ii.com: Checking SHA-256 Checksums with certutil, sha256sum, 7-⁠Zip, and Dolphin

News

2023-November-4 As of today, this evolving⁠^[1] article has been on the web for 2 years.🕯🕯

Prerequisites

This article assumes you know how to…

launch a terminal emulator,
identify the command-line shell you are using (Bash, CMD, PowerShell, etc.), and
use a command line interface.

Terminology

SHA means Secure Hash Alogorithm. For details about this, see wikipedia.org/wiki/SHA-1 and wikipedia.org/wiki/SHA-2.

Why I wrote this

I’m in the midst of trying some Linux distributions and for each .iso file I download, I need to check its checksum as part of making sure I don’t install a trojan horse operating system.

Command-line tools

In this section I describe how to use the command-line tools certutil and sha256sum to display the SHA-⁠256 checksum of a file named FILENAME.

Step 1: Launch a terminal emulator

Launch a terminal emulator and cd (change directory) to the directory that contains FILENAME.

💡

On Windows, the following is an easy way to do this.

In File Explorer locate FILENAME's directory.
Shift+Right Click on a blank region in that directory.
In the pop-up context menu, choose one of the following options.
- Git Bash Here⁠^[2]⁠^[3]
- Open PowerShell window here
- Open in Windows Terminal
What you see in this context menu depends on what’s installed on your system.

Step 2 (Powershell and CMD): `certutil` command

In PowerShell or cmd.exe,^[4] run the following commands.

To check if the certutil command is available, run where.exe certutil
To check if FILENAME is in the current directory, run dir or dir |more

To display the SHA-256 checksum of FILENAME, run

certutil -hashfile FILENAME SHA256
                   ^^^^^^^^
                   use actual file name here

💡	To avoid typing more than the first few characters of FILENAME, you can use tab completion. To display alternate checksums, replace `SHA256` with `MD2`, `MD4`, `MD5`, `SHA1`, `SHA384`, or `SHA512`. To get help, run: `certutil -hashfile -?`

Step 2 (Unix-⁠like shells): `sha256sum` command

In a Unix-like shell, including Git Bash,^[3] run the following commands.

To check if the sha256sum command is available, run which sha256sum
To check if FILENAME is in the current directory, run ls or ls |less
To display the SHA-256 checksum of FILENAME, run sha256sum FILENAME

💡	To avoid typing more than the first few characters of FILENAME, you can use tab completion. To display the SHA-1 checksum, replace `sha256sum` with `sha1sum` above.

GUI tools

7-Zip’s right-click context menu

If the GUI variation of 7-Zip is installed on your system and if this option is set:

Integrate 7-Zip to shell context menu

Then, CRC-SHA > SHA-256 will be available when you Shift+Right Click on FILENAME in your GUI file manager.

💡	To view and possibly edit 7-Zip’s options, launch `7zFM` (7-⁠Zip File Manager) and choose Options… from its Tools menu.

Dolphin file manager’s right-click context menu

In Dolphin, which is KDE’s default GUI file manager, do the following.

Right-click FILENAME.
Choose Properties.
Select the Checksums tab.
Next to the checksum you’re interested in (e.g., SHA256), Select Calculate.

Checking SHA-256 Checksums with certutil, sha256sum, 7-⁠Zip, and Dolphin
Updated by nm 2022-July-4 💥