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SNOW 3G Crypto Poll Mode Driver
===============================

The SNOW 3G PMD (**librte_pmd_snow3g**) provides poll mode crypto driver
support for utilizing Intel Libsso library, which implements F8 and F9 functions
for SNOW 3G UEA2 cipher and UIA2 hash algorithms.

Features
--------

SNOW 3G PMD has support for:

Cipher algorithm:

* RTE_CRYPTO_CIPHER_SNOW3G_UEA2

Authentication algorithm:

* RTE_CRYPTO_AUTH_SNOW3G_UIA2

Limitations
-----------

* Chained mbufs are not supported.
* SNOW 3G (UIA2) supported only if hash offset field is byte-aligned.
* In-place bit-level operations for SNOW 3G (UEA2) are not supported
  (if length and/or offset of data to be ciphered is not byte-aligned).

Installation
------------

To build DPDK with the SNOW3G_PMD the user is required to download
the export controlled ``libsso_snow3g`` library, by requesting it from
`<https://networkbuilders.intel.com/network-technologies/dpdk>`_.
Once approval has been granted, the user needs to log in
`<https://networkbuilders.intel.com/dpdklogin>`_
and click on "Snow3G Bit Stream crypto library" link, to download the library.
After downloading the library, the user needs to unpack and compile it
on their system before building DPDK::

   make snow3G

**Note**: When encrypting with SNOW3G UEA2, by default the library
encrypts blocks of 4 bytes, regardless the number of bytes to
be encrypted provided (which leads to a possible buffer overflow).
To avoid this situation, it is necessary not to pass
3GPP_SAFE_BUFFERS as a compilation flag.
For this, in the Makefile of the library, make sure that this flag
is commented out.::

  #EXTRA_CFLAGS  += -D_3GPP_SAFE_BUFFERS


Initialization
--------------

In order to enable this virtual crypto PMD, user must:

* Export the environmental variable LIBSSO_SNOW3G_PATH with the path where
  the library was extracted (snow3g folder).

* Build the LIBSSO_SNOW3G library (explained in Installation section).

* Set CONFIG_RTE_LIBRTE_PMD_SNOW3G=y in config/common_base.

To use the PMD in an application, user must:

* Call rte_vdev_init("crypto_snow3g") within the application.

* Use --vdev="crypto_snow3g" in the EAL options, which will call rte_vdev_init() internally.

The following parameters (all optional) can be provided in the previous two calls:

* socket_id: Specify the socket where the memory for the device is going to be allocated
  (by default, socket_id will be the socket where the core that is creating the PMD is running on).

* max_nb_queue_pairs: Specify the maximum number of queue pairs in the device (8 by default).

* max_nb_sessions: Specify the maximum number of sessions that can be created (2048 by default).

Example:

.. code-block:: console

    ./l2fwd-crypto -l 1 -n 4 --vdev="crypto_snow3g,socket_id=0,max_nb_sessions=128" \
    -- -p 1 --cdev SW --chain CIPHER_ONLY --cipher_algo "snow3g-uea2"
