23.104. DD 103: HTTPS Links for Wallet Actions

Design status:

Draft

Implementation status:

Not started

DD shepherd:

Florian Dold

Historical contributors:

Florian Dold

First published:

2026-09-07

Last substantive change:

2026-09-07

23.104.1. Summary

This design document proposes using https:// URLs as a fallback for taler:// URIs.

23.104.2. Motivation

Some users of the Taler wallet have reported that applications they use don’t support taler:// URIs nicely. Some applications don’t render them correctly, linking only the second part (after the taler://) as a link, which then usually leads them to an invalid page.

23.104.3. Requirements

• The solution should still allow alternative implementations of the wallet not provided by the Taler project.

23.104.4. Proposed Solution

In addition to taler:// URIs, wallets also register themselves as handlers for https://wallet.taler.net/#. The taler action is provided after the #. These https:// URLs are directly mapped to taler:// URIs and interpreted by the wallet:

The following URLs

• https://wallet.taler.net/#taler://${action}/${rest}

• https://wallet.taler.net/#/${action}/${rest}

• https://wallet.taler.net/#${action}/${rest}

are all mapped to taler://${action}/${rest}.

23.104.5. Security Considerations

• Since the payload of the encoded Taler action is in the fragment of the https:// URL, navigating to the URL does not send any data from the Taler action to the server.

• If https:/wallet.taler.net/ is compromised, an attacker can intercept taler:// URIs on a devices that does not already have a wallet installed.

• Using https://wallet.taler.net/ links consistently on Websites would allow the WebExtension wallet to run with considerably less broad permissions.

23.104.6. Ecosystem Considerations

• We can allow developers of alternative Taler wallets to register themselves on Android / iOS.

• For F-Droid, packages are signed with the F-Droid key anyway, so allowing this key to handle https://wallet.taler.net/ would allow alternative Taler wallet implementations on F-Droid automatically.

23.104.7. Alternatives

• Push for widespread adoption of taler:// URI support.

• That’s what would happen in an ideal world, and we should still push for it.

• Use the domain of exchanges to encode Taler actions, e.g. https://exchange.taler-ops.ch/#pay/....

  • This requires trusting more servers

  • It leads to an NxM issues where N wallets would need to apply at M exchanges to be allowed to register as a handler for their URL.

23.104.8. Discussion / Q&A

• Why use https://wallet.taler.net/?

  • The link is easily recognizeable as a link for the Taler wallet.

  • When no wallet is installed, this is exactly the location we want the user to be navigated to, as it asks the user to install a wallet

  • Since wallet.taler.net is owned by the Taler project and links to the wallets, they can be considered part of the same trust domain.