FireGPG

If you'ld like to encrypt or sign wiki content (with GnuPG aka GPG) have a look at the FireGPG Firefox extension.

It is completely client-side, thus you don't need support on the wiki / server side (and you don't need to trust the wiki / the server).

Todo: check http://enigform.mozdev.org/

Usage

Note: the key used to sign/encrypt the examples below is not public, thus you can't really verify the signature (and of course also not decrypt it, because you don't have that private key).

Signing

Just type in your content into a plain parser, select all your content, invoke tools > firegpg > clearsign.

FireGPG then will add the signature. Due to the plain parser, firegpg will see the text "as is" when the page is rendered, detects that it is GPG stuff and will render it nicely (client-side).

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

some example content
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Use GnuPG with Firefox : http://getfiregpg.org (Version: 0.7.7)
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=53FW
-----END PGP SIGNATURE-----

Encryption

Same as above, just use "sign and encrypt":

-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Use GnuPG with Firefox : http://getfiregpg.org (Version: 0.7.7)
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=M1/B
-----END PGP MESSAGE-----