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<book id="libkcapi" revision="@@LIBVERSION@@">
 <bookinfo>
  <title>Linux Kernel Crypto API User Space Interface Library</title>

  <edition>@@LIBVERSION@@</edition>

  <authorgroup>
   <author>
    <firstname>Stephan</firstname>
    <surname>Mueller</surname>
    <affiliation>
     <address>
      <email>smueller@chronox.de</email>
     </address>
    </affiliation>
   </author>
  </authorgroup>

  <copyright>
   <year>2014</year>
   <holder>Stephan Mueller</holder>
  </copyright>


  <legalnotice>
   <para>
     This documentation is free software; you can redistribute
     it and/or modify it under the terms of the GNU General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later
     version.
   </para>

   <para>
     This program is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied
     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     See the GNU General Public License for more details.
   </para>

   <para>
     You should have received a copy of the GNU General Public
     License along with this program; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     MA 02111-1307 USA
   </para>

   <para>
     For more details see the file COPYING in the source
     distribution of Linux.
   </para>
  </legalnotice>
 </bookinfo>

 <toc></toc>

 <chapter id="Intro">
  <title>libkcapi - Linux Kernel Crypto API User Space Interface Library</title>

  <para>This documentation applies to version @@LIBVERSION@@.</para>

  <para>
   The Linux kernel exports a network interface of type AF_ALG to allow user
   space to utilize the kernel crypto API.
  </para>

  <para>
   libkcapi uses this network interface and exports easy to use APIs so that
   a developer does not need to consider the low-level network interface
   handling.
  </para>

  <para>
   The library does not implement any cipher algorithms. All consumer requests
   are sent to the kernel for processing. Results from the kernel crypto API
   are returned to the consumer via the library API.
  </para>

  <para>
   The kernel interface and therefore this library can be used by unprivileged
   processes.
  </para>

  <sect1><title>Version Number Schema</title>
   <para>
    The version numbers for this library have the following schema:
    MAJOR.MINOR.PATCHLEVEL
   </para>

   <para>
    Changes in the major number implies API and ABI incompatible changes, or
    functional changes that require consumer to be updated (as long as this
    number is zero, the API is not considered stable and can change without a
    bump of the major version).
   </para>

   <para>
    Changes in the minor version are API compatible, but the ABI may change.
    Functional enhancements only are added. Thus, a consumer can be left
    unchanged if enhancements are not considered. The consumer only needs to
    be recompiled.
   </para>

   <para>
    Patchlevel changes are API / ABI compatible. No functional changes, no
    enhancements are made. This release is a bug fixe release only. The
    consumer can be left unchanged and does not need to be recompiled.
   </para>
  </sect1>

  <sect1><title>Purpose Of AF_ALG</title>
   <para>
    With the presence of numerous user space cryptographic libraries,
    one may ask why is there a need for the kernel to expose its kernel
    crypto API to user space. As there are system calls and potentially
    memory copies needed before a cipher can be invoked, it should be
    typically slower than user space shared libraries.
   </para>

   <para>
    There are several reasons for AF_ALG:
     <itemizedlist>
      <listitem>
       <para>
        The first and most important item is the access to hardware
        accelerators and hardware devices whose technical interface can
        only be accessed from the kernel mode / supervisor state of the
        processor. Such support cannot be used from user space except
        through AF_ALG.
       </para>
      </listitem>
      <listitem>
       <para>
        When using user space libraries, all key material and other
        cryptographic sensitive parameters remains in the calling
        application's memory even when the application supplied the
        information to the library. When using AF_ALG, the key material
        and other sensitive parameters are handed to the kernel. The
        calling application now can reliably erase that information
        from its memory and just use the cipher handle to perform
        the cryptographic operations. If the application is cracked
        an attacker cannot obtain the key material.
       </para>
      </listitem>
      <listitem>
       <para>
        On memory constrained systems like embedded systems, the additional
        memory footprint of a user space cryptographic library may
        be too much. As the kernel requires the kernel crypto API to be
        present, reusing existing code should reduce the memory footprint.
       </para>
      </listitem>
     </itemizedlist>
   </para>

