/*
 *  RSA/SHA-1 signature verification program
 *
 *  Based on XySSL: Copyright (C) 2006-2008  Christophe Devine
 *
 *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
 *
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    * Neither the names of PolarSSL or XySSL nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *  
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 *  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _CRT_SECURE_NO_DEPRECATE
#define _CRT_SECURE_NO_DEPRECATE 1
#endif

#include <string.h>
#include <stdio.h>

#include "polarssl/rsa.h"
#include "polarssl/sha1.h"
#include "polarssl/mvMemPool.h"

int main( int argc, char *argv[] )
{
    FILE *f;
    int ret, i, c;
    rsa_context rsa;
    unsigned char hash[64];
    unsigned char buf[1024];

    ret = 1;
    if( argc != 2 )
    {
        printf( "usage: rsa_verify <filename>\n" );

#ifdef WIN32
        printf( "\n" );
#endif

        goto exit;
    }

    printf( "\n  . Reading public key from rsa_pub.txt\n" );
    fflush( stdout );

    if( ( f = fopen( "rsa_pub.txt", "rb" ) ) == NULL )
    {
        printf( " failed\n  ! Could not open rsa_pub.txt\n" \
                "  ! Please run rsa_genkey first\n\n" );
        goto exit;
    }

	if (mpool_init() != 0) {
		printf( "mpool_init failed \n" );
		goto exit;
	}
	
    rsa_init( &rsa, RSA_PKCS_V15, 0, NULL, NULL );

    if( ( ret = mpi_read_file( &rsa.N, 16, f ) ) != 0 ||
        ( ret = mpi_read_file( &rsa.E, 16, f ) ) != 0 )
    {
        printf( " failed\n  ! mpi_read_file returned %d\n\n", ret );
        goto exit;
    }

    rsa.len = ( mpi_msb( &rsa.N ) + 7 ) >> 3;

    fclose( f );

    /*
     * Extract the RSA signature from the text file
     */
    ret = 1;
    i = strlen( argv[1] );
    memcpy( argv[1] + i, ".sig", 5 );

    if( ( f = fopen( argv[1], "rb" ) ) == NULL )
    {
        printf( "\n  ! Could not open %s\n\n", argv[1] );
        goto exit;
    }

    argv[1][i] = '\0', i = 0;

    while( fscanf( f, "%02X", &c ) > 0 &&
           i < (int) sizeof( buf ) )
        buf[i++] = (unsigned char) c;

    fclose( f );

    if( i != rsa.len )
    {
        printf( "\n  ! Invalid RSA signature format\n\n" );
        goto exit;
    }

    /*
     * Compute the SHA-512 hash of the input file and compare
     * it with the hash decrypted from the RSA signature.
     */
    printf( "\n  . Verifying the RSA/SHA-512 signature\n" );
    fflush( stdout );

    if( ( ret = sha4_file( argv[1], hash, 0 ) ) != 0 )
    {
        printf( " failed\n  ! Could not open or read %s\n\n", argv[1] );
        goto exit;
    }

    if( ( ret = rsa_pkcs1_verify( &rsa, RSA_PUBLIC, RSA_SHA512,
                                  64, hash, buf ) ) != 0 )
    {
        printf( " failed\n  ! rsa_pkcs1_verify returned %d\n\n", ret );
        goto exit;
    }

    printf( "\n  . OK (the decrypted SHA-512 hash matches)\n\n" );

    ret = 0;

exit:

#ifdef WIN32
    printf( "  + Press Enter to exit this program.\n" );
    fflush( stdout ); getchar();
#endif

    return( ret );
}