Verify checksums and GPG signatures on Slackware

1. Goal

Validate downloaded files before installing ISOs, packages, or scripts from external sources.

2. Files and components involved

sha256sum
md5sum
gpg
CHECKSUMS.md5
CHECKSUMS.asc

3. Operational flow

sha256sum file.iso
gpg --recv-keys KEYID
gpg --verify CHECKSUMS.asc CHECKSUMS.md5

4. Operational verification

md5sum -c CHECKSUMS.md5
gpg --list-keys KEYID

5. Practical notes

Apply these changes during a maintenance window and keep a backup of the original files for a quick rollback.

Tightening a policy without an alternative access path is the fastest way to lock out legitimate users as well.

Quick checklist

[ ] Backup or copy of the existing configuration completed
[ ] Files and commands updated as expected
[ ] Local test completed successfully
[ ] Logs or final output verified
[ ] Rollback procedure documented

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