  </sect1>
 </chapter>

 <chapter id="Usage"><title>Programming Guidelines</title>
  <para>
   A consumer has to use the kcapi.h header file to link with libkcapi. The
   linking has to be performed using -lkcapi.
  </para>

  <para>
   In case a consumer does not want a shared library, the libkcapi C file and
   header file can also just copied to the consumer code and compiled along
   with it.
  </para>

  <para>
   A general requirement must be observed: setting of keys must be performed
   before any operation. Re-setting of keys is only permissible once
   all data in flight (sent to the kernel but the kernel's result is not yet
   obtained) is processed, i.e. no data is in flight any more.
  </para>

  <sect1><title>Convenience Functions</title>
   <para>
    To support various use cases, the API provided with libkcapi is extensive.
    Though, some developers want to simply use a given cipher without any
    specific details. To accommodate such users, libkcapi provides convenience
    functions or convenience wrappers.
   </para>

   <para>
    The convenience functions provide exactly one function call to perform one
    complete cipher operation, such as an AES CBC encryption operation or a
    SHA-256 hashing. The caller only needs to provide the input and
    output buffers of his data. The entire intrinsic operation of libkcapi
    is hidden from the user.
   </para>

   <para>
    Convenience functions are provided for the different cipher types. They are
    clearly marked in the API specification below.
   </para>
  </sect1>

  <sect1><title>Synchronous Symmetric Cipher API</title>
   <para>
    Symmetric ciphers can be used in the following different ways:
     <itemizedlist>
      <listitem>
       <para>
        One-shot API: The one-shot API performs an encryption operation
        with one API call. With that API call, the caller provides the input
        data and immediately receives the output from the cipher operation.
       </para>
      </listitem>
      <listitem>
       <para>
        Stream API: With the stream API, the caller can implement independent
        calls to send data to the kernel and receive data from the kernel.
        Multiple send calls can be inter-mixed with multiple receive calls.
        If the kernel buffer is full, the caller of a subsequent send call will
        be put to sleep. Conversely, if the buffer is empty, a caller trying
        to read data resulting from a cipher operation will be put to sleep.
        Sleeping callers will be woken up by the kernel once buffer space
        becomes available or data becomes available, respectively. The detached
        nature of the sending/receiving operation allows the implementation of
        multi-threaded applications where one or more threads send data and one
        or more threads receive data. The threads must operate on the same
        cipher handle. However, access to that cipher handle does not need to
        be serialized when the stream API calls are invoked as the API calls
        only read the cipher handle.
       </para>
      </listitem>
     </itemizedlist>
   </para>
  </sect1>

  <sect1><title>Asynchronous Symmetric Cipher API</title>
   <para>
    In addition to the symmetric cipher API, an asynchronous API is offered
    with the kcapi_cipher_*_aio and kcapi_aead_*_aio API calls. The concept of
    that API is to perform parallel operations of multiple encryption or
    decryption data streams.
   </para>

   <para>
    To use the AIO API, the caller must use the KCAPI_INIT_AIO with the
    kcapi_cipher_init function call to set up all additional logistics for
    handing AIO. That means, users which are not interested in AIO will
    not suffer from the additional memory overhead including the time required
    to allocate that memory required for AIO.
   </para>

   <para>
    This implies that the asynchronous API handles the scatter-gather lists
    referenced by the IOVECs differently compared to the synchronous APIs.
    Whereas the synchronous API references different parts of plaintext or
    ciphertext that are processed with one cipher operation, the IOVECs of the
    asynchronous API references plaintext or ciphertext where each IOVEC
    is processed with an independent cipher operation. I.e. when using AES-CBC
    with the synchronous API and the scatter-gather lists, all input data is
    sent to one invocation of the AES-CBC cipher. Conversely, the asynchronous
    API invokes one individual AES-CBC operation for each individual IOVEC.
   </para>

   <para>
    The asynchronous API is designed to perform an in-place operation where
    the buffers for the input data are used to store the output data.
   </para>

