loadkey.c

开发源代码的CPU卡的COS源程序。

/* ============================================================================
   Project Name : jayaCard
   Module Name  : proto/bios/crypto/loadkey.c
   Version : $Id: loadkey.c,v 1.10 2004/01/11 09:56:30 dgil Exp $

	Description: Crypto BIOS / Load Key

    The Original Code is jayaCard code.

    The Initial Developer of the Original Code is Gilles Dumortier.

	Portions created by the Initial Developer are Copyright (C) 2002-2004 the
    Initial Developer. All Rights Reserved.

    Contributor(s):

    This program 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.

    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.

    You should have received a copy of the GNU General Public License
    along with this program; see http://www.gnu.org/licenses/gpl.html

   History Rev	Description
   051103 dgil	wrote it from crypto.c
   ============================================================================
*/

#include "precomp.h"

/* =========================================================================
	__bios_loadkey(adr_in_eeprom,keylen)

	security:
		. check the following CRC
		. check loop invariant
		. check re-read equal first read
 		. increment the global semaphore

	in case of error, reset the cryptographic context.

	review __x XXX
		CRCing the key could be use to read some bits of the key from the
 		outside world if the CRC coprocessor not well protected :-(
   ========================================================================= */

void __bios_loadkey_from_eeprom(jword adr,jbyte keylen)
{
	LOCAL(jbyte,i);
	LOCAL(jbyte,crclo);
	LOCAL(jbyte,crchi);

	LOG2("KEY","__bios_loadkey_from_eeprom() adr=%.4X keylen=%d",adr,keylen);

	HAL_CRC_INIT();

	/* store also the CRC at the end of the register buffer so we can re-check
	   at key usage that the key is always valid !
		__x XXX implement check mechanism just before cryptoing with this key!
	*/
	crclo = 0x00;
	crchi = 0x00;
	keylen += 2;

	/* copy the key to the register area */
	i = JAYA_BCRYPTO_KEYCRC;
	while (keylen>0) {
		/* write the dest with the src */
		r.bBlock[i] = HAL_EEPROM_READ_BYTE(adr);

		/* then re-read to check the read is correct ! */
		if (r.bBlock[i]!=HAL_EEPROM_READ_BYTE(adr)) goto attack;
		adr++;

		/* CRC this byte */
		if (i==0) {
			crclo = r.bBlock[i];
		} else if (i==1) {
			crchi = r.bBlock[i];
		} else {
			HAL_CRC_COMPUTE(r.bBlock[i]);
		}
		i++;
		keylen--;
	}

	/* loop invariant checking */
	if (keylen>0) {
attack:
		/* under attack */
		BIOS_RESET_CONTEXT(ERR_FAULT);
		HAL_HALT();
		return;
	}
	gGlobalSem++;

	/* CRC checking */
	if ((HAL_CRC_LO()!=crclo) || (HAL_CRC_HI()!=crchi)) {
		LOG("BIOS","__bios_loadkey_from_eeprom(): invalid CRC !");
		BIOS_RESET_CONTEXT(ERR_INVALID_CRC);
	}
}

/* =========================================================================
	That's all folks !
   ========================================================================= */