1 files changed, 46 insertions, 0 deletions
diff --git a/shard/lib/identity.ex b/shard/lib/identity.ex
new file mode 100644
index 0000000..f1899df
--- /dev/null
+++ b/shard/lib/identity.ex
@@ -0,0 +1,46 @@
+defmodule Shard.Identity do
+  use Agent
+  require Salty.Sign.Ed25519, as: Sign
+  require Logger
+
+  def start_link(_) do
+    Agent.start_link(__MODULE__, :init, [], name: __MODULE__)
+  end
+
+  def init() do
+    Logger.info "Generating keypair..."
+    {pk, sk} = gen_keypair(Application.get_env(:shard, :peer_id_suffix))
+    nick_suffix = pk
+                  |> binary_part(0, 3)
+                  |> Base.encode16
+                  |> String.downcase
+    %{
+      keypair:  {pk, sk},
+      nickname: "Anon" <> nick_suffix,
+    }
+  end
+
+  defp gen_keypair(suffix, n \\ 0) do
+    {:ok, pk, sk} = Sign.keypair
+    if rem(n, 10000) == 0 do
+      Logger.info "#{n}... expected #{:math.pow(256, byte_size(suffix))}"
+    end
+    if :binary.longest_common_suffix([pk, suffix]) == byte_size(suffix) do
+      {pk, sk}
+    else
+      gen_keypair(suffix, n+1)
+    end
+  end
+
+  def get_keypair() do
+    Agent.get(__MODULE__, &(&1.keypair))
+  end
+
+  def get_nickname() do
+    Agent.get(__MODULE__, &(&1.nickname))
+  end
+
+  def set_nickname(newnick) do
+    Agent.update(__MODULE__, &(%{&1 | nickname: newnick}))
+  end
+end