From e6040c527a118778354dd5773fd1e35e16271409 Mon Sep 17 00:00:00 2001
From: Niklas Lindgren <niklas@musicglue.com>
Date: Fri, 17 May 2024 16:42:20 +0300
Subject: [PATCH 1/3] style: naming

---
 test/erebus_test.exs | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/test/erebus_test.exs b/test/erebus_test.exs
index 0a2fbb5..00e6e64 100644
--- a/test/erebus_test.exs
+++ b/test/erebus_test.exs
@@ -10,7 +10,7 @@ defmodule Erebus.Test do
     :ok
   end
 
-  defmodule EncryptedStuff do
+  defmodule EncryptedModel do
     use Ecto.Schema
     import Ecto.Changeset
     import Erebus.Schema
@@ -47,11 +47,11 @@ defmodule Erebus.Test do
   end
 
   test "encrypting and decrypting data with ecto" do
-    model = %EncryptedStuff{}
+    model = %EncryptedModel{}
 
     encrypted =
       model
-      |> EncryptedStuff.changeset(%{first: "hello", second: "there"})
+      |> EncryptedModel.changeset(%{first: "hello", second: "there"})
       |> Ecto.Changeset.apply_changes()
       # simulate reloading with virtual fields emptied
       |> Map.merge(%{first: nil, second: nil})
@@ -86,7 +86,7 @@ defmodule Erebus.Test do
 
     encrypted_2 =
       encrypted
-      |> EncryptedStuff.changeset(%{second: "thereX"})
+      |> EncryptedModel.changeset(%{second: "thereX"})
       |> Ecto.Changeset.apply_changes()
 
     assert hash_before != encrypted_2.first_encrypted
@@ -96,7 +96,7 @@ defmodule Erebus.Test do
 
     encrypted_3 =
       encrypted
-      |> EncryptedStuff.changeset(%{other: "somestring"})
+      |> EncryptedModel.changeset(%{other: "somestring"})
       |> Ecto.Changeset.apply_changes()
 
     assert hash_before == encrypted_3.first_encrypted
@@ -104,11 +104,11 @@ defmodule Erebus.Test do
   end
 
   test "encrypting and decrypting data with one field being null" do
-    model = %EncryptedStuff{}
+    model = %EncryptedModel{}
 
     encrypted =
       model
-      |> EncryptedStuff.changeset(%{first: "hello"})
+      |> EncryptedModel.changeset(%{first: "hello"})
       |> Ecto.Changeset.apply_changes()
       # simulate reloading with virtual fields emptied
       |> Map.merge(%{first: nil})
@@ -130,11 +130,11 @@ defmodule Erebus.Test do
   end
 
   test "forcing data reencryption" do
-    model = %EncryptedStuff{first: "hello"}
+    model = %EncryptedModel{first: "hello"}
 
     encrypted =
       model
-      |> EncryptedStuff.changeset(%{}, true)
+      |> EncryptedModel.changeset(%{}, true)
       |> Ecto.Changeset.apply_changes()
       # simulate reloading with virtual fields emptied
       |> Map.merge(%{first: nil})

From 11a671d34e99d8b29d5bf84fd73bfd24d49cc6b4 Mon Sep 17 00:00:00 2001
From: Niklas Lindgren <niklas@musicglue.com>
Date: Fri, 17 May 2024 16:53:22 +0300
Subject: [PATCH 2/3] style: coding style

---
 lib/erebus.ex | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/lib/erebus.ex b/lib/erebus.ex
index 93fa103..1f69079 100644
--- a/lib/erebus.ex
+++ b/lib/erebus.ex
@@ -96,12 +96,13 @@ defmodule Erebus do
   * options - providing backend and options for that backend
   """
   def decrypt(struct, fields_to_decrypt, opts \\ []) do
-    encrypted_dek = struct.dek |> Erebus.EncryptedData.cast_if_needed()
+    encrypted_dek = Erebus.EncryptedData.cast_if_needed(struct.dek)
 
     decrypted_dek = Erebus.SymmetricKeyStore.get_key(encrypted_dek, opts)
 
     decrypted_fields =
-      Enum.map(fields_to_decrypt, fn field ->
+      fields_to_decrypt
+      |> Enum.map(fn field ->
         stringified_field = Atom.to_string(field)
 
         encrypted_field = Map.get(struct, String.to_atom(stringified_field <> "_encrypted"))
@@ -181,13 +182,18 @@ defmodule Erebus do
         nil ->
           nil
 
-        field ->
+        field_name ->
           aead = :crypto.strong_rand_bytes(16)
           iv = :crypto.strong_rand_bytes(16)
 
-          stringified = Atom.to_string(field)
+          stringified = Atom.to_string(field_name)
 
-          data_to_encrypt = struct.changes |> Map.get(field) || Map.get(struct.data, field)
+          data_to_encrypt =
+            Map.get_lazy(
+              struct.changes,
+              field_name,
+              fn -> Map.get(struct.data, field_name) end
+            )
 
           if not is_nil(data_to_encrypt) do
             {ciphertext, ciphertag} =

From b68d3b5a36af4a0831213966d87974e89fc4c1b2 Mon Sep 17 00:00:00 2001
From: Niklas Lindgren <niklas@musicglue.com>
Date: Fri, 17 May 2024 16:54:32 +0300
Subject: [PATCH 3/3] feat: keep nil values on cloaked fields

they don't need to be encrypted (although maybe they still should be, as
keeping nil values plain is revealing), but by discarding nil value fields
it becomes impossible to set a cloaked field to nil
---
 lib/erebus.ex        |  1 -
 test/erebus_test.exs | 11 +++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/erebus.ex b/lib/erebus.ex
index 1f69079..35a2834 100644
--- a/lib/erebus.ex
+++ b/lib/erebus.ex
@@ -224,7 +224,6 @@ defmodule Erebus do
             ]
           end
       end)
-      |> Enum.filter(& &1)
       |> List.flatten()
       |> Enum.into(%{})
 
diff --git a/test/erebus_test.exs b/test/erebus_test.exs
index 00e6e64..5880b31 100644
--- a/test/erebus_test.exs
+++ b/test/erebus_test.exs
@@ -153,4 +153,15 @@ defmodule Erebus.Test do
 
     assert "hello" == decrypted_first.first
   end
+
+  test "setting a field to nil" do
+    model = %EncryptedModel{first: "beep", second: "boop"}
+
+    encrypted =
+      model
+      |> EncryptedModel.changeset(%{}, true)
+      |> Ecto.Changeset.apply_changes()
+
+    raise "test not implemented"
+  end
 end