   <para>
    The asynchronous API in libkcapi as well as the kernel has a higher
    overhead for setting the cipher operation up. That means that if the
    caller only uses a one IOVEC with one associated cipher operation, the
    asynchronous API is expected to be slower compared to the synchronous API.
    But already with two or three combined cipher operations, the AIO
    API should be faster than the synchronous API. You may test the difference
    in performance with the test/kcapi test application by using the options -f
    for measuring the time of cipher operations in nanoseconds, -d for the
    number of parallel invocations and -x 1 for a symmetric one-shot cipher
    invocation and -x 9 for an asymmetric cipher operation with the given input
    data.
   </para>

   <para>
    The kernel offers the AIO interface since kernel version 4.1 (symmetric
    ciphers) and 4.7 (AEAD ciphers). The libkcapi implements a transparent
    fallback to use the synchronous cipher API in case the AIO support is not
    present for the current kernel. This allows the calling users to be
    agnostic of the kernel support. Nonetheless, libkcapi with report the lack
    of AIO support if AIO is requested as the fallback implementation has a
    slight performance overhead.
   </para>
  </sect1>

  <sect1><title>AEAD Cipher API</title>
   <para>
    AEAD ciphers implement a very similar API approach as the symmetric ciphers:
     <itemizedlist>
      <listitem>
       <para>
        One-shot API: The one-shot API performs an encryption operation
        with one API call. With that API call, the caller provides the input
        data and immediately receives the output from the cipher operation.
       </para>
      </listitem>
      <listitem>
       <para>
        Stream API: With the stream API, the caller can implement independent
        calls to send data to the kernel and receive data from the kernel.
        However, unlike the symmetric cipher API, one AEAD cipher operation
        must be considered as one unit as the integrity value is calculated
        for one encryption or decryption operation. The caller can use multiple
        calls to provide the input data. The last chunk of data must be
        sent to the kernel with the API call marking the last submission.
        Then, the cipher operation can be triggered with the recvmsg invocation.
        It is possible to implement a multi-threaded application as the
        thread triggering the cipher operation is put to sleep until the last
        block is received. Once the last block is received, the caller waiting
        on the cipher operation is woken up to obtain the data.
       </para>
      </listitem>
     </itemizedlist>
   </para>

   <sect2><title>Aynchronous AEAD Cipher API</title>
    <para>
     Similarly to the symmetric cipher API, the AEAD API supports
     asynchronous operation as well. The same concept regarding the IOVECs
     applies as discussed for the asynchronous symmetric cipher API above.
    </para>
   </sect2>

   <sect2><title>AEAD Memory Structure</title>
    <para>
     When using the stream API for AEAD, the caller must observe a particular
     order of data components. It is permissible that for each of the following
     data components multiple send calls are used. But in total, all send calls
     must send the AEAD data in the requested sequence. That sequence has
     changed with kernel 4.9. The following sequence is applicable to kernel
     versions up to and including 4.8:
    </para>

    <orderedlist>
     <listitem>
      <para>Associated Authentication Data: The AAD must be provided as a first
      chunk.</para>
     </listitem>
     <listitem>
      <para>Plaintext / Ciphertext: Following the AAD, the entire plaintext
      or ciphertext is provided that shall be encrypted and integrity protected
      or decrypted and whose integrity shall be verified.</para>
     </listitem>
     <listitem>
      <para>Authentication Tag: Regardless of an encryption or decryption,
      the authentication tag memory must be provided.</para>
     </listitem>
    </orderedlist>

    <para>
     The caller must provide memory that is identical in size for the input and
     output data, even parts of the memory is unused. For example, for
     encryption, the AEAD cipher operation only needs the AAD and the plaintext.
     Nonetheless, the interface requires that the memory is big enough to
     hold the tag as well. This requirement particularly aids the in-place
     cipher operation.
    </para>

    <para>
     Starting with kernel 4.9, the interface changed slightly such that the
     authentication tag memory is only needed in the output buffer for
     encryption and in the input buffer for decryption.
    </para>

    <para>
     To allow the calling application to be agnostic about the differences
     in the kernel interface, the calling application is offered additional
     API calls which should be used as follows:
    </para>

