[messaging] Transparency for E2E encrypted messaging at a centralized service

[Michael Rogers]

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On 26/03/14 13:17, Tom Ritter wrote:
> In an online-encrypted document sharing model, for the 98%, this
> would look like a document being OpenPGP-encrypted in javascript
> with a symmetric key you choose, and stored online by the service.
> The recipient visits the fileshare, using javascript
> OpenPGP-decrypts the document using the password they received
> out-of-band, and downloads it. For the 2%, they PGP-encrypt the
> document using gpg, and upload it, communicate the secret out of
> band, and the recipient decrypts it using javascript. Or, they
> receive a document encrypted with javascript and download it and
> PGP-decrypt it using gpg.  If you build the service correctly, the
> service won't know ahead of time if the document is going to be
> decrypted in javascript or gpg, and thus can't reliably attack the
> user without a chance of detection.

A nitpick, but does OpenPGP support integrity protection for symmetric
encryption? Last time I looked it just had some kind of hash-based
checksum that the docs warned was not intended to be a real MAC.

Cheers,
Michael


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