1 files changed, 55 insertions, 0 deletions
diff --git a/app/models/keyring.rb b/app/models/keyring.rb
new file mode 100644
index 0000000..66f7bfd
--- /dev/null
+++ b/app/models/keyring.rb
@@ -0,0 +1,55 @@
+#
+# Keyring
+#
+# A collection of cryptographic keys.
+#
+
+class Keyring
+  class Error < RuntimeError
+  end
+
+  class NotFound < Error
+    def initialize(type)
+      super "no such key: #{type}"
+    end
+  end
+
+  def initialize(storage)
+    @storage = storage
+  end
+
+  def create(type, value)
+    raise Error, "key already exists" if storage.keys[type].present?
+    storage.set_key type, {type: type, value: value, rev: new_rev}.to_json
+    storage.save
+  end
+
+  def update(type, rev:, value:)
+    check_rev type, rev
+    storage.set_key type, {type: type, value: value, rev: new_rev}.to_json
+    storage.save
+  end
+
+  def delete(type, rev:)
+    check_rev type, rev
+    storage.delete_key type
+    storage.save
+  end
+
+  def key_of_type(type)
+    JSON.parse(storage.keys[type]) if storage.keys[type]
+  end
+
+  protected
+  attr_reader :storage
+
+  def check_rev(type, rev)
+    old = key_of_type(type)
+    raise NotFound, type unless old
+    raise Error, "wrong revision: #{rev}" unless old['rev'] == rev
+  end
+
+  def new_rev
+    SecureRandom.urlsafe_base64(8)
+  end
+end