Usability of WKD

Criteria for implementing WKD with a good 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.
WKD-keys have a basic trust because they are fetched from WKD-servers that belong to email-providers. Reasons for that are that email-provider know that a pubkey belongs to an email-address and that email-providers usually have a higher security level than private persons who maintain a server. Some criteria reflect this basic trust of WKD-keys.

• C1 - Direct method: The product supports the direct method of WKD
• C2 - Advanced method: The product supports the advanced method of WKD
• C3 - WKD-ready: The product is ready for WKD 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 - Offered in signature area: WKD is offered in the area where users check the signature of an email. Like for C4 users shouldn't have to open additional windows.
• C6 - 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.
• C7 - 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.
• C8 - Prefer WKD-keys (Signature): 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 check the signature of an email.
• C9 - 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.
• C10 - Displays basic trust (Signature): 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 check the signature of an email.

Usability of different products

Balsa

Claws Mail

Evolution

FairEmail

K9Mail

KMail

Mailvelope

GpgOL (Outlook)

Thunderbird