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Signal 2.0 released with private messaging support

whispersystems.org

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Re: Signal 2.0 released with private messaging support

#11
post #8
post #4

One question I always have with secure systems distributed by app stores, even the open source ones, is how to you verify the source you're reading is the app you're using?

Well, there are several ways to get read access to the iPhone's filesystem. You can grab the binary from the phone and verify that its the same as when you compile the app on your own machine. No one's going to do that for most apps though.

So, I'm not intimately familiar with the code signing process, but I imagine that the bundle on the iPhone wouldn't match the one you would get by compiling the source on your machine.

The former would be signed with Whisper System's distribution certificate, which you couldn't do on your system because you don't have their certificate.

Re: Signal 2.0 released with private messaging support

#13
post #8
post #4

One question I always have with secure systems distributed by app stores, even the open source ones, is how to you verify the source you're reading is the app you're using?

Well, there are several ways to get read access to the iPhone's filesystem. You can grab the binary from the phone and verify that its the same as when you compile the app on your own machine. No one's going to do that for most apps though.

Isn't there chances that different LLVM versions or flags ends up building a slightly different binary ?

Re: Signal 2.0 released with private messaging support

#14
Congrats to the Open WhisperSystems team on this awesome release!

My last gripe (phone call results in only one vibration in vibrate mode), is apparently slated to be fixed in 2.0.2 [1]. Once that's in, there'll be no reason for me to use any other voice/chat app on the iPhone!

Edit: Apparently it's an iOS issue. Filed rdar://20008371. Plz 2 fix it Apple!

[1] https://github.com/WhisperSystems/Signal-iOS/issues/244

Re: Signal 2.0 released with private messaging support

#15
post #4

One question I always have with secure systems distributed by app stores, even the open source ones, is how to you verify the source you're reading is the app you're using?

Google Play Store requires the developer to sign the program with their private key, and only the developer can provide future versions of the program. Moxie from whisper systems seems to trust this system (decentralized signing of binaries) more than the f-droid one (centralized signing of binaries).

There is a very interesting discussion about this on the TextSecure issue queue: https://github.com/WhisperSystems/TextSecure/issues/127

Re: Signal 2.0 released with private messaging support

#17
post #8

Earlier quoted context omitted.

Well, there are several ways to get read access to the iPhone's filesystem. You can grab the binary from the phone and verify that its the same as when you compile the app on your own machine. No one's going to do that for most apps though.

Isn't there chances that different LLVM versions or flags ends up building a slightly different binary ?

And now you are aware of the difficulties in producing reproducible/deterministic builds. This would be a good starting point for further reading: https://wiki.debian.org/ReproducibleBuilds/About

Re: Signal 2.0 released with private messaging support

#19
post #8

Earlier quoted context omitted.

Well, there are several ways to get read access to the iPhone's filesystem. You can grab the binary from the phone and verify that its the same as when you compile the app on your own machine. No one's going to do that for most apps though.

So, I'm not intimately familiar with the code signing process, but I imagine that the bundle on the iPhone wouldn't match the one you would get by compiling the source on your machine. The former would be signed with Whisper System's distribution certificate, which you couldn't do on your system because you don't have their certificate.

Compared to other issues I think stripping/ignoring signatures for comparison should be fairly minor issue.

Re: Signal 2.0 released with private messaging support

#20
Presumably there are still multiple ways for messages to be intercepted from the user's iPhone:

- Physical access or confiscation of the device - Possible backdoor in iOS or the physical iPhone hardware? - Compromise or physical access to a host machine where the user backs up their device.

Although, I'm not sure what can be done to stop this.

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