🎉 Add keys namespace.

A modularized approach for key derivation.

backend/src/app/setup/keys.clj

@@ -0,0 +1,29 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) UXBOX Labs SL
+
+(ns app.setup.keys
+  "Keys derivation service."
+  (:require
+   [app.common.spec :as us]
+   [buddy.core.kdf :as bk]
+   [clojure.spec.alpha :as s]
+   [integrant.core :as ig]))
+
+(s/def ::secret-key ::us/string)
+(s/def ::props (s/keys :req-un [::secret-key]))
+
+(defmethod ig/pre-init-spec :app.setup/keys [_]
+  (s/keys :req-un [::props]))
+
+(defmethod ig/init-key :app.setup/keys
+  [_ {:keys [props] :as cfg}]
+  (fn [& {:keys [salt size]}]
+    (let [engine (bk/engine {:key (:secret-key props)
+                             :salt salt
+                             :alg :hkdf
+                             :digest :blake2b-512})]
+      (bk/get-bytes engine 32))))
+