Peer indices should be unpredictable and unique per session

[cloudflare]

Peer indices should be unpredictable and unique per session

[vkrasnov]

I don't think there is a requirement for that in the wireguard specification. Unlinkability is not a property of wireguard

[Lekensteyn]

I can't find "unlinkability" in the WG whitepaper either. Based on the message interactions and IP/ports the protocol is already linkable, but this decision could make it worse by having another way in the protocol to link sessions.

My third "problem" was based on a misinterpretation, I overlooked the >> 8. So the top 24 bit is used for the peer ID, the last 8 bits are reserved for the "cyclic session index" (incremented via inc_index in handshake.rs). So actually the session IDs are kind of unique.

Being able to identify a peer based on the sender ID is undesirable though. The WG protocol has a weak form of identity hiding, including a peer identifier violates this property even more.

[vkrasnov]

I am not sure it qualifies as a bug thought