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Thanks for the laugh, you should write news title it would be fun! Anyway the problem of Signal is that you have to use your phone number and a phone number is

Thanks for the laugh, you should write news title it would be fun! Anyway the problem of Signal is that you have to use your phone number and a phone number is a much stronger link to you than an ip for example. As the ex boss of NSA said "We Kill People Based on Metadata".

infosechandbook 5y ago
> Anyway the problem of Signal is that you have to use your phone number and a phone number is a much stronger link to you than an ip for example. Signal requires access to a valid phone number during registration, not "your phone number." It can even be a virtual/landline/temporary phone number without any SIM cards or cell phones involved. How is this a "much stronger link to you than an ip"? And how about looking at more than just an isolated property of a competitor? > As the ex boss of NSA said "We Kill People Based on Metadata". XMPP servers are a gold mine when it comes to metadata.
- zaik 5y ago
  > It can even be a virtual/landline/temporary phone number without any SIM cards or cell phones involved. Then contact discovery would not work, which is the main advantage of collecting the phone number in the first place. How many of your contacts who use Signal used their real phone number? > XMPP servers are a gold mine when it comes to metadata. Then even more so for Signal, since metadata for all users can be collected by a single entity. This is not possible in a federated network like XMPP.
  - infosechandbook 5y ago
    > How many of your contacts who use Signal used their real phone number? Most of them; however, there is no obligation to provide any personal data when registering a SIM card in my country. Even if providing personal data would be mandatory and if we assume that telcom providers track us all the time, then it doesn't mean that this data is accessible to the organization behind an instant messaging service. > Then even more so for Signal, since metadata for all users can be collected by a single entity. This is not possible in a federated network like XMPP. This ignores that Signal and XMPP don't process the same amount of metadata in the first place, and the de-facto centralization of the XMPP network (also stated in our article -> the majority of XMPP users only uses a small number of public XMPP instances, and these XMPP instances are hosted by a tiny number of companies in mainly three countries on this planet).
  - rakoo 5y ago
    > Then contact discovery would not work, which is the main advantage of collecting the phone number in the first place. I believe the real reason Signal requires a phone number is that it is a pretty good anti-spam filter
tialaramex 5y ago
But I already have a phone number. My friends already know my phone number. If I instead got a "nickname" it would be tialaramex of course, which is even more identifying than my phone number. If I chose a deliberate random pseudonymous "nickname" to avoid "metadata" - then nobody can contact me, what use is that? The NSA may "kill people based on metadata" but XMPP produces far more metadata for such decisions than Signal. XMPP encourages people to build clique servers, which fail a key security requirement "Don't Stand Out". The six other users of "Bob's 100% Preparedness Militia and True Patriots Server" may be quite sure Bob is trustworthy and won't rat on them, and maybe one of them only uses it to post funny GIFs of cats, but the loose metadata association between this group and a plot to kidnap a State Senator means all seven of them are targets anyway. But if you try not to stand out by using a popular server, that server's operators have far more insight into you than Signal's server operators do. Remember, when my friend Steve sent me a Signal message last week, Signal does not know who sent that. I know, because I decrypted the message, but Signal does not. That's a bunch of heavy cryptographic lifting, but from their point of view it was worth it to improve privacy.
- zaik 5y ago
  > Remember, when my friend Steve sent me a Signal message last week, Signal does not know who sent that. This seems wrong. How could the Signal server have relayed the message from Steve to you if it does not know the recipient?
  - MattJ100 5y ago
    They have a feature called "sealed sender"[1]. Your Signal client authenticates to a Signal service that verifies you, and then signs and issues a certificate that you can use to vouch for your identity. Then, you can encrypt this certificate as part of your message. Then ask Signal to deliver your message to the recipient. The Signal server won't be able to tell the recipient the account that the message is from, but after the recipient decrypts the message they will see the signed certificate and know it was you. The problem with this is, Signal is centralized and they see the both the IP address (and other metadata) when you contact them to obtain the certificate and they they also see the IP address you send the message from. Correlation between the two Signal-operated services would reveal your identity. Unfortunately we, as users, have no way to know that this is not happening. [1]: https://signal.org/blog/sealed-sender/ https://signal.org/blog/sealed-sender/
tptacek 5y ago
You think you're making an argument against Signal, but you're in fact making the argument for it. The reason Signal deals in your phone number is precisely to keep them from managing databases of metadata about who's talking to who; the phone numbers keeps the social graph on the clientside. Go look at RFC6121 Section 2 for one example of this. The point of Signal's design is that the server can't facilitate this kind of transaction, because it's unsafe for the server to keep that data in plaintext.

