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It’s a cool idea but I think it’s hard to imagine how a user would perform this type of messaging transparently. For example, signal doesn’t support bots today

It’s a cool idea but I think it’s hard to imagine how a user would perform this type of messaging transparently. For example, signal doesn’t support bots today or really any kind of unofficial API access so the idea of increasing the number of messengers I need to manually interact with to send a message seems like a big UX burden. As with all things, the simplest UX will probably win. Lastly, if you use a single client like a phone for sending/assembling all of your horcruxes, that’s probably the place that an adversary would target.

ljlolel 6y ago
Let's be more creative here Josh :) Maybe not Signal, but there are multiple secure encrypted email clients which DO have programmatic access including ProtonMail, DeltaChat, and others which are under different jurisdictions around the world. Also you can compile and run your own custom version of the open source Signal Client which does have programmatic access :) >Lastly, if you use a single client like a phone for sending/assembling all of your horcruxes, that’s probably the place that an adversary would target. That vulnerability is listed and described in the doc. It still has security, just a different threat model, just not as much security as using multiple devices. Note that under your one Signal app one device, you have no way to prevent this attack at all. Horcruxes now open up new possibilities.
- maqp 6y ago
  From the documentation: "Often the 0-days are targeting the most common platforms, so using a lesser used platform increases the attack cost linearly or superlinearly." There's only so many platforms. The exploit would either be directed against the app itself or the OS or some other popular software package like SSH server running on the endpoint. The threat model of Horcrux doesn't differ from Signal: both are effectively networked TCBs. This will hold unless you explicitly spec it to run on other systems like airgapped, or split TCB configurations. "Horcruxes now open up new possibilities." What the world needs is less vague marketing language, and more concrete examples.
  - ljlolel 6y ago
    What is TCB? > What the world needs is less vague marketing language, and more concrete examples. Please chill out with the attacks, this is an idea I'm not selling anything. There's a multi-page doc describing it in detail, not vague at all. Threat Models enhancement over Signal described in the doc: ## Threat Model One set of threats this protects agains is any for which people would use Signal for: encrypted security. Also consider the threat in case a Messenger is compelled by the its local government to leak keys on the client (say through an app update) or server by warrant, or there is a rogue employee at Messenger company who compromises. Often a high security environment will compile its own version of Signal's open source client, however it will be days or weeks old and have published vulnerabilities. Horcruxes would allow the high security user to send 1 horcrux on the custom compiled Signal version, and another horcrux on the public app store version (in addition to others), thus increasing the cost significantly of hacking all horcruxes.
    - maqp 6y ago
      "Please chill out with the attacks" I'm not attacking you, just the concept. The goal is not to hurt you, but to protect others. Please don't take it personally! "What is TCB?" https://en.wikipedia.org/wiki/Trusted_computing_base https://en.wikipedia.org/wiki/Trusted_computing_base "One set of threats this protects agains is any for which people would use Signal for: encrypted security." Well, yes, confidentiality is the desired property of encrypted messengers. "Also consider the threat in case a Messenger is compelled by the its local government to leak keys on the client (say through an app update) or server by warrant" I'm not sure what the EARN IT / LAED bill's status is, but for now what holds is US vs Bernstein that established code as speech, and thus protected with 1st amendment, which includes backdoors (effectively compelled speech, also protected under the 1st). Also, Signal has pledged to move abroad if the bills pass. Given that the clients are reproducible and FOSS, I'm going to take any claim that the US government can just force a die-hard cypherpunk like Moxie to add a backdoor and keep that quiet with all his contacts at the ACLU and thee EFF, with a truck-load of salt. "rogue employee at Messenger company who compromises." The git tree is a rather permanent log for who merges a backdoor into the code. Also, there's most likely some form of code review especially wrt security critical code. "Often a high security environment will compile its own version of Signal's open source client" Citation needed. Also, why wouldn't the independently compiled client also update itself automatically via Signal's servers? It's not like the APK version (https://signal.org/android/apk/ https://signal.org/android/apk/) doesn't also update itself. "Horcruxes would allow the high security user to send 1 horcrux on the custom compiled Signal version, and another horcrux on the public app store version" The thing is, Signal can only be compromised by hacking the endpoint, as can Horcrux. If you're relying on the secrecy of the CT delivery mechanisms, you're essentially attempting security through obscurity that only adds log2(n) bits of security where n is the number of possible delivery paths.

