Since June the torrent download page⁽¹⁾⁽²⁾ includes a PGP key ID. However, the key is useless because a .sig file is not present. To obtain it the user has to go to the download section⁽³⁾, which makes that information pretty useless.

Three options are available:
1. Add a link to the .sig file in the torrent/release page itself.
2. Remove the PGP key ID, which is confusing without the .sig file.
3. Include the .sig file in the torrent itself.

The 3rd option would be ideal, but it comes with serious caveats. A torrent allows either one file or one directory with files. To have the .sig file, both ISO and the .sig file would have to be packed into a directory. That would require rearranging directory structure on the webseed mirrors. Such a change would also break many automated scripts users may be using, not to mention the general dislike for the change in layout.

Therefore, perhaps, option #1 is the best.

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⁽¹⁾ https://www.archlinux.org/releng/releases/2020.06.01/
⁽²⁾ https://www.archlinux.org/releng/releases/2020.07.01/
⁽³⁾ https://www.archlinux.org/download/