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> It still won't prevent someone invading privacy if they have physical access to your device, since the identities are stored locally for your usage convenienc

> It still won't prevent someone invading privacy if they have physical access to your device, since the identities are stored locally for your usage convenience. does it mean if a lot of Simplex users band together and sift through all their local identities they can connect the dots?

ajani 3y ago
Let's say the whole network is just 4 nodes. A, B, C, D. And A and B are connected. And C and D are connected. And I have physical access to all 4 devices. In phone A, you will have B's contact stored locally, let's say as "Dan". B, A, "Pedro" C, D, "Dan" (yes D is also named "Dan") D, C, "Olga" What do you look for?
- tyingq 3y ago
  It's a little hard to grok the details, but it sounds like it's a collection of "dead drops". Like, if done in a physical way, imagine locations around a city where you can drop off scraps of paper with cipher encoded message on them. Encoded not just with sender/recipient keys, but a dead drop location specific key too. And an agreement that replies to a received message get dropped off at a different, randomly selected one. Everyone can see and read the cipher text on all the papers, but each of the 4 people can only decode the things meant for them. So, if that's how it works, you could certainly learn who was talking to who if you had access to all the devices. But access to one device only shows you what came and went to the device, but no data about which of the other three users were involved in those reads/writes. You would have to gain access to each device, in turn, to prove whether it was in contact with the first device.
  - epoberezkin 3y ago
    That's right. With the difference that you drop at one address, and another address has to be used for the pickup. Disclaimer: I'm the founder.
    - deleted 3y ago
      [deleted]
  - throwaway290 3y ago
    > But access to one device only I specifically said a lot of users. A lot is the opposite of one. Imagine a lot (>40% of total users) of impostor devices acting in accord to deanonymize some of the X and Y. Is it vulnerable to that. Like apparently Tor is.
    - ajani 3y ago
      No. It wouldn’t be vulnerable to that. You would at most be able to deanonymize a certain percentage within the impostor network itself. Kind of pointless. Physical access of devices is the only way to have some chance of deanonymizing some of the users (always less than number of devices you have access to). That’s my understanding, but the maker of this thing is here, and maybe can respond better?
    - deleted 3y ago
      [deleted]
  - account-5 3y ago
    Thanks this made it clear for me how it works, and with the confirmation of the founder I'm happy I can understand it.
- deleted 3y ago
  [deleted]
OJFord 3y ago
They really bury the detail IMO after the banner claim front and centre on the website (I guess because it's hard/awkward to explain without it sounding just like a difference in nomenclature). What makes it work afaict is the combination of: - there are still queue (inbox) IDs - key (and (just initial?) queue ID) exchange out of band https://github.com/simplex-chat/simplexmq/blob/stable/protocol/overview-tjr.md#simplex-messaging-protocol https://github.com/simplex-chat/simplexmq/blob/stable/protoc... So messages are still delivered to an identifier, it's just that every user has tonnes of identifiers (per contact/group), there's no server tracking and handling their exchange, and possibly they rotate via encrypted messages once established anyway. Exchanging out of band gets you the secrecy, and having one per-chat protects you from a contact turning out bad/leaking/compromised - it's fine that they have metadata about their own chat with you, because they have that & the plaintext anyway.
- ajani 3y ago
  You are missing a crucial aspect of this. There is no identifier. Only a connection. An identifier is something that relates to more than one thing. A connection is its two endpoints. It is those ends. Who is at each end is unknown and cannot be known without resorting to grabbing all users devices.
  - largbae 3y ago
    That isn't what GP is saying. In order to effectively use the chat, you are going to tag that connection identifier with a name like Joe on your endpoint device, so that when a message comes in you remember this was the conversation with Joe. The server may not know that this is you and Joe, but you do.
    - account-5 3y ago
      Yeah, that was my take. The issue with end to end encryption is the ends. The ends are the weak link. I think though that simplex may be the best option in this regard though. The user has to know who they are speaking with, but here the user can choose not to tag the connection, and therefore take on the mental load of remembering which connection identifier referred to which person. Having not used this chat I don't know how easy thing might be but I do remember, before mobile phones were a thing, being able to remember at least 8 phone numbers that I used to call regularly. Certainly if it called for it you could do this with simplex?

