Usability of WKD

How good does an email client use WKD (to improve crypto usability)

In a bachelor thesis two use cases were developed which describe how users who don't have much experience with encryption can encrypt emails or check signatures with little effort and a good usability.
These use cases are used to name criteria which help developers to improve the usability of their products. They are also useful when it comes to a comparison between the usability of different products.
OpenPGP pubkeys fetched via WKD come with basic trust. See the explanations of the web key directory concept why.

• C1 - Direct method: The product allows fetching pubkeys by the direct method of WKD somehow.
• C2 - Advanced method: The product allows fetching pubkeys somehow, by the preferred, "advanced" method of WKD.
  • Why? - Not all servers are able to offer the Direct method. Implementing both direct and advanced method means a higher chance that users get a key and can use encryption.
• C3 - WKD-ready: ´WKD can be used without any preparations after a clean installation
• C4 - Offered in compose area: WKD is offered in the area where users enter an email-address. To fulfill this criterion it's sufficient that there is a button to start a key lookup. It's not necessary that WKD will be executed automatically. But, users shouldn't have to open additional windows before they can start the lookup.
• C5 - Automatic WKD (Compose): The product uses WKD automatically when users enter an email-address in the area where they can compose an email. The users do not have to press a button to retrieve a key via WKD.
• C6 - Prefer WKD-keys (Compose): When the product has access to keys which were directly imported and don't contain any information about their trust and a WKD-key it should automatically use the WKD-key. This criterion applies to the area to compose an email.
• C7 - Displays basic trust (Compose): The product distinguishes between keys without any information about their trust and WKD-keys that have at least a basic trust. It displays this trust in the area to compose an email.

Advanced features to improve the usability

On this page the basic aspects are explained that should be considered when building WKD into an email client. But there is more what you can do to improve the usability even further.

Usability of different email clients

Multiple email clients offer the feature WKD already. Some of them were tested to check how many of the criteria they fulfill.