4758.c

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/****************************************************************************
*                                                                           *
*                        IBM 4758 Randomness-Gathering Code                 *
*                        Copyright Peter Gutmann 1998-2002                  *
*                                                                           *
****************************************************************************/

/* This module is part of the cryptlib continuously seeded pseudorandom
   number generator.  For usage conditions, see random.c */

/* General includes */

#include <time.h>
#include "../crypt.h"

/* OS-specific includes */

#include "scc_int.h"

/* The size of the returned random data and the number of calls we make for
   a slow poll.  Since the 4758 uses a hardware RNG, it doesn't matter if we
   call it several times in succession */

#define SCC_RANDOM_SIZE     8       /* 64 bits */
#define SCC_NO_CALLS        4       /* 256 bits total */

void fastPoll( void )
    {
    MESSAGE_DATA msgData;
    BYTE buffer[ SCC_RANDOM_SIZE ];

    sccGetRandomNumber( buffer, RANDOM_RANDOM );
    setResourceData( &msgData, buffer, SCC_RANDOM_SIZE );
    krnlSendMessage( SYSTEM_OBJECT_HANDLE, IMESSAGE_SETATTRIBUTE_S,
                     &msgData, CRYPT_IATTRIBUTE_ENTROPY );
    zeroise( buffer, SCC_RANDOM_SIZE );
    }

void slowPoll( void )
    {
    MESSAGE_DATA msgData;
    BYTE buffer[ SCC_RANDOM_SIZE * SCC_NO_CALLS ];
    int quality = 100, i;

    for( i = 0; i < SCC_NO_CALLS; i++ )
        sccGetRandomNumber( buffer + ( i * SCC_RANDOM_SIZE ), RANDOM_RANDOM );

    /* Add the data to the randomness pool */
    setResourceData( &msgData, buffer, SCC_RANDOM_SIZE * SCC_NO_CALLS );
    krnlSendMessage( SYSTEM_OBJECT_HANDLE, IMESSAGE_SETATTRIBUTE_S,
                     &msgData, CRYPT_IATTRIBUTE_ENTROPY );
    zeroise( buffer, SCC_RANDOM_SIZE * SCC_NO_CALLS );
    krnlSendMessage( SYSTEM_OBJECT_HANDLE, IMESSAGE_SETATTRIBUTE,
                     &quality, CRYPT_IATTRIBUTE_ENTROPY_QUALITY );
    }