.. _aes-ccm-functions:


AES-CCM Functions
=================


This section describes functions for authenticated encryption/decryption
using the Counter with Cipher Block Chaining-Message Authentication Code
(CCM) mode [`NIST SP
800-38C <bibliography.html>`__] of
the AES (Rijndael128) block cipher.


The AES-CCM functions enable authenticated encryption/decryption of
several messages using one key that the
`AES_CCMInit <aes_ccminit.html>`__
function sets. Processing of each new message starts with a call to the
`AES_CCMStart <aes_ccmstart.html>`__
function. The application code for conducting a typical AES-CCM
authenticated encryption should follow the sequence of operations as
outlined below:


#. Get the size required to configure the context IppsAES_CCMState by
   calling the function
   `AES_CCMGetSize <aes_ccmgetsize.html>`__.
#. Call the system memory-allocation service function to allocate a
   buffer whose size is not less than the function AES_CCMGetSize
   specifies.
#. Initialize the context IppsAES_CCMState\*pCtx by calling the function
   `AES_CCMInit <aes_ccminit.html>`__
   with the allocated buffer and respective AES key.
#. Optionally call
   `AES_CCMMessageLen <aes_ccmmessagelen.html>`__
   and/or
   `AES_CCMTagLen <aes_ccmtaglen.html>`__
   to set up message and tag parameters.
#. Call
   `AES_CCMStart <aes_ccmstart.html>`__
   to start authenticated encryption of the first/next message.
#. Keep calling
   `AES_CCMEncrypt <aes_ccmencrypt.html>`__
   until the entire message is processed.
#. Request the authentication tag by calling
   `AES_CCMGetTag <aes_ccmgettag.html>`__.
#. Proceed to the next message, if any, that is, go to step 5.
#. Clean up secret data stored in the context.
#. Call the system memory free service function to release the buffer
   allocated for the context IppsAES_CCMState, if needed.
   
.. rubric:: Related Information

:ref:`data-security-considerations`

.. toctree::
   :maxdepth: 1

   
   aes_ccmgetsize
   aes_ccminit
   aes_ccmstart
   aes_ccmencrypt
   aes_ccmdecrypt
   aes_ccmgettag
   aes_ccmmessagelen
   aes_ccmtaglen