This is an example workflow to encrypt an USB thumbdrive with HSF+ (Journaled) with diskutil
using the command line.
Assuming you start with a MS-DOS formatted USB stick.
Step 1: List all currently mounted disks diskutil list
:
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *8.1 GB disk2
1: DOS_FAT_32 MYSTORAGE 8.1 GB disk2s1
You see the disk MYSTORAGE
has the identifier disk2s1
and is DOS_FAT_32
formatted.
Step 2: Now format the disk disk2
as HSF+ (Journaled):
diskutil eraseDisk JHFS+ "New Storage" GPT disk2
The name of the disk will be "New Storage". At this time it is not yet encrypted. Look at the list of disks diskutil list
:
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *8.1 GB disk2
1: EFI EFI 209.7 MB disk2s1
2: Apple_HFS New Storage 7.7 GB disk2s2
Step 3: Now you see the "New Storage" partition with identifier disk2s2
. Encrypt this partition using:
diskutil cs convert disk2s2 -passphrase
Enter the passphrase when prompted.
If you list the disks now, you also see the encrypted logical volume diskutil list
:
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *8.1 GB disk2
1: EFI EFI 209.7 MB disk2s1
2: Apple_CoreStorage New Storage 7.7 GB disk2s2
3: Apple_Boot Boot OS X 134.2 MB disk2s3
/dev/disk3 (external, virtual):
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS New Storage +7.3 GB disk3
Logical Volume on disk2s2
8B474F90-34B7-49FE-95E0-E8B260C51CCF
Unlocked Encrypted
If you skip step 3, you can also encrypt the disk using Finder:

Just right-click on the drive and select "Encrypt drive-name".
Caution: If you choose this alternative approach, the disk gets formatted as APFS encrypted disk!