Ask HN: browser extension to encrypt emails in gmail client-side

7 points by rheide ↗ HN
Hey everyone, I was wondering if anyone knows of a browser extension that hooks into the gmail interface and can encrypt the contents of an email before sending it.

It's always a problem to make security available for the masses (and actually secure!). Here's how I'd do it if I had to set one up.

The Chrome extension would prevent gmail from reading the email fields, preventing the saving of drafts server-side. On sending the email it would encrypt the content with a key that is unique per receiving address. If the client has the extension installed it can decrypt the contents automatically on display.

The problem is getting the decryption key across to the recipient securely, but that only has to be done once. After that the browser extension can hold it indefinitely. It could be done with a trusted third party site, which only holds the key for a very short time, and only for the first email sent to a new recipient. Power users could of course use their own ways of getting keys across.

58 comments

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You'd be better off using a non-gmail service with this sort of privacy requirement anticipated. Gmail is a pretty uninspiring service to use fully encrypted.
I agree, but I have to disagree. I'd gladly use a more secure email service, but the problem is: 99% of everyone I know uses gmail or Google Apps. It doesn't matter if I encrypt my email if everyone I communicate with is vulnerable. The trick is getting the layman to accept something simple like a browser extension. If even 20% of the people I communicate with would consider using the extension I would be very happy.
The trick is to reduce the threat surface, not to do whats right all the time, removing gmail from your side makes your threat surface lower. Browser extensions don't provide security, and its unlikely that chrome would be immune to google-wide spying programs.
That's a good point actually. Chrome would be just as vulnerable as gmail..
WebPG or Cr-gpg perhaps can handle the GPG part probably.

I'm not so sure about the not saving Drafts, that would require rewriting some bits of Javascript which might break other stuff.

As for key exchange, that shouldn't be handle by an extension. If you want to encrypt your e-mail so the other party can read it, encrypt it with their public key, which by definition is public and can be uploaded to a keyserver.

Since the public key is public, any eavesdroppers will also be able to read the email. There is no point in the extension if you use the recipient's public key. It must be a mutually agreed secret.
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Am I missing something subtle ? With a public key, you should be able only to write mails, not read them, right ?
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Email encrypted with the recipient's public key can only be decrypted by recipient's private key.

It is the most secure way to send an encrypted email.