ajani 3y ago

Let's say the whole network is just 4 nodes. A, B, C, D. And A and B are connected. And C and D are connected. And I have physical access to all 4 devices. In phone A, you will have B's contact stored locally, let's say as "Dan". B, A, "Pedro" C, D, "Dan" (yes D is also named "Dan") D, C, "Olga" What do you look for?

tyingq 3y ago
It's a little hard to grok the details, but it sounds like it's a collection of "dead drops". Like, if done in a physical way, imagine locations around a city where you can drop off scraps of paper with cipher encoded message on them. Encoded not just with sender/recipient keys, but a dead drop location specific key too. And an agreement that replies to a received message get dropped off at a different, randomly selected one. Everyone can see and read the cipher text on all the papers, but each of the 4 people can only decode the things meant for them. So, if that's how it works, you could certainly learn who was talking to who if you had access to all the devices. But access to one device only shows you what came and went to the device, but no data about which of the other three users were involved in those reads/writes. You would have to gain access to each device, in turn, to prove whether it was in contact with the first device.
- epoberezkin 3y ago
  That's right. With the difference that you drop at one address, and another address has to be used for the pickup. Disclaimer: I'm the founder.
  - deleted 3y ago
    [deleted]
- throwaway290 3y ago
  > But access to one device only I specifically said a lot of users. A lot is the opposite of one. Imagine a lot (>40% of total users) of impostor devices acting in accord to deanonymize some of the X and Y. Is it vulnerable to that. Like apparently Tor is.
  - ajani 3y ago
    No. It wouldn’t be vulnerable to that. You would at most be able to deanonymize a certain percentage within the impostor network itself. Kind of pointless. Physical access of devices is the only way to have some chance of deanonymizing some of the users (always less than number of devices you have access to). That’s my understanding, but the maker of this thing is here, and maybe can respond better?
  - deleted 3y ago
    [deleted]
- account-5 3y ago
  Thanks this made it clear for me how it works, and with the confirmation of the founder I'm happy I can understand it.
deleted 3y ago
[deleted]

OJFord 3y ago

They really bury the detail IMO after the banner claim front and centre on the website (I guess because it's hard/awkward to explain without it sounding just like a difference in nomenclature). What makes it work afaict is the combination of: - there are still queue (inbox) IDs - key (and (just initial?) queue ID) exchange out of band https://github.com/simplex-chat/simplexmq/blob/stable/protocol/overview-tjr.md#simplex-messaging-protocol https://github.com/simplex-chat/simplexmq/blob/stable/protoc... So messages are still delivered to an identifier, it's just that every user has tonnes of identifiers (per contact/group), there's no server tracking and handling their exchange, and possibly they rotate via encrypted messages once established anyway. Exchanging out of band gets you the secrecy, and having one per-chat protects you from a contact turning out bad/leaking/compromised - it's fine that they have metadata about their own chat with you, because they have that & the plaintext anyway.

ajani 3y ago
You are missing a crucial aspect of this. There is no identifier. Only a connection. An identifier is something that relates to more than one thing. A connection is its two endpoints. It is those ends. Who is at each end is unknown and cannot be known without resorting to grabbing all users devices.
- largbae 3y ago
  That isn't what GP is saying. In order to effectively use the chat, you are going to tag that connection identifier with a name like Joe on your endpoint device, so that when a message comes in you remember this was the conversation with Joe. The server may not know that this is you and Joe, but you do.
  - account-5 3y ago
    Yeah, that was my take. The issue with end to end encryption is the ends. The ends are the weak link. I think though that simplex may be the best option in this regard though. The user has to know who they are speaking with, but here the user can choose not to tag the connection, and therefore take on the mental load of remembering which connection identifier referred to which person. Having not used this chat I don't know how easy thing might be but I do remember, before mobile phones were a thing, being able to remember at least 8 phone numbers that I used to call regularly. Certainly if it called for it you could do this with simplex?