/home/dko/projects/mobilec/trunk/src/security/xyssl-0.7/programs/pkey/rsa_verify.c

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/*
 *  RSA/SHA-1 signature verification program
 *
 *  Copyright (C) 2006-2007  Christophe Devine
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License, version 2.1 as published by the Free Software Foundation.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA  02110-1301  USA
 */

#ifndef _CRT_SECURE_NO_DEPRECATE
#define _CRT_SECURE_NO_DEPRECATE 1
#endif

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

#include "xyssl/rsa.h"
#include "xyssl/sha1.h"

int main( int argc, char *argv[] )
{
    FILE *f;
    int ret, i, c;
    rsa_context rsa;
    unsigned char hash[20];
    unsigned char buf[512];

    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" );
    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( ( ret = rsa_read_public( &rsa, f ) ) != 0 )
    {
        printf( " failed\n  ! rsa_read_public returned %08x\n\n", ret );
        goto exit;
    }

    fclose( f );

    /*
     * Extract the RSA signature from the text file
     */
    ret = 1;
    i = strlen( argv[1] );
    memcpy( argv[1] + i, "-sig.txt", 9 );

    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++] = c;

    fclose( f );

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

    /*
     * Compute the SHA-1 hash of the input file and compare
     * it with the hash decrypted from the RSA signature.
     */
    printf( "\n  . Verifying the RSA/SHA-1 signature" );
    fflush( stdout );

    if( ( ret = sha1_file( argv[1], hash ) ) != 0 )
    {
        printf( " failed\n  ! Could not open or read %s\n\n", argv[1] );
        goto exit;
    }

    if( ( ret = rsa_pkcs1_verify( &rsa, RSA_SHA1, hash, 20,
                                  buf, rsa.len ) ) != 0 )
    {
        printf( " failed\n  ! rsa_pkcs1_verify returned %08x\n\n", ret );
        goto exit;
    }

    printf( "\n  . OK (the decrypted SHA-1 hash matches)\n\n" );

    ret = 0;

exit:

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

    return( ret );
}

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