[Solved] Question about ISO verification

[user123456789]

I installed Linux Mint 18.2 a few days ago but I did not verify the ISO.
I downloaded the ISO again today and this is what appears in the terminal at the end of the verification process:

Code: Select all

markov@host /home/ISO $ gpg --keyserver keyserver.ubuntu.com --recv-key "27DE B156 44C6 B3CF 3BD7  D291 300F 846B A25B AE09"
gpg: requesting key A25BAE09 from hkp server keyserver.ubuntu.com
gpg: key A25BAE09: public key "Linux Mint ISO Signing Key <root@linuxmint.com>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
markov@host /home/ISO $ gpg --verify sha256sum.txt.gpg sha256sum.txt
gpg: Signature made Thu 29 Jun 2017 06:13:16 PM CEST using RSA key ID A25BAE09
gpg: Good signature from "Linux Mint ISO Signing Key <root@linuxmint.com>"
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
markov@host /home/ISO $ 

Guide: https://linuxmint.com/verify.php.

What does that mean?
On the other hand, how do I check whether my current system is safe?

I thought that if this ISO is authentic, and all of the other ISOs installed in the last few days are, maybe no one altered it.

[catweazel]

A 'trusted' key issued by a 'trusted authority' and that costs money. The message is simply telling you that root@linuxmint.com didn't pay for a trusted signature.

[user123456789]

Thank you for answering.

How about the other question?
Do I have to install Mint again or my current installation is likely safe?

[MintBean]

It's highly unlikely you downloaded a hacked ISO - someone else would surely have reported the breach. Of course, the only way to be 100% sure that it isn't compromised or corrupted is to test the ISO you install from, which presumably you've deleted.

[user123456789]

How do I create a bootable USB with Mint in it using Mint?
Last time I did this I was using Windows.

[Pierre]

with your new LinuxMint 18.2 - - goto Menu - Accessories - USB Image Writer
and use that to write your new ISO to your USB Stick.

[user123456789]

Just reinstalled Mint again, thanks everyone!