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I'm not knowledgeable about this -- is signal's e2e encryption even viable for a service with N users, and one where new users are being added? Put another way

I'm not knowledgeable about this -- is signal's e2e encryption even viable for a service with N users, and one where new users are being added? Put another way, if I have a group with 10 users and it's encrypted and then another person joins and can see the old messages, was it actually securely encrypted in the first place?

AgentME 9y ago
I don't think Discord gives people access to past message history when joining a group. I don't know of any limitations of Signal's group chats that would be a problem for Discord's group chat behavior.
- sgtmas2006 9y ago
  It does give access to past messages.
  - Nuzzerino 9y ago
    It is one of the permission settings that can be toggled for a Discord chat room.
  - est 9y ago
    Discord support chat history sever side searches, they even posted a blog about how to optimise ElasticSsearch clusters. E2E encryption is useless here. Unless you setup some kind of dedicated channel for secretive group chats.
aeorgnoieang 9y ago
> if I have a group with 10 users and it's encrypted and then another person joins and can see the old messages, was it actually securely encrypted in the first place? Sure, why not? Assume, just because it's the first thing that came to mind, that message history is encrypted using GPG and every message is encrypted with everyone's individual public keys. When a new user joins, one user just encrypts the message history with the new user's public key. Or am I missing something? Do the existing users in the group not have access to their own message history?
- jarcoal 9y ago
  You’re not missing anything, this is definitely possible to do. That said, encrypting every message with everyone’s public key doesn’t scale, so instead you’d likely want to generate a symmetric key for the group and as new users are invited the inviter would encrypt the group key with the invitee’s public key. That makes it trivial for new users to view history, and as new chats are posted they only need to be encrypted with one key.

AgentME 9y ago

I don't think Discord gives people access to past message history when joining a group. I don't know of any limitations of Signal's group chats that would be a problem for Discord's group chat behavior.

sgtmas2006 9y ago
It does give access to past messages.
- Nuzzerino 9y ago
  It is one of the permission settings that can be toggled for a Discord chat room.
- est 9y ago
  Discord support chat history sever side searches, they even posted a blog about how to optimise ElasticSsearch clusters. E2E encryption is useless here. Unless you setup some kind of dedicated channel for secretive group chats.

aeorgnoieang 9y ago

> if I have a group with 10 users and it's encrypted and then another person joins and can see the old messages, was it actually securely encrypted in the first place? Sure, why not? Assume, just because it's the first thing that came to mind, that message history is encrypted using GPG and every message is encrypted with everyone's individual public keys. When a new user joins, one user just encrypts the message history with the new user's public key. Or am I missing something? Do the existing users in the group not have access to their own message history?

jarcoal 9y ago
You’re not missing anything, this is definitely possible to do. That said, encrypting every message with everyone’s public key doesn’t scale, so instead you’d likely want to generate a symmetric key for the group and as new users are invited the inviter would encrypt the group key with the invitee’s public key. That makes it trivial for new users to view history, and as new chats are posted they only need to be encrypted with one key.