BitLocker Encryption: Entire Drive or Used Disk Space Only?

In fact, encrypting used disk space only appears in the context of full disk encryption taking too long. Next, I will explain how they differ in terms of security, encryption duration, applicable scenarios, and post-encryption usage. Let’s explore these differences.

Security

For used disk space only, BitLocker only encrypts the portion that contains data, leaving the unused space unencrypted. In this case, despite the used space being encrypted, there may still be some sectors containing unencrypted data that were deleted previously. These data can potentially be recovered until they are overwritten by new data.

When encrypting the entire drive, the full drive space will be encrypted, whether it is used or not. Therefore, even data that was deleted previously on this drive will be protected with BitLocker encryption.

You can find more information on this official page.

Encryption Duration

Encrypting used disk space only is faster than encrypting the entire drive, especially when only a small portion of the drive is used. This discrepancy in speed is expected due to the difference in encryption sizes.

Applicable Scenarios

As mentioned by the BitLocker Setup wizard, if you want to encrypt a new drive, selecting to encrypt used disk space only is a better choice. It takes less time, and there's no difference in security compared to full encryption.

If you want to enable BitLocker for a used drive, encrypting the entire drive is a more secure choice. Although this mode will take longer, it can protect your data stored on the drive more securely.

Post-encryption Usage

No matter which encryption method is used, the way to access data is the same.

Transparency: Aside from needing to enter the correct credentials to unlock the encrypted drive, the process of accessing data is no different from accessing a normal drive. In terms of user perception, it feels like nothing has changed.

Performance: The impact on performance is minimal. You can learn more details from "Does BitLocker encryption impact computer performance?".

Conclusion

In summary, as the BitLocker Setup wizard shows, if you encrypt a new drive, encrypting used disk space only is a better option. For encrypting a used drive, encrypting the entire drive will be more secure.

Consider your requirements and choose the encryption method that best suits your needs.

If your computer doesn't support BitLocker, you can use iSunshare BitLocker Genius for Windows to enable BitLocker functionality.