So let’s say you start having trouble with your internal drive, and want to troubleshoot it. Or maybe you want to use your portable macOS installation on another compatible Mac. To boot from your external Sierra drive, plug it into the Mac in question, press the power button, and hold the “Option key until the recovery disk screen appears. One final point—if you encrypt a drive, don’t expect to be able to read its files on earlier versions of the operating system. A drive you encrypt under 10.9 won't be readable with a Mac.
Encrypting a portable USB flash drive is a great way to protect sensitive data so as no other persons except you can open and modify the files. This guide will demonstrate how to securely encrypt a USB flash drive within macOS so that the data stored on it cannot be read nor accessed without entering a secure password.
This article will introduce two solutions to encrypt USB flash drive on macOS Catalina/Mojave/High Sierra.
Solution 1: Encrypt USB flash drive with Bitlocker on macOS Catalina/Mojave/High Sierra
Truecrypt is not secure. With GDPR (General Data Protection Regulation) now in full force, we have to make our drives being encrypted.
Up to now, Bitlocker is the most truely secure encryption solution built-in Windows. Although Microsoft has not implemented Bitlocker client for macOS, but with the help of M3 Bitlocker Loader for Mac, encrypting USB flash drive with Bitlocker can be done on macOS Catalina/Mojave/High Sierra/Sierra and Mac OS X.
If you are a cross platform user, Bitlocker is the best choice to encrypt your USB flash drive and Bitlocker encrypted USB flash drive can be easily accessed on Windows without an extra software.
Tutorial to encrypt/password protect USB flash drive with Bitlocker on macOS
Step 1: Download and install M3 Bitlocker Loader for Mac on your Mac computer.
Step 2: Insert USB flash drive (The file system must be NTFS, FAT32 or exFAT) into your Mac computer.
Step 3: Launch M3 Bitlocker Loader for Mac.
Step 4: Click 'Encrypt' button in toolbar of M3 Bitlocker Loader for Mac.
Step 5: Select USB flash drive and then click Encrypt.
Step 6: Enter the password.
Step 7: Save the recovery key.
Step 8: After Bitlocker drive encryption completes, the USB flash drive will be password protected and then we can use M3 Bitlocker Loader for Mac to read/write Bitlocker encrypted USB flash drive on macOS Catalina 10.15/Mojave 10.14/High Sierra 10.13/Sierra 10.12 and Mac OS X 10.11/10.10/10.9/10.8 Operating Systems.
Solution 2: Encrypt USB flash drive with FileVault on macOS Catalina/Mojave/High Sierra
FileVault is a disk encryption tool built in Mac OS X El Capitan and later version, but USB flash drive encrypted with FileVault cannot be opened by Windows. The password you choose to encrypt your USB flash drive cannot be changed once the encryption completes.
Tutorial to encrypt USB flash drive with FileVault
Step 1: Insert your USB flash drive into your Mac computer.
Step 2: Open the Finder and right click USB flash drive in the left sidebar.
Step 3: Select Encrypt.
Step 4: Enter the password and confirm a password.
Windows 10 Encrypt External Drive
Step 5: Encryption will take a few minutes; once complete, you USB flash drive will be fully protected with a password.