OpenBSD's new John Hancock

mancha · 05-06-2014, 12:52 PM

With release 5.5, OpenBSD began digitally signing its code. To achieve this, OpenBSD developer Ted Unangst created signify,
a signing tool built around Daniel Bernstein's Ed25519.

Why might you be interested in signify?

OpenBSD's proven track record of high-quality secure code
Ed25519 delivers strong security (roughly equivalent in strength to 3000-bit RSA according to creator Bernstein)
Ed25519 has a small footprint (signify public keys are only 56 bytes after adding non-Ed25519 data and b64 encoding)
GnuPG doesn't yet officially support digital signatures using ECC (see note below)
You enjoy tinkering with new tools

There are some caveats...

Signify is a signing tool only; It provides no encryption support.
Signify doesn't operate within a PGP-style "web of trust". That said, my hunch is PGP usage is also primarily
trust-on-first-use.
Generated key pairs can be tough to keep organized. Metadata added to keys (64-bit fingerprints and text
comments) helps but a careless user can end up in key hell; be careful.

OK, enough verbiage. Where is it? Well, signify was developed for the OpenBSD community with no plans for a portable
version. So, I downloaded source, made some tweaks, and some coffees later packaged a self-contained Linux port that
is 100% compatible with OpenBSD's signify.

The full Slackware build framework can be found at the slackdepot (if building on other Linuxes get signify-linux.tar.bz2
and optionally get and apply passphrase.diff then make && make install).

Enjoy your signing.

--mancha

----
note: GnuPG does provide ECC support in its development branch (starting with 2.1.0beta2). Supported algorithms
include ECDSA for signing and ECDH to establish a shared secret for encryption key generation, per RFC 6637.

moisespedro · 05-06-2014, 01:00 PM

That is another thing I still get confused about it: GPG, signing keys, etc

ponce · 05-06-2014, 01:18 PM

very interesting: thanks for porting it, mancha!

GazL · 05-06-2014, 01:37 PM

Mancha, is the output of your linux port completely interoperable with keys/signatures created on OpenBSD?

mancha · 05-06-2014, 03:00 PM

ponce: Thanks. I hope you enjoy it.

GazL: Should be 100% inter-operable. Once you build it, try:

Code:

$ wget http://ftp3.usa.openbsd.org/pub/OpenBSD/5.5/SHA256.sig
$ wget http://ftp3.usa.openbsd.org/pub/OpenBSD/src/etc/signify/openbsd-55-base.pub
$ signify -V -e -p openbsd-55-base.pub -m - -x SHA256.sig | tail -n 1

--mancha

j_v · 05-06-2014, 04:39 PM

This is very interesting. Thanks mancha. Your contributions are exemplary.

hitest · 05-06-2014, 06:04 PM

mancha,

Thanks for doing this. I've only just started to use signify on OpenBSD 5.5(May 1st) and I like it a lot.

kooru · 05-07-2014, 01:04 AM

Very interesting. Thanks

JWJones · 05-07-2014, 07:25 AM

Very cool, nice work.

mancha · 05-08-2014, 11:13 PM

Thanks for all the positive feedback!

My port is self-contained so there's no reason it can't be used on other "unixes". In fact, the new version I just uploaded to
SF builds and runs on Cygwin. To reflect this, I'm calling it signify-portable rather than signify-linux.

If you successfully build & use this port on another OS (other than Linux and Cygwin-Windows) let me know and I'll add it to the
list.

I took advantage of this update to sync with upstream (very minor changes) and re-arranged README and BACKGROUND a bit.
The HOWTO remains unchanged and I recommend it for a quick example-driven introduction.

Barring force majeur, I don't plan another release until OpenBSD 5.6 ships.

--mancha

mancha · 05-09-2014, 09:46 AM

I just uploaded signify-portable-20140509.tar.bz2 which fixes a small dangling descriptor bug </OCD>. All you need to get is
the new tarball and edit the SlackBuild to reflect the new version (i.e. 20140509) or re-download signify.SlackBuild.

--mancha

dunric · 05-09-2014, 09:52 AM

Good stuff. Just studying diff to the orig. sources ;-)
Btw. I would welcome and even like to participate on conversion of OpenBSD's LibreSSL to Linux.

mancha · 05-09-2014, 10:48 AM

dunric:

I'm glad you're interested enough to review diffs, that's a great way to learn what I did in my signify porting exercise.

On LibreSSL, I agree with you it's a very interesting project. In fact, I'm actively tracking it and have made a few small contributions.

I've not tried porting it for two reasons: 1) OpenBSD has said they have plans to produce a portable version, and 2) it's still
undergoing so many substantive changes that beginning a port now would be a non-stop effort. That said, I encourage you to look
at what they've done so far if you're interested.

Regarding #1, you will probably be happy to learn OpenBSD is already doing things with a future portable version in mind. There's
another good reason to wait for OpenBSD's portable version: porting LibreSSL can be tricky. It is easy, if you don't really understand
the underlying codebase, to inadvertently undo OpenBSD's improvements or introduce bugs of your own. For example, this
porting effort, already underway, is making decisions I disagree with:

Code:

#include <strings.h>
#define explicit_bzero bzero

The whole point of explicit_bzero is so bzero doesn't get optimized away. That #define effectively neutralizes OpenBSD's improvement.

At some point in the near future, it probably makes sense to start a new thread on this and depending on how things stand maybe
put a group together to look into getting LibreSSL working on Slackware.

--mancha

moisespedro · 05-27-2014, 04:31 PM

It worked flawlessly, thanks mancha

mancha · 09-10-2014, 01:34 AM

I recently sync'd my signify port with OpenBSD. Signify now uses hash tables which should improve performance while the handling
of the prng and secure memory is more robust. I recommend those using my port to upgrade to the latest version:
signify-portable 20140902.

The optional passphrase patch is now bundled in the tarball and can be applied, as before, by setting PASSPHRASE to yes. i.e.

Code:

# PASSPHRASE=yes sh signify.SlackBuild

To build the new version, you need three files:

The project directory also contains SHA256 digest lists signed with my PGP & signify keys for those wishing to verify their downloads.

Enjoy.

--mancha