    <orderedlist>
     <listitem>
      <para>Obtain the required input buffer length for the cryptographic
      operation using the calls kcapi_aead_inbuflen_enc or
      kcapi_aead_inbuflen_dec.</para>
     </listitem>
     <listitem>
      <para>Obtain the required output buffer length for the cryptographic
      operation using the APIs of kcapi_aead_outbuflen_enc or
      kcapi_aead_outbuflen_dec.</para>
     </listitem>

     <listitem>
      <para>For an in-place operation with a linear buffer, do the following
      (for an example, see test/kcapi-main.c:cavs_aead()):
       <orderedlist>
        <listitem>
         <para>allocate memory that is max(inbuflen, outbuflen),</para>
        </listitem>
        <listitem>
         <para>call to kcapi_aead_getdata_input and kcapi_aead_getdata_output
         with the allocated memory pointer to obtain the pointers into that
         allocated memory where the AAD, plaintext / ciphertext and tag is to be
         provided,</para>
        </listitem>
        <listitem>
         <para>fill these AAD, plaintext/ciphertext and tag pointers with the
         respective data if they are non-NULL -- note, a NULL pointer may
         be returned for the tag pointer,</para>
        </listitem>
        <listitem>
         <para>invoke the crypto operation with the pointer to the allocated
         buffer and inbuflen is supplied to the.</para>
        </listitem>
       </orderedlist>
      </para>
     </listitem>

     <listitem>
      <para>For for separate, potentially non-contiguous buffers, do the
      following (for an example, see test/kcapi-main.c:cavs_aead_stream()):
       <orderedlist>
        <listitem>
         <para>ensure that your total buffer size for input and output complies
         with the result from the buffer lengths supplied by the aforementioned
         API calls,</para>
        </listitem>
        <listitem>
         <para>call to kcapi_aead_getdata_input and kcapi_aead_getdata_output
         with NULL pointers for the memory buffers to obtain the lengths for the
         AEAD data components,</para>
        </listitem>
        <listitem>
         <para>initialize the IOVECs and/or invoke the stream API with the
         independent buffers with the AAD, plaintext/ciphertext and tag if the
         associated length values are non-zero.</para>
        </listitem>
       </orderedlist>
      </para>
     </listitem>

    </orderedlist>

    <para>
     If the caller chooses to not implement an in-place operation, the kernel
     will copy the AAD data into the output buffer, so that the destination
     buffer will hold the the ciphertext or plaintext, the AAD data and the
     authentication tag (encryption only). The memory structure of the
     destination buffer is identical to the source buffer. (This is currently
     not yet implemented for all ciphers and will be fixed in future
     kernel versions.)
    </para>
   </sect2>
  </sect1>

  <sect1><title>Message Digest API</title>
   <para>
    Again, like for the symmetric ciphers, the message digest API implements
    the one-shot and the stream use cases. In addition, convenience wrapper
    functions for SHA-1 through SHA-512 are provided where the caller only
    provides its input data and the return buffer for obtaining a message
    digest or keyed message digest.
   </para>
  </sect1>

  <sect1><title>Asymmetric Cipher API</title>
   <para>
    The asymmetric cipher API provides access to the raw asymmetric operations
    (i.e. modular exponentiation).
   </para>
  </sect1>

  <sect1><title>Zero Copy</title>
   <para>
    When using the one-shot API for symmetric ciphers, AEAD ciphers,
    as well as message digests, the library uses the zero copy interface to
    provide the input data to the kernel. That means, the kernel operates on
    the user space pages.
   </para>

   <para>
    To ensure the efficiency of this zero copy approach, the caller should
    use a page-aligned data buffer for the input data. Non-aligned buffers
    would work also, but the kernel would need to perform more page
    accesses, lowering the throughput. Such an aligned buffer can be created,
    for example, using the following call - the value 4096 should be the size
    of one page on the system:
   </para>

   <programlisting>
    unsigned char buf[4096] __attribute__((__aligned__(4096)));
   </programlisting>
   
   <programlisting>
    unsigned char *buf;
    posix_memalign((void *)&amp;buf, PAGE_SIZE, buflen);
   </programlisting>
  </sect1>

  <sect1><title>Memory Allocation</title>
   <para>
    The library libkcapi uses the data structure struct kcapi_handle as the
    cipher handle that allows the consumer to operate with the various function
    calls of this library.
   </para>

