Open the Disk Utility Tool by searching for it in Spotlight or by going to Finder->Applications->Utilities->Disk Utility. Disk Utility Tool will allow you to create partitions on your hard drive and then encrypt the partition you want to encrypt.ġ. The main use of Disk Utility Tool is when you don’t want to encrypt the whole drive but only a part of it. Hence, it is suitable only for a new hard drive. One thing to keep in mind is that this method will erase all your data before it encrypts the hard drive. You can also encrypt your external hard drive using the Disk Utility Tool.