Armory also has it in the todo list.
It's expected within months since last year
LOL yeah! I remember Reiner saying that in an LTB podcast. TBF he did say it was difficult to include that in the GUI in a user friendly way.
It might just happen with Electrum, though. Co-signing multi-sig transactions is how the Electrum developer plans to monetize his software. He's founded a startup around Electrum:
4. A 2-factor authentication service using multisig addresses is under development, that will be available in Electrum through a paying plugin. I made a demonstration of that service in Barcelona last fall, during the meeting organized by genjix. I am now working with lawyers, in order to define the terms of use for that service.
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