,12,1));
        my $crc_dec             = ord(substr($token_decoded_bin,15,1))*256+ord(substr($token_decoded_bin,14,1));
        my $crc_ok              = &yubikey_crc_check($token_decoded_bin);

        return ($publicID,$secretid_hex,$counter_dec,$timestamp_dec,$session_use_dec,$random_dec,$crc_dec,$crc_ok);
}

=head2 yubikey_modhex_decode

Input : the modhex code
Output : decoded modhex code in hex

=cut

sub yubikey_modhex_decode
{
        my $mstring = $_[0];
        my $cset="cbdefghijklnrtuv";
        my $decoded="";
        my $hbyte=0;
        my $pos;
        for (my $i=0; $i<length($mstring);$i++)
        {
                $pos=index($cset,substr($mstring,$i,1));
                if ($i/2 != int($i/2))
                {
                        $decoded .= chr($hbyte+$pos);
                        $hbyte=0;
                }
                else
                {
                        $hbyte=$pos*16;
                }
        }
        return $decoded;
}

=head2 yubikey_crc_check

Performs a crc check on the decoded data

=cut

sub yubikey_crc_check
{
        my $buffer = $_[0];
        my $m_crc=0xffff;
        my $j;
        for(my $bpos=0; $bpos<16; $bpos++)
        {