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if this is true. Then why the hell does rohde & schwarz sell imsi catcher that cost 100000+ to police. I understand that the carrier always knows where a phone number is located. But in germany you can still buy anonymous sim cards.

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Nuttso

@Nuttso2go

Jan 25, 2019

Replying to @Nuttso2go and @DanielMicay

For example you are a journalist in some shady democracy and they decide to investigate you. Like to get your phone number. If you are with a burner number the telco doesn't have it tied to your name. So when they wan't to track you. They have to use an imsi catcher first

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In practice, most people use lots of unencrypted calls and messages. That's why I clearly recommended using encrypted calls and messages. It doesn't even need to be end-to-end encrypted to counter this. Transport layer encryption with pinning is more than enough to counter this.

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An 'anonymous' SIM card is not going to stay anonymous for long if you are actually being targeted. They can correlate it with your location and start tracking you directly once they've identified your phone. I don't understand why you think IMSI catchers are a counter to that.

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If they have access to the carriers, they can see which devices are active in your house or where they know you go, and then figure out which one is your phone. Local interception mostly serves the purpose of bypassing working through carriers, if they don't have that access.

10:14 AM · Jan 25, 2019Twitter Web Client

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so this would only be used for unlawful tracking. But I got it. There is no real value adding this to the OS and lowering security with it.

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They want those devices to intercept *unencrypted* data without getting warrants. In many cases, companies grant access without a warrant anyway. The solution is not sending / receiving sensitive unencrypted data. The carrier has access no matter what and likely logs it all.

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and

The network / carrier should not be trusted in the first place. Local interception doesn't change any of the threat models. The authentication / encryption of the network has little value as it isn't trusted and so many people have access to the point it's nearly public info.

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and

There has been leaked bulk SMS history for many people, making the data public. That's how it should be treated. You shouldn't be doing anything over those channels where it even matters if that traffic is intercepted, since it's already logged with many people having access.