infosechandbook 5y ago

> Anyway the problem of Signal is that you have to use your phone number and a phone number is a much stronger link to you than an ip for example. Signal requires access to a valid phone number during registration, not "your phone number." It can even be a virtual/landline/temporary phone number without any SIM cards or cell phones involved. How is this a "much stronger link to you than an ip"? And how about looking at more than just an isolated property of a competitor? > As the ex boss of NSA said "We Kill People Based on Metadata". XMPP servers are a gold mine when it comes to metadata.

zaik 5y ago
> It can even be a virtual/landline/temporary phone number without any SIM cards or cell phones involved. Then contact discovery would not work, which is the main advantage of collecting the phone number in the first place. How many of your contacts who use Signal used their real phone number? > XMPP servers are a gold mine when it comes to metadata. Then even more so for Signal, since metadata for all users can be collected by a single entity. This is not possible in a federated network like XMPP.
- infosechandbook 5y ago
  > How many of your contacts who use Signal used their real phone number? Most of them; however, there is no obligation to provide any personal data when registering a SIM card in my country. Even if providing personal data would be mandatory and if we assume that telcom providers track us all the time, then it doesn't mean that this data is accessible to the organization behind an instant messaging service. > Then even more so for Signal, since metadata for all users can be collected by a single entity. This is not possible in a federated network like XMPP. This ignores that Signal and XMPP don't process the same amount of metadata in the first place, and the de-facto centralization of the XMPP network (also stated in our article -> the majority of XMPP users only uses a small number of public XMPP instances, and these XMPP instances are hosted by a tiny number of companies in mainly three countries on this planet).
- rakoo 5y ago
  > Then contact discovery would not work, which is the main advantage of collecting the phone number in the first place. I believe the real reason Signal requires a phone number is that it is a pretty good anti-spam filter

tialaramex 5y ago

But I already have a phone number. My friends already know my phone number. If I instead got a "nickname" it would be tialaramex of course, which is even more identifying than my phone number. If I chose a deliberate random pseudonymous "nickname" to avoid "metadata" - then nobody can contact me, what use is that? The NSA may "kill people based on metadata" but XMPP produces far more metadata for such decisions than Signal. XMPP encourages people to build clique servers, which fail a key security requirement "Don't Stand Out". The six other users of "Bob's 100% Preparedness Militia and True Patriots Server" may be quite sure Bob is trustworthy and won't rat on them, and maybe one of them only uses it to post funny GIFs of cats, but the loose metadata association between this group and a plot to kidnap a State Senator means all seven of them are targets anyway. But if you try not to stand out by using a popular server, that server's operators have far more insight into you than Signal's server operators do. Remember, when my friend Steve sent me a Signal message last week, Signal does not know who sent that. I know, because I decrypted the message, but Signal does not. That's a bunch of heavy cryptographic lifting, but from their point of view it was worth it to improve privacy.

zaik 5y ago
> Remember, when my friend Steve sent me a Signal message last week, Signal does not know who sent that. This seems wrong. How could the Signal server have relayed the message from Steve to you if it does not know the recipient?
- MattJ100 5y ago
  They have a feature called "sealed sender"[1]. Your Signal client authenticates to a Signal service that verifies you, and then signs and issues a certificate that you can use to vouch for your identity. Then, you can encrypt this certificate as part of your message. Then ask Signal to deliver your message to the recipient. The Signal server won't be able to tell the recipient the account that the message is from, but after the recipient decrypts the message they will see the signed certificate and know it was you. The problem with this is, Signal is centralized and they see the both the IP address (and other metadata) when you contact them to obtain the certificate and they they also see the IP address you send the message from. Correlation between the two Signal-operated services would reveal your identity. Unfortunately we, as users, have no way to know that this is not happening. [1]: https://signal.org/blog/sealed-sender/ https://signal.org/blog/sealed-sender/

tptacek 5y ago

You think you're making an argument against Signal, but you're in fact making the argument for it. The reason Signal deals in your phone number is precisely to keep them from managing databases of metadata about who's talking to who; the phone numbers keeps the social graph on the clientside. Go look at RFC6121 Section 2 for one example of this. The point of Signal's design is that the server can't facilitate this kind of transaction, because it's unsafe for the server to keep that data in plaintext.