Idea: GPG signatures within HTML
Sometimes a problem appears with publishing information on the Web, when the authenticity of document, especially a widely-distributed one, has to be checked. I am not aware about any mechanism available presently. A trick with HTML (or SGML in general) tag and a comment, a browser plugin (or manual operation over saved source), and a GPG signature over part of the HTML file should do the job, with maintaining full backward compatibility and no problems for the users not using this scheme. It should be possible to make this HTML construction: <HTML> <BODY> blah blah blah blah blah unsigned irrelevant part of the document, eg. headers and sidebars which change with the site design <SIGNED SCHEME="GPG"><!-- -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 --!> This is the PGP-signed part of the HTML document. <!-- -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.1.91 (MingW32) - GPGrelay v0.893 ihas7Ds9fXLR9ksWRdwNZXNA8SdshwAJ9zwXFDgvdg5G2mqXp5BD4Sx2ZmjwCfSs70 Kj8sQor6i+MUZBmp5pdM1vU= =hIsR -----END PGP SIGNATURE----- --!></SIGNED> the unsigned rest of the HTML document </BODY></HTML> The <SIGNED>...</SIGNED> tags are ignored by browsers that don't know them, and provide leads for eventual browser plugins. The <!-- --> comments are used to hide the signature from the user in standard browsers. The scheme is designed to allow signing only parts of documents, so they could be published in fast-changing environments like blogs or on dynamically generated pages, and to have many different signed parts on one page. It should also allow manual checking of the signature, eg. by curl http://url | gpg --verify Feel free to use the idea if it is good. Opinions, comments?
There is a problem with images and other inline objects. There is a solution, too. The objects included into the document can get their hash calculated and included in their tag; eg, <IMG SRC="image.jpg" HASH="SHA1:4e1243bd22c66e76c2ba9eddc1f91394e57f9f83"> The tag has to be in the signed part of the document, so the hash can't be tampered with. Full digital signatures should be possible as well, eg. <IMG SRC="image.jpg" SIGNATURE="http://where.is.the/signature.asc"> or <IMG SRC="image.jpg" SIGNATURE="identifier"> some HTML code here <SIGNATURE TYPE="gpg" NAME="identifier"><!-- -----BEGIN PGP SIGNATURE----- Version: GnuPG v0.9.11 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQA31UOQaLeriVdUjc0RAjhBAJ4u1k5ex8+ZAtYi737GFXPOiBc51gCfU5+8 is2rD6L/6fIOWttfh5CYUW0= =WOv2 -----END PGP SIGNATURE----- --></SIGNATURE> This way doesn't depend on the part of the document being signed, as the signature can't be effectively tampered with undetected anyway. Same scheme could be used in <A HREF> tags, allowing automated checking of signatures or hashes of downloaded binary files.
Moin, Am Sat, 22 Nov 2003 14:54:39 +0100 (CET) schrieb Thomas Shaddack:
A trick with HTML (or SGML in general) tag and a comment, a browser plugin(or manual operation over saved source), and a GPG signature over part of the HTML file should do the job, with maintaining full backward compatibility and no problems for the users not using this scheme.
Opinions, comments?
This is already done, although I'm not aware of any browser supporting an automated verification. For an example look at the HTML source of http://www.bundesverfassungsgericht.de/entscheidungen/frames/rk20030827_2bvr... -- Henryk Plvtz Gr|_e aus Berlin ~~~~~~~ Un-CDs, nein danke! http://www.heise.de/ct/cd-register/ ~~~~~~~ ~ Help Microsoft fight software piracy: Give Linux to a friend today! ~
participants (2)
-
Henryk Plötz -
Thomas Shaddack