docs: add encryption operator

docs/user_guide/source/engines/engines.rst

@@ -25,3 +25,4 @@ Parameters are passed at:
 .. include:: dataman.rst
 .. include:: inline.rst
 .. include:: null.rst
+.. include:: plugin.rst

docs/user_guide/source/engines/plugin.rst

@@ -0,0 +1,5 @@
+*************
+Plugin Engine
+*************
+
+For details on using the Plugin Engine, see the :ref:`Plugins` documentation.

docs/user_guide/source/operators/encryption.rst

@@ -0,0 +1,20 @@
+**********
+Encryption
+**********
+
+The Encryption Operator uses the :ref:`Plugins` interface.
+This operator uses `libsodium <https://doc.libsodium.org/>`_ for encrypting and decrypting data.
+If ADIOS can find libsodium at configure time, this plugin will be built.
+
+This operator will generate a secret key and encrypts the data with the key and a nonce as described in the libsodium `secret key cryptography docs <https://doc.libsodium.org/secret-key_cryptography/secretbox>`_.
+The key is saved to the specified ``SecretKeyFile`` and will be used for decryption. The key should be kept confidential since it is used to both encrypt and decrypt the data.
+
+Parameters to use with the Encryption operator:
+
+============================== ===================== ===========================================================
+ **Key**                       **Value Format**       **Explanation**
+============================== ===================== ===========================================================
+ PluginName                     string                Required. Name to refer to plugin, e.g., ``MyOperator``
+ PluginLibrary                  string                Required. Name of shared library, ``EncryptionOperator``
+ SecretKeyFile                  string                Required. Path to secret key file
+============================== ===================== ===========================================================

docs/user_guide/source/operators/operators.rst

@@ -25,3 +25,5 @@ Parameters are passed at:
 2. :ref:`Runtime Configuration Files` in the :ref:`ADIOS` component.
 
 .. include:: ZFPCompressor.rst
+.. include:: plugin.rst
+.. include:: encryption.rst

docs/user_guide/source/operators/plugin.rst

@@ -0,0 +1,6 @@
+***************
+Plugin Operator
+***************
+
+For details on using the Plugin Operator, see the :ref:`Plugins` documentation.
+