41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
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# ExtraChat
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ExtraChat is a Dalamud plugin and an associated server that function
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to add extra chat channels to FFXIV. Basically, this adds
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cross-data-centre linkshells that don't have a member limit.
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## Security and privacy
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For your privacy and to ensure a lack of liability for server hosts,
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messages and linkshell names are encrypted between the members of each
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linkshell. The server is unable to decrypt the content of messages or
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linkshell names.
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The server *does* know which characters are in which linkshells (an
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operational requirement).
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Due to this design decision, it is impossible for a server to moderate
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these extra linkshells, and linkshells will need to self-moderate
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instead. As such, there is no ability to report users.
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## Encryption details
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When a user initiates the process to create a linkshell, their client
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generates a random shared secret. The secret is saved locally by the
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client. When the user invites another user to the linkshell, a
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Diffie-Hellman key exchange is mediated by the server between the two
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users, and then the inviter transmits the shared secret to the
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invitee, encrypting it with their ephemeral shared secret created by
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the key exchange. Due to the nature of the Diffie-Hellman exchange,
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the server is unable to read the shared secret when it is sent.
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After this, the newly-invited user receives information about the
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linkshell they have been invited to, and can decrypt the name, as well
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as see any members. If the invitee decides to join, their client will
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save this shared secret.
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Any messages sent to the linkshell are encrypted with the shared
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secret, making their contents opaque to the server. The only way to
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read these messages is to know the shared secret, which the server is
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never able to discern.
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