// This file was extracted from the TCG Published

// Trusted Platform Module Library

// Part 4: Supporting Routines

// Family "2.0"

// Level 00 Revision 01.16

// October 30, 2014

//#define __TPM_RNG_FOR_DEBUG__

//

//

//          Introduction

//

//     This file contains the interface to the OpenSSL() random number functions.

//

//          Includes

//

#include "OsslCryptoEngine.h"

int         s_entropyFailure;

//

//

//          Functions

//

//          _cpri__RngStartup()

//

//     This function is called to initialize the random number generator. It collects entropy from the platform to

//     seed the OpenSSL() random number generator.

//

LIB_EXPORT BOOL

_cpri__RngStartup(void)

{

     UINT32           entropySize;

     BYTE             entropy[MAX_RNG_ENTROPY_SIZE];

     INT32            returnedSize = 0;

     // Initialize the entropy source

     s_entropyFailure = FALSE;

     _plat__GetEntropy(NULL, 0);

     // Collect entropy until we have enough

     for(entropySize = 0;

         entropySize < MAX_RNG_ENTROPY_SIZE && returnedSize >= 0;

         entropySize += returnedSize)

     {

         returnedSize = _plat__GetEntropy(&entropy[entropySize],

                                             MAX_RNG_ENTROPY_SIZE - entropySize);

     }

     // Got some entropy on the last call and did not get an error

     if(returnedSize > 0)

     {

         // Seed OpenSSL with entropy

         RAND_seed(entropy, entropySize);

     }

     else

     {

         s_entropyFailure = TRUE;

     }

     return s_entropyFailure == FALSE;

}

//

//

//          _cpri__DrbgGetPutState()

//

//     This function is used to set the state of the RNG (direction == PUT_STATE) or to recover the state of the

//     RNG (direction == GET_STATE).

//

//

//

//     NOTE:           This not currently supported on OpenSSL() version.

//

LIB_EXPORT CRYPT_RESULT

_cpri__DrbgGetPutState(

    GET_PUT              direction,

    int                  bufferSize,

    BYTE                *buffer

    )

{

    UNREFERENCED_PARAMETER(direction);

    UNREFERENCED_PARAMETER(bufferSize);

    UNREFERENCED_PARAMETER(buffer);

    return CRYPT_SUCCESS;                 // Function is not implemented

}

//

//

//          _cpri__StirRandom()

//

//     This function is called to add external entropy to the OpenSSL() random number generator.

//

LIB_EXPORT CRYPT_RESULT

_cpri__StirRandom(

    INT32                entropySize,

    BYTE                *entropy

    )

{

    if (entropySize >= 0)

    {

        RAND_add((const void *)entropy, (int) entropySize, 0.0);

    }

    return CRYPT_SUCCESS;

}

//

//

//          _cpri__GenerateRandom()

//

//     This function is called to get a string of random bytes from the OpenSSL() random number generator. The

//     return value is the number of bytes placed in the buffer. If the number of bytes returned is not equal to the

//     number of bytes requested (randomSize) it is indicative of a failure of the OpenSSL() random number

//     generator and is probably fatal.

//

LIB_EXPORT UINT16

_cpri__GenerateRandom(

    INT32                randomSize,

    BYTE                *buffer

    )

{

    //

    // We don't do negative sizes or ones that are too large

    if (randomSize < 0 || randomSize > UINT16_MAX)

        return 0;

    // RAND_bytes uses 1 for success and we use 0

    if(RAND_bytes(buffer, randomSize) == 1)

        return (UINT16)randomSize;

    else

        return 0;

}

//

//

//

//          _cpri__GenerateSeededRandom()

//

//     This funciton is used to generate a pseudo-random number from some seed values This funciton returns

//     the same result each time it is called with the same parameters

//

LIB_EXPORT UINT16

_cpri__GenerateSeededRandom(

   INT32               randomSize,      //   IN: the size of the request

   BYTE               *random,          //   OUT: receives the data

   TPM_ALG_ID          hashAlg,         //   IN: used by KDF version but not here

   TPM2B              *seed,            //   IN: the seed value

   const char         *label,           //   IN: a label string (optional)

   TPM2B              *partyU,          //   IN: other data (oprtional)

   TPM2B              *partyV           //   IN: still more (optional)

   )

{

   return (_cpri__KDFa(hashAlg, seed, label, partyU, partyV,

                       randomSize * 8, random, NULL, FALSE));

}