source: svn/trunk/newcon3bcm2_21bu/dta/src/bootloader/signature.c @ 2

/***************************************************************************
 *     Copyright (c) 2003-2010, Broadcom Corporation
 *     All Rights Reserved
 *     Confidential Property of Broadcom Corporation
 *
 *  THIS SOFTWARE MAY ONLY BE USED SUBJECT TO AN EXECUTED SOFTWARE LICENSE
 *  AGREEMENT  BETWEEN THE USER AND BROADCOM.  YOU HAVE NO RIGHT TO USE OR
 *  EXPLOIT THIS MATERIAL EXCEPT SUBJECT TO THE TERMS OF SUCH AN AGREEMENT.
 *
 * $brcm_Workfile: $
 * $brcm_Revision: $
 * $brcm_Date: $
 *
 * Module Description: Digital signature processing routines
 *
 * Revision History:
 *
 * $brcm_Log: $
 * 
 *
 ***************************************************************************/

#include "sha1/sha1o.h"

/* forward declarations */
void SHA1Compute_ram( uint8 * image_ptr, int len, uint32 * digest );
int rsa_decrypt (void *in, void *pubkey, unsigned long *decrypted_digest);
#if defined(RSA_BITS)
#define DIGEST_SIZE     (RSA_BITS/8)
#define SHA1_OFFSET     ((RSA_BITS/32) - 5)
#else
#define DIGEST_SIZE     0x80
#define SHA1_OFFSET     27
#endif

int signature_check(unsigned long in, unsigned long size, unsigned long signature, unsigned long public_key)
{
   unsigned long sha1_output[5]; /* 20 bytes */
   unsigned long decrypted_digest[DIGEST_SIZE/sizeof(unsigned long)];
   int i;

   SHA1Compute_ram((unsigned char *)in, size*8, sha1_output);

    /* RSA decrypt the signature */
   if (rsa_decrypt((unsigned long*)(signature), (unsigned long*)public_key, decrypted_digest))
   {
      /* Check SHA1 digest */
      for (i=0; (i<5); i++)
         if (decrypted_digest[SHA1_OFFSET+i] != sha1_output[i]) 
            return 1;

      return 0;
   }
      
   return 1;    
}