Because the partitions are encrypted, it's not possible to resize them using the normal tools such as parted/gparted. This is because the actual partition on disk is not a valid file system, but just an encrypted block, which appears like a string of seemingly random data.
You can delete them and totally recreate them. If you only need to resize your swap, and to do this you don't need to resize any other (encrypted) partition, then trashing and re-installing it is going to be easy. But I assume that's not the case, as not many people will just leave unallocated space on the drive should they want to increase the swap partition (unless you're able to expand it into your un-encrypted root partition?). Otherwise you may be able to recreate your swap and home partitions, and copy across your files from an external drive. You will probably need to be familiar with cryptsetup and the way luks works. Otherwise a clean install is in order.
A common configuration with LUKS is to use LVM on top of it, which gives you a much easier way of resizing partitions inside your encrypted block - because LUKS means you have multiple partitions inside the same block, you don't need to resize the container to resize the partitions inside. If you are going to resort to a clean install, the alternate installer CD makes setting up a LUKS partition with LVM on top of it easy.
Most online tutorials you'll find about resizing a LUKS partition are actually about resizing LVM volumnes inside of one instead.
