.. _rsaverify_pss:

RSAVerify_PSS
=============


Carries out the RSA-SSA signature verification scheme.


Syntax
------


IppStatus ippsRSAVerify_PSS(const Ipp8u\* pMsg, int msgLen, const
Ipp8u\* pSign, int\* pIsSignValid, const IppsRSAPublicKeyState\* pKey,
IppHashAlgId hashAlg, Ipp8u\* pBuffer);


IppStatus ippsRSAVerify_PSS_rmf(const Ipp8u\* pMsg, int msgLen, const
Ipp8u\* pSign, int\* pIsSignValid, const IppsRSAPublicKeyState\* pKey,
const IppsHashMethod\* pMethod, Ipp8u\* pBuffer);


Include Files
-------------


``ippcp.h``


Parameters
----------


.. list-table::
   :header-rows: 0

   * -     pMsg
     -  Pointer to the octet message that has been signed.
   * -     msgLen
     -  Length in octets of the \*pMsg message.
   * -     pSign
     -  Pointer to the octet signature string to be verified.
   * -     pIsSignValid
     -  Pointer to the verification result.
   * -     pKey
     -  Pointer to the properly initialized IppsRSAPublicKeyState context.
   * -     hashAlg
     -  Identifier of the hash algorithm. For details, see table :ref:`Supported Hash Algorithms <one-way-hash-primitives>`.
   * -     pMethod
     -  Pointer to the hash method. For details, see :ref:`HashMethod <hashmethod>` functions.
   * -     pBuffer
     -  Pointer to the scratch buffer of size not less than returned by the :ref:`RSA_GetBufferSizePublicKey <rsa_getbuffersizepublickey-privatekey>` function.




Description
-----------

.. note::


   ippsRSAVerify_PSS API is deprecated. Please refer to :ref:`Deprecated Functions <appendix-b-deprecated-functions>`
   section for the recommendations for transition.

The function carries out the RSASSA-PSS signature verification scheme
defined in :term:`PKCS 1.2.1 <[PKCS 1.2.1]>`.
RSAVerify_PSS verifies the signature generated by the
:ref:`RSASign_PSS <rsasign_pss>`
function called with the same hashAlg or pMethod parameter.


.. note::


   This function has a *reduced memory footprint* version. To learn
   more, see :ref:`Reduced Memory Footprint Functions <one-way-hash-primitives>`.


Return Values
-------------


.. list-table::
   :header-rows: 0

   * -     ippStsNoErr
     -     Indicates no error. Any other value indicates an error or warning.
   * -     ippStsNullPtrErr
     -     Indicates an error condition if any of the specified pointers is NULL.
   * -     ippStsContextMatchErr
     -     Indicates an error condition if the context parameter does not match the operation.
   * -     ippStsIncompleteContextErr
     -     Indicates an error condition if the public key is not set up.
   * -     ippStsNotSupportedModeErr
     -      Indicates an error condition if the hashAlg parameter does not match any value of IppHashAlgId listed in table :ref:`Supported Hash Algorithms <one-way-hash-primitives>`.


.. rubric:: Related Information

:ref:`rsa_setpublickey-privatekeytype1-type2`