   <para>
    Unlike other crypto libraries, libkcapi does not allocate any memory or
    performs operations that implies memory allocation. struct kcapi_handle only
    holds pointers to the consumer-provided buffers with sensitive data. That
    means that the buffers holding sensitive data like keys are under full
    control of the consumer. Therefore, this library does not offer any memory
    allocation or secure memory clearing functions.
   </para>

   <para>
    The consumer must ensure that the memory is appropriately sanitized. The
    caller does not need to sanitize struct kcapi_handle as it does not contain
    any sensitive data.
   </para>
  </sect1>

  <sect1><title>Asynchronous I/O Use Cases and Libkcapi</title>
   <para>
    The kernel crypto API user space interface supports different use cases
    with the asynchronous I/O operations which are illustrated in the following
    sections. These sections also illustrate the API calls to be used to follow
    the respective use cases.
   </para>

   <para>
    All APIs that perform synchronous operation do not have different purposes
    and thus do not require special precautions when using them.
   </para>

   <para>
    The different use cases round asynchronous I/O revolve around different
    ways how to send data to the kernel and to retrieve processed data.
   </para>

   <sect2><title>Multiple Staged Cipher Operations</title>
    <para>
     Using the kcapi_cipher_*_aio and kcapi_aead_*_aio API calls, a caller can
     supply one or more IOVECs of data to the kernel. However, the caller can
     only supply one IV to the kernel.
    </para>

    <para>
     The API calls only allow specifying one integer defining the number of
     IOVECs in the arrays of the input data as well as the output data.
     The libkcapi library uses the input and output IOVECs as pairs. I.e.
     the first IOVEC of the input array relate to the first IOVEC of the output
     array, and so on.
    </para>

    <para>
     The kernel invokes the cipher operation when a recvmsg system call is
     processed. The AIO handling transforms each output IOVEC into one separate
     invocation of the recvmsg handler that processes the data submitted with
     the corresponding input IOVEC. This means, each output IOVEC will
     trigger one cipher operation. When multiple IOVECs are processed by the
     kernel's AIO handling, all resulting recvmsg calls are invoked with the
     in the data same order specified by the list of IOVECs.
    </para>

    <para>
     WARNING: Currently, it is not guaranteed that the drivers perform the proper
     serialization of the parallel processing of the different IOVECs. For
     example, when providing two IOVECs, they may be both using the initially
     set IV. Thus, they are not chained. User space is able to serialize
     the AIO operation in this case by invoking the AIO API calls with
     input/output IOVEC arrays holding one entry each only. However, this
     would imply that this type of invocation will not be different from a
     synchronous invocation.
    </para>
   </sect2>

   <sect2><title>Multiple Separate Cipher Operations</title>
    <para>
     The kernel and thus libkcapi supports the use case where several of the
     aforementioned multiple staged cipher operations are can be performed
     in parallel which are totally isolated from each other. In this case,
     different IVs are used.
    </para>

    <para>
     Using the kcapi_handle_reinit libkcapi API call, the caller can obtain
     a new cipher handle from an existing handle. Both share the same key
     and cipher -- the kernel crypto API maintains the same TFM data structure
     for both. However, both cipher handles can now encrypt or decrypt data
     completely isolated from each other. Specifically, the following data
     of a cipher operation is isolated between the different cipher handles --
     this is all data that is not set with a setsockopt(2) system call:

     <itemizedlist>
      <listitem>
       <para>Input: plaintext (encryption) or ciphertext (decryption)</para>
      </listitem>
      <listitem>
       <para>Output: plaintext (decryption) or ciphertext (encryption)</para>
      </listitem>
      <listitem>
       <para>IV</para>
      </listitem>
      <listitem>
       <para>AEAD: associated authenticated data (AAD) and its length</para>
      </listitem>
      <listitem>
       <para>AEAD: tag</para>
      </listitem>
     </itemizedlist>

     The following data is shared between the different cipher handles -- this
     covers all data that can be set with a setsockopt(2) system call:

     <itemizedlist>
      <listitem>
       <para>Key</para>
      </listitem>
      <listitem>
       <para>AEAD: Tag length</para>
      </listitem>
     </itemizedlist>

