Salmon creation.

lib/pleroma/web/salmon/salmon.ex

@@ -57,7 +57,7 @@ defmodule Pleroma.Web.Salmon do
     end
   end
 
-  defp decode_key("RSA." <> magickey) do
+  def decode_key("RSA." <> magickey) do
     make_integer = fn(bin) ->
       list = :erlang.binary_to_list(bin)
       Enum.reduce(list, 0, fn (el, acc) -> (acc <<< 8) ||| el end)
@@ -70,4 +70,58 @@ defmodule Pleroma.Web.Salmon do
 
     {:RSAPublicKey, modulus, exponent}
   end
+
+  def encode_key({:RSAPublicKey, modulus, exponent}) do
+    modulus_enc = :binary.encode_unsigned(modulus) |> Base.url_encode64
+    exponent_enc = :binary.encode_unsigned(exponent) |> Base.url_encode64
+
+    "RSA.#{modulus_enc}.#{exponent_enc}"
+  end
+
+  def generate_rsa_pem do
+    port = Port.open({:spawn, "openssl genrsa"}, [:binary])
+    {:ok, pem} = receive do
+      {^port, {:data, pem}} -> {:ok, pem}
+    end
+    Port.close(port)
+    if Regex.match?(~r/RSA PRIVATE KEY/, pem) do
+      {:ok, pem}
+    else
+      :error
+    end
+  end
+
+  def keys_from_pem(pem) do
+    [private_key_code] = :public_key.pem_decode(pem)
+    private_key = :public_key.pem_entry_decode(private_key_code)
+    {:RSAPrivateKey, _, modulus, exponent, _, _, _, _, _, _, _} = private_key
+    public_key = {:RSAPublicKey, modulus, exponent}
+    {:ok, private_key, public_key}
+  end
+
+  def encode(private_key, doc) do
+    type = "application/atom+xml"
+    encoding = "base64url"
+    alg = "RSA-SHA256"
+
+    signed_text = [doc, type, encoding, alg]
+    |> Enum.map(&Base.url_encode64/1)
+    |> Enum.join(".")
+
+    signature = :public_key.sign(signed_text, :sha256, private_key) |> to_string |> Base.url_encode64
+    doc_base64= doc |> Base.url_encode64
+
+    # Don't need proper xml building, these strings are safe to leave unescaped
+    salmon = """
+    <?xml version="1.0" encoding="UTF-8"?>
+    <me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
+      <me:data type="application/atom+xml">#{doc_base64}</me:data>
+      <me:encoding>#{encoding}</me:encoding>
+      <me:alg>#{alg}</me:alg>
+      <me:sig>#{signature}</me:sig>
+    </me:env>
+    """
+
+    {:ok, salmon}
+  end
 end