Some time ago, I downloaded and authenticated the ISO file for Linux Mint Version 18 (see: Verifying the Linux Mint 18 ISO file), using a mostly manual method, through a series of Linux commands. A much easier method is to use the GtkHash app which provides a graphical user interface (GUI).
The latest release of Linux Mint, Version 19.3 (Tricia), was distributed a few days ago. I downloaded the 64-bit Cinnamon version as the file linuxmint-19.3-cinnamon-64bit.iso. In order to authenticate the downloaded file, I also obtained the hash information from https://linuxmint.com/verify.php, by clicking on the 19.3 button, and selecting sha256sum.txt. This file contains the 256-bit hash values for all of Tricia’s ISO files. In particular, the relevant value for the 64-bit Cinnamon file is listed as:
GtkHash can be installed through the Software Manager. Running this program produces a dialogue box in which one can browse for the downloaded ISO file, in the box labelled File, and enter the relevant hash code into the box labelled Check. Pressing the Hash button Hash causes the hash values for the downloaded file to be generated and compared to the hash value entered (from sha256sum.txt).
If the two hash values match the a check mark is displayed against each matching entry (e.g. see the Check and SHA256 boxes in the image below).
Linux Mint 19.3 “Tricia” Cinnamon released!
Verifying the Linux Mint 18 ISO file
How To Verify Checksum In Linux [Beginner Guide]