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I had a family member working in Tibet with Christian churches, which is a very sensitive topic in China. Most all technology was outright blocked (except overt

I had a family member working in Tibet with Christian churches, which is a very sensitive topic in China. Most all technology was outright blocked (except overtly monitored wechat). However, Signal was not blocked by the great firewall and we were able to communicate freely on it. But now I'm wondering why isn't Signal blocked? Does the CCP have a backdoor into it somehow and therefore doesn't feel threatened by it?

colmmacc 2y ago
I very much doubt that the CCP has a backdoor into Signal the app; but it is worth keeping in mind that if an actor can observe traffic, e.g. cellular traffic records or network flow logs, they may be able to correlate senders and receivers through ordinary time-stamps. Person A sends 200 bytes at time T, Person B receives 200 bytes at time T + 300ms. It doesn't take much analysis to build up a picture of a weighted network of communicators. There are "Military Grade" message and voice encryption technologies that avoid these issues by always sending a fixed amount of traffic to all parties, but that tends to be impractical for mobile apps.
ikmckenz 2y ago
What year was this? Signal has been blocked by the GFW for several years now. Here’s an article from 2021: https://www.nbcnews.com/tech/tech-news/encrypted-messaging-app-signal-blocked-china-rcna432 https://www.nbcnews.com/tech/tech-news/encrypted-messaging-a...
- Tmpod 2y ago
  Signal has a toggle for censorship resistant routing, if I'm not mistaken. I believe it works quite well in most places, including China?
- declan_roberts 2y ago
  Pre-covid, so that checks out.
rnhmjoj 2y ago
The easiest explanation is no significant amount of people in China are using it, there's no need to resort to conspiracies and backdoors.
- canadiantim 2y ago
  I think the easiest explanation here is that it actually does have a backdoor, hence being allowed to stay.
  - Ringz 2y ago
    Thank god, this is not and never was the easiest explanation. https://news.ycombinator.com/item?id=41382342 https://news.ycombinator.com/item?id=41382342
    - canadiantim 2y ago
      If China was allowing Signal to operate within China, the most logical and simple explanation would have been that China had backdoor access. To you point though, it sounds like Signal is not actually allowed to operate in China so there's nothing to explain after all.
      - ithkuil 2y ago
        "Not being able to operate" is not equal to "it won't work if you already have an account". As long as the average Chinese citizen cannot effectively create an account (because the activation SMS cannot reach their phones) the Chinese government may allow existing users of signal (who activated the account abroad) to communicate with signal.
        b112 2y ago
        Signal may also be a "signal" that the state should look more closely at a person. With so few users, if the user is up to no good, as per the state's view, just knowing to watch them is helpful.
barbwire24 2y ago
It is blocked. Its activation SMS had been blocked for quite a while. Same happened for the connection to signal servers. Early this year, Apple also removed signal from China Appstore.
- amatecha 2y ago
  Vouched for this because at least one of the claims in the message is true: https://www.wsj.com/tech/apple-removes-whatsapp-threads-from-china-app-store-on-government-orders-a0c02100 https://www.wsj.com/tech/apple-removes-whatsapp-threads-from...

colmmacc 2y ago

I very much doubt that the CCP has a backdoor into Signal the app; but it is worth keeping in mind that if an actor can observe traffic, e.g. cellular traffic records or network flow logs, they may be able to correlate senders and receivers through ordinary time-stamps. Person A sends 200 bytes at time T, Person B receives 200 bytes at time T + 300ms. It doesn't take much analysis to build up a picture of a weighted network of communicators. There are "Military Grade" message and voice encryption technologies that avoid these issues by always sending a fixed amount of traffic to all parties, but that tends to be impractical for mobile apps.

ikmckenz 2y ago

What year was this? Signal has been blocked by the GFW for several years now. Here’s an article from 2021: https://www.nbcnews.com/tech/tech-news/encrypted-messaging-app-signal-blocked-china-rcna432 https://www.nbcnews.com/tech/tech-news/encrypted-messaging-a...

Tmpod 2y ago
Signal has a toggle for censorship resistant routing, if I'm not mistaken. I believe it works quite well in most places, including China?
declan_roberts 2y ago
Pre-covid, so that checks out.

rnhmjoj 2y ago

The easiest explanation is no significant amount of people in China are using it, there's no need to resort to conspiracies and backdoors.

canadiantim 2y ago
I think the easiest explanation here is that it actually does have a backdoor, hence being allowed to stay.
- Ringz 2y ago
  Thank god, this is not and never was the easiest explanation. https://news.ycombinator.com/item?id=41382342 https://news.ycombinator.com/item?id=41382342
  - canadiantim 2y ago
    If China was allowing Signal to operate within China, the most logical and simple explanation would have been that China had backdoor access. To you point though, it sounds like Signal is not actually allowed to operate in China so there's nothing to explain after all.
    - ithkuil 2y ago
      "Not being able to operate" is not equal to "it won't work if you already have an account". As long as the average Chinese citizen cannot effectively create an account (because the activation SMS cannot reach their phones) the Chinese government may allow existing users of signal (who activated the account abroad) to communicate with signal.
      - b112 2y ago
        Signal may also be a "signal" that the state should look more closely at a person. With so few users, if the user is up to no good, as per the state's view, just knowing to watch them is helpful.

barbwire24 2y ago

It is blocked. Its activation SMS had been blocked for quite a while. Same happened for the connection to signal servers. Early this year, Apple also removed signal from China Appstore.

amatecha 2y ago
Vouched for this because at least one of the claims in the message is true: https://www.wsj.com/tech/apple-removes-whatsapp-threads-from-china-app-store-on-government-orders-a0c02100 https://www.wsj.com/tech/apple-removes-whatsapp-threads-from...