How to verify downloaded file with .sig file?

command, command-line, shell, signature, verify

Solution

You need to import public key: `C3C45C06`

Can be done in three steps.

find public key ID:

$ gpg gcc-4.7.2.tar.gz.sig 
gpg: Signature made Čt 20. září 2012, 12:30:44 CEST using DSA key ID C3C45C06
gpg: Can't check signature: No public key

import the public key from key server. It's usually not needed to choose key server, but it can be done with `--keyserver <server>`. Keyserver examples.

$ gpg --recv-key C3C45C06
gpg: requesting key C3C45C06 from hkp server keys.gnupg.net
gpg: key C3C45C06: public key "Jakub Jelinek <jakub@redhat.com>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1

If the command error's out with a timeout, you may be behind a firewall that is blocking the default gpg port. Try using the `--keyserver' option with port 80 (almost all firewalls allow port 80 b/c of web browsing):

$ gpg --keyserver hkp://${HOSTNAME}:80 --recv-keys ${KEY_ID}

verify signature:

$ gpg gcc-4.7.2.tar.gz.sig 
gpg: Signature made Čt 20. září 2012, 12:30:44 CEST using DSA key ID C3C45C06
gpg: Good signature from "Jakub Jelinek <jakub@redhat.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: 33C2 35A3 4C46 AA3F FB29  3709 A328 C3A2 C3C4 5C06

The output should say "Good signature".

gpg: WARNING: This key is not certified with a trusted signature!

Is for another question ;)

Problem

When I download GCC, it also has a `.sig` file, and I think it is provided to verify downloaded file. (I downloaded GCC from here). But I can't figure out how should I use it. I tried `gpg`, but it complains about public key. ``` [root@localhost src]# gpg --verify gcc-4.7.2.tar.gz.sig gcc-4.7.2.tar.gz gpg: Signature made Thu 20 Sep 2012 07:30:44 PM KST using DSA key ID C3C45C06 gpg: Can't check signature: No public key [root@localhost src]# ``` How can I verify downloaded file with `.sig` file?

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