ARC4 support
diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst
index 7d3b072..4d0703b 100644
--- a/docs/hazmat/primitives/symmetric-encryption.rst
+++ b/docs/hazmat/primitives/symmetric-encryption.rst
@@ -149,6 +149,16 @@
:param bytes key: The secret key, 32-448 bits in length (in increments of
8). This must be kept secret.
+.. class:: ARC4(key)
+
+ ARC4 (Alleged RC4) is a stream cipher with serious weaknesses in its
+ initial stream output. Its use is strongly discouraged. ARC4 does not use
+ mode constructions.
+
+ :param bytes key: The secret key, ``40``, ``56``, ``64``, ``80``, ``128``,
+ ``192``, or ``256`` bits in length. This must be kept
+ secret.
+
Modes
~~~~~