     This means that the "multiple staged cipher operations" discussed above
     can be performed with each cipher handle independently.
    </para>

    <para>
     The call kcapi_handle_reinit does not open another socket, but implies
     that only a new accept(2) system call is performed.
    </para>
   </sect2>
  </sect1>

  <sect1><title>Kernel Interfaces</title>
   <para>
    Depending on the version of your kernel, some of the kernel interfaces
    the library depends on are not available. When using the respective library
    API functions, an error is returned during initialization of the cipher
    handle. The following interfaces are available:
   </para>

   <itemizedlist>
    <listitem>
     <para>kcapi_md_* usable since kernel version 3.0</para></listitem>
    <listitem>
     <para>kcapi_cipher_* usable since kernel version 3.0</para>
    </listitem>
    <listitem>
     <para>
      kcapi_rng_* kernel interface integrated into kernel version 4.0
     </para>
    </listitem>
    <listitem>
     <para>
      kcapi_aead_* kernel interface added to cryptodev-2.6 tree and should be
      usable with kernel version 4.2.
     </para>
    </listitem>
    <listitem>
     <para>
      kcapi_akcipher_* kernel interface is discussed for inclusion to the
      cryptodev-2.6 kernel tree.
     </para>
    </listitem>
   </itemizedlist>

   <sect2><title>Kernel Configuration</title>
    <para>
     To use libkcapi, the following kernel options need to be enabled:
    </para>

    <itemizedlist>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER enables the NETLINK_CRYPTO interface to allow
       obtaining information about the loaded ciphers. When compiled as module
       in older kernels (pre 3.18) the resulting crypto_user kernel module must
       be loaded manually.
      </para>
     </listitem>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API enables the core functionality of the user space
       interface handler.
      </para>
     </listitem>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API_HASH enables the "hash" interface (i.e. allows
       the use of all message digest and keyed message digest ciphers).
      </para>
     </listitem>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API_SKCIPHER enables the "skcipher" interface
       to use symmetric cipher algorithms.
      </para>
     </listitem>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API_AEAD enables the "aead" interface to use AEAD
       cipher algorithms. This support is currently discussed on LKML and
       therefore not present in the mainline kernel.
      </para>
     </listitem>
     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API_RNG enables the "rng" interface to use the
       random number generators.
      </para>
     </listitem>

     <listitem>
      <para>
       CONFIG_CRYPTO_USER_API_AKCIPHER enables the "akcipher" interface to use
       the asymmetric ciphers. This support is currently discussed on LKML
       and therefore not present in the mainline kernel.
      </para>
     </listitem>
    </itemizedlist>

    <para>
     In addition, the following patch must be applied if a kernel less than
     3.19-rc1 or the cryptodev-2.6 kernel tree is used:
     https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=5d4a5e770d97d87082067886e7097c920b338da5
    </para>

    <para>
     In addition, the following patch must be applied if a kernel less than
     3.19-rc1 or the cryptodev-2.6 kernel tree is used:
     https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=af8e80731a94ff9de9508b01d9e5d931d538dc6b
    </para>

    <para>
     In addition, the following patch must be applied if a kernel less than
     3.19-rc1 or the cryptodev-2.6 kernel tree is used:
     https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=25fb8638e919bc7431a73f2fb4a9713818ae2c9d
    </para>
   </sect2>
  </sect1>

  <sect1><title>Example Code</title>
   <para>
    Example code covering all available API calls is provided with the test
    code in the test/ directory.
   </para>
  </sect1>
 </chapter>

