Meson Threat Modelling

[Mikerah]

We need a threat modelling document that outlines Meson's threat model and what kind of adversary it can handle and what kind of adversary it doesn't take into account. This should give users of Meson a much better idea of what to expect and whether it's in line with their own personal threat models.

[Mikerah]

Deliverable: Threat Modelling document outlining a reasonable threat model for the Meson, cryptocurrency mixnet.