I'm developing a firefox extension and I'd like to provide automatic update to my beta-testers (who are not tech-savvy). Unfortunately, the update server doesn't provide HTTPS. According to the [Extension Developer Guide on signing updates](https://developer.mozilla.org/en/Extension_Versioning,_Update_and_Compatibility#Signing_Update_Manifests), I have to sign my update.rdf and provide an encoded public key in the install.rdf.

There is the [McCoy](https://developer.mozilla.org/en/McCoy) tool to [do all of this](http://www.borngeek.com/firefox/automatic-firefox-extension-updates/), but it is an interactive GUI tool and I'd like to automate the extension packaging using an Ant script (as this is part of a much bigger process). I can't find a more precise description of what's happening to sign the update.rdf manifest than below, and McCoy source is an awful lot of javascript.

The doc says:

> 
> The add-on author creates a public/private RSA cryptographic key pair. The public part of the key is DER encoded and then base 64 encoded and added to the add-on's install.rdf as an updateKey entry.
> 
> 
> (...)
> 
> 
> Roughly speaking the update information is converted to a string, then hashed using a sha512 hashing algorithm and this hash is signed using the private key. The resultant data is DER encoded then base 64 encoded for inclusion in the update.rdf as an signature entry.
> 
> 
> 

I don't know well about DER encoding, but it seems like it needs some parameters.

So would anyone know

* either the full algortihm to sign the update.rdf and install.rdf using a predefined keypair, or a scriptable alternative to McCoy
* whether a command-line tool like [asn1coding](http://linux.die.net/man/1/asn1coding) will suffise
* a good/simple developer tutorial on DER encoding