 <chapter id="API"><title>Programming Interface</title>
  <sect1><title>Common API</title>
!Pkcapi.h Common API
!Fkcapi.h kcapi_set_verbosity
!Fkcapi.h kcapi_versionstring
!Fkcapi.h kcapi_version
!Fkcapi.h kcapi_pad_iv
!Fkcapi.h kcapi_memset_secure
!Fkcapi.h kcapi_handle_reinit
   </sect1>
   <sect1><title>Symmetric Cipher API - Generic</title>
    <para>
     These generic API for symmetric ciphers calls are to be used for both, the
     one-shot and the stream encryption/decryption operations.
    </para>
!Pkcapi.h Symmetric Cipher API
!Fkcapi.h kcapi_cipher_init
!Fkcapi.h kcapi_cipher_destroy
!Fkcapi.h kcapi_cipher_setkey
!Fkcapi.h kcapi_cipher_ivsize
!Fkcapi.h kcapi_cipher_blocksize
   </sect1>
   <sect1><title>Synchronous Symmetric Cipher API - One Shot</title>
!Fkcapi.h kcapi_cipher_encrypt
!Fkcapi.h kcapi_cipher_decrypt
   </sect1>
   <sect1><title>Symmetric Cipher API - Convenience</title>
!Fkcapi.h kcapi_cipher_enc_aes_cbc
!Fkcapi.h kcapi_cipher_dec_aes_cbc
!Fkcapi.h kcapi_cipher_enc_aes_ctr
!Fkcapi.h kcapi_cipher_dec_aes_ctr
   </sect1>
   <sect1><title>Asynchronous Symmetric Cipher API - One Shot</title>
!Fkcapi.h kcapi_cipher_encrypt_aio
!Fkcapi.h kcapi_cipher_decrypt_aio
   </sect1>
   <sect1><title>Synchronous Symmetric Cipher API - Stream</title>
    <para>The stream API requires that first the cipher operation type is
    set with the init call, followed by an arbitrary number and mix of the
    update and op calls.</para>
!Fkcapi.h kcapi_cipher_stream_init_enc
!Fkcapi.h kcapi_cipher_stream_init_dec
!Fkcapi.h kcapi_cipher_stream_update
!Fkcapi.h kcapi_cipher_stream_update_last
!Fkcapi.h kcapi_cipher_stream_op
   </sect1>
   <sect1><title>AEAD Cipher API - Generic</title>
    <para>
     These generic API for symmetric ciphers calls are to be used for both, the
     one-shot and the stream encryption/decryption operations.
    </para>
!Pkcapi.h AEAD Cipher API
!Fkcapi.h kcapi_aead_init
!Fkcapi.h kcapi_aead_destroy
!Fkcapi.h kcapi_aead_setkey
!Fkcapi.h kcapi_aead_setassoclen
!Fkcapi.h kcapi_aead_settaglen
!Fkcapi.h kcapi_aead_ivsize
!Fkcapi.h kcapi_aead_blocksize
!Fkcapi.h kcapi_aead_authsize
!Fkcapi.h kcapi_aead_inbuflen_enc
!Fkcapi.h kcapi_aead_inbuflen_dec
!Fkcapi.h kcapi_aead_outbuflen_enc
!Fkcapi.h kcapi_aead_outbuflen_dec
!Fkcapi.h kcapi_aead_ccm_nonce_to_iv
!Fkcapi.h kcapi_aead_getdata_input
!Fkcapi.h kcapi_aead_getdata_output
   </sect1>
   <sect1><title>Synchronous AEAD Cipher API - One Shot</title>
!Fkcapi.h kcapi_aead_encrypt
!Fkcapi.h kcapi_aead_decrypt
   </sect1>
   <sect1><title>Aynchronous AEAD Cipher API - One Shot</title>
!Fkcapi.h kcapi_aead_encrypt_aio
!Fkcapi.h kcapi_aead_decrypt_aio
   </sect1>
      <sect1><title>Synchronous AEAD Cipher API - Stream</title>
!Fkcapi.h kcapi_aead_stream_init_enc
!Fkcapi.h kcapi_aead_stream_init_dec
!Fkcapi.h kcapi_aead_stream_update
!Fkcapi.h kcapi_aead_stream_update_last
