This series has also ended. If you have hands-on skills, you can combine the previous two series of articles (veracrypt, secure maintenance of account passwords, and the current virtualbox) to build an electronic safe by yourself.

Briefly describe the following steps:

1. Create a virtual computer, install win7 or win10 after disconnecting from the Internet, and then use Veracrypt to encrypt the system disk of the system in the virtual computer, and then share the files of the physical machine and the virtual machine.

2. Then perform various operations, such as installing or updating the wallet software. Because the network is disconnected and the environment is isolated, there is almost no risk of leaking keys or mnemonics (if the physical machine is also disconnected from the network and the physical machine is restarted after the wallet is created, there is almost no risk of leakage).

There is a possibility of leakage during backup, so please read the corresponding protection measures in the 3 series carefully. The offline wallet created in this way is even safer than the hardware wallet, because the hardware wallet may not only have software vulnerabilities, but also hardware risks, and may be cracked by others if lost.

However, this method has an obvious flaw: the environment construction is relatively complicated.

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There are two modes for copying a "virtual computer":

1. Full copy. Simply put, it means copying all files, which can be regarded as a new "virtual computer", but the virtual hard disk will also be copied, which means it will occupy twice the hard disk capacity.

2. Link replication. Share virtual disk files and snapshots at the time of replication. If you have the same basic information, this method can save disk usage. For example, if you want to have multiple Linux virtual computers, you only need one virtual computer, and then link and replicate it to multiple computers.

The operation method is also fool-proof, briefly described below:

1. Open the VirtualBox program.

2. Select the **virtual computer** that needs to be backed up, right-click, and then select "Copy". The rest is a fool-proof operation.

Note: If the virtual computer is copied by link, when exporting the virtual computer, the total file size is still the total size of the "full copy".

Export Virtual Machine

You can export a virtual computer to migrate it or back it up. The export is a full export, so the file will be larger and take longer to complete.

1. Open the VirtualBox program.

2. In the menu bar, select "Manage" -> "Export Virtual Computer", then select the virtual computer you want to export, and then click "Next".

3. The current recommendation for "Format" is to select "Open Virtualization Format 1.0". For the "File" storage location, select a location with enough reserved space. At the same time, it is recommended to change the "Save as type" to "ovf" (for example: win10_v20230327_1.ovf). For other configurations, use the default ones.

4. Wait for the export to complete.

> Note: If you select ovf format to export, there will be 3 or more files, mf file, ovf file, and 1 or more vmdk files. If you need to back up, you need to copy these 3 files. If the file is too large, you can use compression software to compress it into volumes.

Import virtual computer

1. Open the VirtualBox program.

2. In the menu bar, choose "Manage" -> "Import Virtual Computer", and then select the virtual computer you want to export.

3. Find and select the ova or ovf file, then click "Next", and then configure it according to the actual situation.

4. Wait for the export to complete.

Things to note when reinstalling or uninstalling VirtualBox

1. Write down the current version, for example: 7.0.10, and try to reinstall the same version (or a higher version) later.

2. The "Virtual Computer Directory" must be kept well. You can use this directory after reinstalling and use the previous "Virtual Computer".

Things to note when reinstalling the system

The precautions are similar to those for "Reinstall or uninstall VirtualBox", but it should be noted that the "virtual computer directory" must be preserved (migrated to another partition or hard disk, not in the same hard disk partition as the system disk), otherwise the previous "virtual computer" will be lost.

Disable unnecessary functions in the virtual machine system

1. Reduce virtual memory.

1. Computer -> Properties -> Advanced system settings -> Performance -> Advanced -> Virtual memory

2. Remove the option to automatically manage the paging file size for all drives

3. Because the virtual computer has only one disk by default (you can mount it later), click Custom Size and set the initial and maximum values ​​to 512

4. Click Settings

2. Turn off system restore. Just use VirtualBox's system snapshot.

1. Computer -> Properties -> Advanced system settings -> Performance -> System protection

2. Because the virtual computer has only one disk by default (you can mount it later), click Configure, and then select Turn off system protection