ljlolel 6y ago

Let's be more creative here Josh :) Maybe not Signal, but there are multiple secure encrypted email clients which DO have programmatic access including ProtonMail, DeltaChat, and others which are under different jurisdictions around the world. Also you can compile and run your own custom version of the open source Signal Client which does have programmatic access :) >Lastly, if you use a single client like a phone for sending/assembling all of your horcruxes, that’s probably the place that an adversary would target. That vulnerability is listed and described in the doc. It still has security, just a different threat model, just not as much security as using multiple devices. Note that under your one Signal app one device, you have no way to prevent this attack at all. Horcruxes now open up new possibilities.

maqp 6y ago
From the documentation: "Often the 0-days are targeting the most common platforms, so using a lesser used platform increases the attack cost linearly or superlinearly." There's only so many platforms. The exploit would either be directed against the app itself or the OS or some other popular software package like SSH server running on the endpoint. The threat model of Horcrux doesn't differ from Signal: both are effectively networked TCBs. This will hold unless you explicitly spec it to run on other systems like airgapped, or split TCB configurations. "Horcruxes now open up new possibilities." What the world needs is less vague marketing language, and more concrete examples.
- ljlolel 6y ago
  What is TCB? > What the world needs is less vague marketing language, and more concrete examples. Please chill out with the attacks, this is an idea I'm not selling anything. There's a multi-page doc describing it in detail, not vague at all. Threat Models enhancement over Signal described in the doc: ## Threat Model One set of threats this protects agains is any for which people would use Signal for: encrypted security. Also consider the threat in case a Messenger is compelled by the its local government to leak keys on the client (say through an app update) or server by warrant, or there is a rogue employee at Messenger company who compromises. Often a high security environment will compile its own version of Signal's open source client, however it will be days or weeks old and have published vulnerabilities. Horcruxes would allow the high security user to send 1 horcrux on the custom compiled Signal version, and another horcrux on the public app store version (in addition to others), thus increasing the cost significantly of hacking all horcruxes.
  - maqp 6y ago
    "Please chill out with the attacks" I'm not attacking you, just the concept. The goal is not to hurt you, but to protect others. Please don't take it personally! "What is TCB?" https://en.wikipedia.org/wiki/Trusted_computing_base https://en.wikipedia.org/wiki/Trusted_computing_base "One set of threats this protects agains is any for which people would use Signal for: encrypted security." Well, yes, confidentiality is the desired property of encrypted messengers. "Also consider the threat in case a Messenger is compelled by the its local government to leak keys on the client (say through an app update) or server by warrant" I'm not sure what the EARN IT / LAED bill's status is, but for now what holds is US vs Bernstein that established code as speech, and thus protected with 1st amendment, which includes backdoors (effectively compelled speech, also protected under the 1st). Also, Signal has pledged to move abroad if the bills pass. Given that the clients are reproducible and FOSS, I'm going to take any claim that the US government can just force a die-hard cypherpunk like Moxie to add a backdoor and keep that quiet with all his contacts at the ACLU and thee EFF, with a truck-load of salt. "rogue employee at Messenger company who compromises." The git tree is a rather permanent log for who merges a backdoor into the code. Also, there's most likely some form of code review especially wrt security critical code. "Often a high security environment will compile its own version of Signal's open source client" Citation needed. Also, why wouldn't the independently compiled client also update itself automatically via Signal's servers? It's not like the APK version (https://signal.org/android/apk/ https://signal.org/android/apk/) doesn't also update itself. "Horcruxes would allow the high security user to send 1 horcrux on the custom compiled Signal version, and another horcrux on the public app store version" The thing is, Signal can only be compromised by hacking the endpoint, as can Horcrux. If you're relying on the secrecy of the CT delivery mechanisms, you're essentially attempting security through obscurity that only adds log2(n) bits of security where n is the number of possible delivery paths.