After reading about Google's attempt for end-to-end encryption with PGP keys, I noticed in their FAQ a section about exporting a key generated by their extension for use elsewhere. They say it's possible but that it requires GnuPG 2.1+ wherever you use it.
I had been running 12.04 LTS at the time I generated mine and so my version of gpg was 1.4.x, does that mean I can't import my key into a tool that uses 2.x?
Google's end-to-end encryption plugin makes use of elliptic curve encryption, which is not supported but from GnuPG version 2.1 (and this is still a development version).
But you can go the other way round, and locally create a "normal" RSA key which you can then import to Google's plugin.
Anyway: as the key stays in the plugin, you're at least not giving the private key to Google, but they still can use it for arbitrary operations without you knowing it. What runs inside a web browser is under control of the web site owner, not yours. Better use a mail client (eg. Thunderbird) with a GnuPG addon (eg. Enigmail) and configure it to use your Gmail account – more comfort, more security, better privacy.
Just for the wording: the OpenPGP key version is in both cases v4, but elliptic curves are a rather new encryption algorithm not supported yet by stable GnuPG versions.
That's right, if you have a key generated in End-To-End and want to use it in GnuPG, you have to use version 2.1, which is not officially released yet (still in beta). You can either look for third-party repositories which provide it, or compile it yourself.
Key version matters... I assume the Brian meant to say GnuPG 2.0. GnuPG 2.1 is not packaged for Ubuntu or Debian yet as it is still in beta. One of the new features will be the inclusion of EC25519 keys which may not matter for most of us, but it does offer some significant performance increases.
And other things matter as well. For example the defaults use a SHA1 hash and it should be changed because it has known weaknesses, but it isn't completely broken as is RC4 and perhaps MD5. I highly recommend generating new keys using a stronger hash. See: http://keyring.debian.org/creating-key.html
When I try out Google's End to End I will, as is part my personal PGP policy, only have the subkey on the system. This way I can retain key signatures by revoking, or expiring, the subkey and generate a new one. See: https://wiki.debian.org/Subkeys
I should note the process of managing keys and subkeys could use some significant improvements in terms of usability. And the process of fixing your keys if you generated it with SHA1 hashes is even less fun...
