There are various ways to install OnionShare for Linux, but the recommended way is to use either the `Flatpak <https://flatpak.org/>`_ or the `Snap <https://snapcraft.io/>`_ package.
Flatpak and Snap ensure that you'll always use the newest version and run OnionShare inside of a sandbox.
You can verify that the package you download is legitimate and hasn't been tampered with by verifying its PGP signature.
For Windows and macOS, this step is optional and provides defense in depth: the OnionShare binaries include operating system-specific signatures, and you can just rely on those alone if you'd like.
Packages are signed by Micah Lee, the core developer, using his PGP public key with fingerprint ``927F419D7EC82C2F149C1BD1403C2657CD994F73``. You can download Micah's key `from the keys.openpgp.org keyserver <https://keys.openpgp.org/vks/v1/by-fingerprint/927F419D7EC82C2F149C1BD1403C2657CD994F73>`_.
You must have GnuPG installed to verify signatures. For macOS you probably want `GPGTools <https://gpgtools.org/>`_, and for Windows you probably want `Gpg4win <https://www.gpg4win.org/>`_.
You can find the signatures (as ``.asc`` files), as well as Windows, macOS, Flatpak, Snap, and source packages, at https://onionshare.org/dist/ in the folders named for each version of OnionShare.
Once you have imported Micah's public key into your GnuPG keychain, downloaded the binary and and ``.asc`` signature, you can verify the binary for macOS in a terminal like this::
If you don't see 'Good signature from', there might be a problem with the integrity of the file (malicious or otherwise), and you should not install the package. (The "WARNING:" shown above, is not a problem with the package, it only means you haven't already defined any level of 'trust' of Micah's PGP key.)
If you want to learn more about verifying PGP signatures, the guides for `Qubes OS <https://www.qubes-os.org/security/verifying-signatures/>`_ and the `Tor Project <https://support.torproject.org/tbb/how-to-verify-signature/>`_ may be useful.