!Fkcapi.h kcapi_aead_stream_op
   </sect1>
   <sect1><title>Message Digest Cipher API - Generic</title>
!Pkcapi.h Message Digest Cipher API
!Fkcapi.h kcapi_md_init
!Fkcapi.h kcapi_md_destroy
!Fkcapi.h kcapi_md_setkey
!Fkcapi.h kcapi_md_digestsize
   </sect1>
   <sect1><title>Message Digest Cipher API - One Shot</title>
!Fkcapi.h kcapi_md_digest
   </sect1>
   <sect1><title>Message Digest Cipher API - Convenience</title>
!Fkcapi.h kcapi_md_sha1
!Fkcapi.h kcapi_md_sha224
!Fkcapi.h kcapi_md_sha256
!Fkcapi.h kcapi_md_sha384
!Fkcapi.h kcapi_md_sha512
!Fkcapi.h kcapi_md_hmac_sha1
!Fkcapi.h kcapi_md_hmac_sha224
!Fkcapi.h kcapi_md_hmac_sha256
!Fkcapi.h kcapi_md_hmac_sha384
!Fkcapi.h kcapi_md_hmac_sha512
   </sect1>
   <sect1><title>Message Digest Cipher API - Stream</title>
!Fkcapi.h kcapi_md_update
!Fkcapi.h kcapi_md_final
   </sect1>
   <sect1><title>Random Number API</title>
!Pkcapi.h Random Number API
!Fkcapi.h kcapi_rng_init
!Fkcapi.h kcapi_rng_destroy
!Fkcapi.h kcapi_rng_seed
!Fkcapi.h kcapi_rng_generate
!Fkcapi.h kcapi_rng_seedsize
   </sect1>
   <sect1><title>Random Number API - Convenience</title>
!Fkcapi.h kcapi_rng_get_bytes
   </sect1>
   <sect1><title>Asymmetric Cipher API - Generic</title>
!Pkcapi.h Asymmetric Cipher API
!Fkcapi.h kcapi_akcipher_init
!Fkcapi.h kcapi_akcipher_destroy
!Fkcapi.h kcapi_akcipher_setkey
!Fkcapi.h kcapi_akcipher_setpubkey
   </sect1>
   <sect1><title>Synchronous asymmetric Cipher API - One Shot</title>
!Fkcapi.h kcapi_akcipher_encrypt
!Fkcapi.h kcapi_akcipher_decrypt
!Fkcapi.h kcapi_akcipher_sign
!Fkcapi.h kcapi_akcipher_verify
   </sect1>
   <sect1><title>Aynchronous asymmetric Cipher API - One Shot</title>
!Fkcapi.h kcapi_akcipher_encrypt_aio
!Fkcapi.h kcapi_akcipher_decrypt_aio
!Fkcapi.h kcapi_akcipher_sign_aio
!Fkcapi.h kcapi_akcipher_verify_aio
   </sect1>
   <sect1><title>Asymmetric Cipher API - Stream</title>
!Fkcapi.h kcapi_akcipher_stream_init_enc
!Fkcapi.h kcapi_akcipher_stream_init_dec
!Fkcapi.h kcapi_akcipher_stream_init_sgn
!Fkcapi.h kcapi_akcipher_stream_init_vfy
!Fkcapi.h kcapi_akcipher_stream_update
!Fkcapi.h kcapi_akcipher_stream_op
   </sect1>
   <sect1><title>Key Protocol Primitives API - Generic</title>
!Fkcapi.h kcapi_kpp_init
!Fkcapi.h kcapi_kpp_destroy
!Fkcapi.h kcapi_kpp_dh_setparam_pkcs3
!Fkcapi.h kcapi_kpp_ecdh_setcurve
!Fkcapi.h kcapi_kpp_setkey
   </sect1>
   <sect1><title>Synchronous Key Protocol Primitives API - One Shot</title>
!Fkcapi.h kcapi_kpp_keygen
!Fkcapi.h kcapi_kpp_ssgen
   </sect1>
   <sect1><title>Asynchronous Key Protocol Primitives API - One Shot</title>
!Fkcapi.h kcapi_kpp_keygen_aio
!Fkcapi.h kcapi_kpp_ssgen_aio
   </sect1>
   <sect1><title>Key Derivation Functions</title>
!Pkcapi.h Key Derivation Functions
!Fkcapi.h kcapi_kdf_dpi
!Fkcapi.h kcapi_kdf_fb
!Fkcapi.h kcapi_kdf_ctr
!Fkcapi.h kcapi_pbkdf
!Fkcapi.h kcapi_pbkdf_iteration_count
!Fkcapi.h kcapi_hkdf
   </sect1>
 </chapter>
</book>
