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OpenPGP, Android and RFC 3676

Now that I own an HTC Evo 4g, I've noticed that email is less than optimal. I blame the screen size, and the lack of good fonts and font sizes, but nonetheless, I've found some annoyances in my life with my Android device, and I'm guessing others are experiencing the same annoyances, be it on their Android, iPhone, Blackberry, or whatever else. Here's the issues I'm facing, and I haven't found any good solutions yet.

OpenPGP on Android
When signing mail using PGP/MIME, some stock mail apps shipped with various phones don't display the text of the email at all. However, signing the mail inline shows the text just fine. This has been reported by a user of a Motorola Droid X, which means that other users are likely having the same issue. The mail comes through as empty with an icon showing attachments. The user must manually download the plain text portion of the mail then open it in an external editor for reading the message. However, even though inline signatures are chatty, they work fine.

I for one can't stand inline signatures. They're ugly as snot, and only end up bothering the recipient to read around your chatty PGP metadata to get to what you actually wrote. It's highly distracting. With PGP/MIME, the signature is sent as an attachment (cough Mutt cough), so the recipient is not bothered by the chatty signature and metadata. Should they wish to verify the integrity of your message, they can download the attachment, and verify it against your public key. If not, they don't need to be concerned with the attachment.

Given the recent problems with the default mail application on Motorola Droid X phones, PGP/MIME is broken. This isn't the first time I've heard this either. Yet, inline always works. I won't send an email without cryptographically signing it, and I highly prefer PGP/MIME attachments. So, should I switch to inline to accommodate users on Droid X phones, and those with other mailers where PGP/MIME is broken? Debating it.

RFC 3676
RFC 3676 states how mailers should handle format=flowed and format=fixed mail. I've always preferred format=fixed, and I've preferred wrapping my mail at 72 characters to allow for a few nested replies before reaching 80 characters in length. Studies have shown that reading lines of text within the 60-100 character width improves accuracy, speed and is less fatiguing than longer, or shorter lines.

However, on mobile devices, the width of the mailer might only be able to accommodate 50-60 characters in width while holding the phone in portrait mode. Thus, the email ends chopped up, and looks quite bad. Rotating my personal phone to landscape fixes this issue, which seems to accommodate around 90 characters. However, there are phones that don't allow for rotating the display from portrait to landscape, and some landscape modes still might not fit the full 80 characters. Thus, the mail remains chopped. Here's an example of what I'm talking about- I'm sure you've seen this before:

Just as an FYI to the list --

On Android's mail application, PGP/MIME attachments are
nigh-unusable.
It won't render even the plaintext portions: it has to be
downloaded and
opened with a text reader. If you're concerned about your
mail being
readable on a mobile device (which is increasingly important
nowadays),
you might want to consider switching to inline signatures.

A fix to this is to change my behavior to format=flowed. When the recipient then reads my mail on the mobile device, the text flows line after line, without choppy line breaks. Of course, the problem with this approach is using mailers on the desktop, where a couple hundred characters could easily fit in the width, thus making the mail more tiring and difficult to read. The desktop user at that point could resize his window to change the width of the mail to give a more pleasurable reading experience.

Either way, format=fixed or format=flowed, one recipient or the other will have to change the width of their mailer to give a better reading experience. It's likely that resizing the desktop mail window is supported by more users than changing the phone to landscape mode. As a result, I'm guessing that I should change the way I compose email to format=flowed.

Conclusion
Given these two outcomes of mobile MUAs, it would appear that cryptographically signing inline and using format=flowed would support the largest audience of recipients, and because smartphones are growing in terms of market share over feature phones, it would make sense to make these changes. However, give the total sample of recipients, what is the percentage of users that are on mobile devices where this is a problem? Am I becoming overly concerned about a minute minority of users?

I'm open to ideas. What should I do? Should I sign inline and use format=flowed for all my mail? I don't like the chatty nature of inline signatures, as already mentioned, but I don't mind changing to format=flowed, although I hate seeing it myself when using Mutt or some other MUA, and the line is forever long.

{ 3 } Comments

  1. BUGabundo using Mozilla Compatible 5.0 on Ubuntu 64 bits | February 25, 2011 at 1:35 pm | Permalink

    i have no prob with my gmail.apk and signed mails!

  2. Aaron using Google Chrome 9.0.597.84 on GNU/Linux 64 bits | February 25, 2011 at 2:12 pm | Permalink

    Well, sure. There are mail clients that support PGP/MIME. The point of the post is, that there are clients that don't handle it correctly, like the Droid X user is suffering from. Of course, not everyone is using Gmail either.

  3. ashley willis using Firefox 11.0 on GNU/Linux 64 bits | April 7, 2012 at 3:52 am | Permalink

    section 4.6 of 3676 states: "Therefore, the use of [OpenPGP] with format=flowed messages is strongly discouraged. [OpenPGP-MIME] is recommended instead." though considering the explanation preceding that statement, it seems to have it backwards (but then i know nothing really of pgp/mime). supporting format=flowed is on my todo list for k-9 mail.

{ 1 } Trackback

  1. Inline shows | ChildrensYogaPlay | March 4, 2011 at 5:20 am | Permalink

    [...] Aaron Toponce : OpenPGP, Android and RFC 3676 [...]

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