use warnings;
use strict;
use MIME::Base64;

my $base64text = encode_base64('This is some Base64 encoded text');
my $notbase64text = 'This is text is not Base64 encoded';

print is_base64($base64text) || "\nNot Base64\n";
print is_base64($notbase64text) || "\nNot Base64\n";

sub is_base64{
  #Returns the decoded data on success, undef on failure
  my $data = shift;
  return(undef) unless ($data =~ /^[A-Za-z0-9+\/=]+$/); #test for valid Base64 string
  if (length ($data)%4==0){
    print "Valid Base64\n";
    my $decoded = decode_base64($data);
    return( $decoded );
  } else {
    print "Invalid Base64\n";
    return(undef);
  }
}