Can't Verify
 

I downloaded Linuxmint 21 Cinnamon 3 times from different sources but still get wrong result when I run /Downloads$ sha256sum -b sha256sum.txt. I am currently running Linuxmint 20.3 Cinnamon. I downloaded the .iso, the sha26sum.txt and sha26sum.txt.gpg to Downloads. I then ran /Downloads$ sha256sum -b sha256sum.txt and get
ad03e2eadb67273ac271b17bce35c902e55ddd27bbb39ddc32da97160b70caf2 *sha256sum.txt
which does not match f524114e4a10fb04ec428af5e8faf7998b18271ea72fbb4b63efe0338957c0f3 *linuxmint-21-cinnamon-64bit.iso.

Did you follow the verify ISO image web page?
https://linuxmint-installation-guide...st/verify.html

I downloaded the cinnamon ISO file from the John Madison University website.
sha256sum utility verifies the sha256 checksum value of the ISO file. The sha256sum.txt.gpg verifies the integrity of the sha256sum.txt file.

Yes

It isn't obvious from your original post.

So what's missing from that post? I did:
~/Downloads$ gpg --verify sha256sum.txt.gpg sha256sum.txt
gpg: Signature made Fri 29 Jul 2022 06:26:29 AM CDT
gpg: using RSA key 27DEB15644C6B3CF3BD7D291300F846BA25BAE09
gpg: Good signature from "Linux Mint ISO Signing Key <root@linuxmint.com>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 27DE B156 44C6 B3CF 3BD7 D291 300F 846B A25B AE09

The only check in post #1 was:
but it should be
There is also the note on the page

/Downloads$ sha256sum -b linuxmint-21-cinnamon-64bit.iso
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 *linuxmint-21-cinnamon-64bit.iso
Still not matching sha26sum.txt
f524114e4a10fb04ec428af5e8faf7998b18271ea72fbb4b63efe0338957c0f3 *linuxmint-21-cinnamon-64bit.iso

Sorry about that, I saw download failed when I looked in the Library.

Downloaded iso and matches sha26sum.txt
In the beginning I was trying to verify the sha26sum.txt by doing /Downloads$ sha256sum -b sha256sum.txt. I now realize that ~/Downloads$ gpg --verify sha256sum.txt.gpg sha256sum.txt does that. I did have to attempt downloading from 6 different mirrors until one worked. Have not done this since I downloaded 20.0