padlock_rng.c

A Brief Guide to User/Hacker of VIA Padlock SDK

/*
 * Copyright 1998-2004 VIA Technologies, Inc. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * VIA, AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "padlock.h"
#include "via_ace.h"
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>

////////////////////////////////////////////////////////////////
// VIA Padlock SDK RNG API
int padlock_rng_available()
{
	int result = 0;

	PUSHREG
	asm("movl $0xC0000000, %%eax\n"
	    "cpuid\n"
				
	    "cmpl $0xC0000001, %%eax\n"
	    "jnz  err_label\n" 
			
	    "cpuid\n"	
			
	    "andl $0x0C, %%edx\n" 
	    "jz  err_label \n" 
	     		
	    "movl %1, %0 \n"
	    		
"err_label:\n"
	     :"=m"(result)
	     :"i"(1));
	POPREG

	return result;
}

static RNG_RESULT padlock_rng(unsigned char *rand, int rand_len)
{
	while(rand_len)
	{
		asm("pushl %edi\n"
		    "pushl %edx\n"
		   );
		asm("movl %0, %%edi\n"
		    "movl $3, %%edx\n"
		    :
		    :"m"(rand)
			);
		XSTORERNG
		asm("movl %%edi, %0\n"
		    "andl $0x0000000F, %%eax\n"
		    "subl %%eax, %1\n" 
		    :"=m"(rand), "=m"(rand_len)
		    :
			);
		asm("popl %edx\n"
		    "popl %edi\n"
		   );
	}
	
	return RNG_SUCCEEDED;
}

RNG_RESULT 
padlock_rng_rand(unsigned char *rand,int rand_len)
{

	int processing_len = 0;
	int processed_len = 0;
	unsigned char *temp_buffer;
        unsigned char *buffer;
	RNG_RESULT ret= RNG_SUCCEEDED;	
	
	if(NULL == rand)
	{
		printf("Random number storage address null pointer error!\n");
		return RNG_FAILED;
	}

	if (0 == rand_len)
	{
		return RNG_SUCCEEDED;
	}

	// first 16 bytes because RNG hardware may change the value after allocated memory
	// boundary second 16 bytes because RNG hardware need the destination memory address
	// is 16 bytes aligned
	temp_buffer = (unsigned char *)malloc(MAX_CIPHER_BUFFER_SIZE+16+16);
	if(temp_buffer == NULL)
	{
		printf("Fail to malloc buffer for RNG!\n");
		return RNG_FAILED;
	}

	buffer = ALIGN16(temp_buffer);

	processing_len = rand_len > MAX_CIPHER_BUFFER_SIZE ? MAX_CIPHER_BUFFER_SIZE : rand_len;
		
	do{
			
		ret = padlock_rng(buffer,processing_len);
		if(ret != AES_SUCCEEDED)
		{
			break;
		}
		
		memcpy(rand + processed_len, buffer, processing_len);
			
		processed_len = processed_len + processing_len;
			
		if((rand_len - processed_len) < MAX_CIPHER_BUFFER_SIZE)
		{
			processing_len = rand_len - processed_len;
		}
		
	}while(processed_len < rand_len);

	free( temp_buffer);

	return ret;
}