1 files changed, 24 insertions, 0 deletions
diff --git a/lib/active_storage/verified_key_with_expiration.rb b/lib/active_storage/verified_key_with_expiration.rb
new file mode 100644
index 0000000000..8708106735
--- /dev/null
+++ b/lib/active_storage/verified_key_with_expiration.rb
@@ -0,0 +1,24 @@
+class ActiveStorage::VerifiedKeyWithExpiration
+  class_attribute :verifier, default: defined?(Rails) ? Rails.application.message_verifier('ActiveStorage') : nil
+
+  class << self
+    def encode(key, expires_in: nil)
+      verifier.generate([ key, expires_at(expires_in) ])
+    end
+
+    def decode(encoded_key)
+      key, expires_at = verifier.verified(encoded_key)
+
+      key if key && fresh?(expires_at)
+    end
+
+    private
+      def expires_at(expires_in)
+        expires_in ? Time.now.utc.advance(seconds: expires_in) : nil
+      end
+
+      def fresh?(expires_at)
+        expires_at.nil? || Time.now.utc < expires_at
+      end
+  end
+end