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    So basically it does trust-on-first-use PGP for email. It’s a bit misleading to say it’s similar to Signal because of the lack of forward/backward secrecy from ratcheting. Also, there’s no support for group chats beyond pairwise encrypting to everyone.

    The main draw seems to be incremental deployment and ease of use, which are admirable goals that many have tried with PGP. Best of luck.

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      Yes, no forward/backward secrecy, which is a serious concern.

      Also, there’s no support for group chats beyond pairwise encrypting to everyone.

      To be fair, that’s all that Signal does for group chats too.

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          I don’t even understand why Signal is making this effort which will require a ton of work to verify this implementation is sound. They could have just done what Threema does:

          In Threema, groups are managed without any involvement of the servers. That is, the servers do not know which groups exist and which users are members of which groups. When a user sends a message to a group, it is individually encrypted and sent to each other group member. This may appear wasteful, but given typical message sizes of 100-300 bytes, the extra traffic is insignificant. Media files (images, video, audio) are en- crypted with a random symmetric key and uploaded only once. The same key, along with a reference to the uploaded file, is then distributed to all members of the group.


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            The new Signal work makes group management secure against a malicious server in addition to reducing the need for pairwise ciphertexts. It prevents old group members from messing with group state (membership, and other metadata), and it allows confidentiality over authenticated access control management.

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              I just don’t see the value. I see an awful lot of complexity though.

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              This is exactly how Signal currently works, FYI.

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                Then why is it changing?

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                  Well you could imagine scenarios where there is logic on the server which infers groups based off of message timing, and then could do things like exclude one person from receiving messages from the group… but I think Signal is fundamentally a dead-end based on its centralized nature anyway…

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        Sooooo … why would I use this over my own preferred email client then?

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          I’ve been using Delta Chat for a while now, and overall it’s my preferred way of chatting with my friends and family. The traditional email clients are just too clunky, especially when someone accidentally starts a new thread by sending a new message instead of replying, or (argh!) sends non-“text/plain” content.

          The chat functionality is on par with popular messengers for my needs—you can receive/send read receipts (if the server supports sending them), send media (e.g. voice messages), and even stream your location in realtime over email. Moreover, encryption works if chat participants use other email client too.

          Note that Delta Chat uses opportunistic encryption by default. There is a feature called “verified groups” that requires encryption, but haven’t tried that yet. Also, at some point they had passwords stored in cleartext, but that should’ve been fixed.

          That said, if you want a secure messenger over email, I’d definitely recommend giving Delta Chat a try. Though it’s not the best choice if you are paranoid.

          Edit: I don’t use Delta Chat exclusively, it does not replace other email clients, but significantly improves chatting experience.

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          love it, but no screenshots on main website and worst… no source code??

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            I do see screenshots on the homepage. Also, it is open source.

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            Link straight to the main website without any interesting technical information: spam.