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/*
* The RSA public-key cryptosystem
*
* Copyright (C) 2006-2011, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* 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; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* RSA was designed by Ron Rivest, Adi Shamir and Len Adleman.
*
* http://theory.lcs.mit.edu/~rivest/rsapaper.pdf
* http://www.cacr.math.uwaterloo.ca/hac/about/chap8.pdf
*/
#include <rsa_config.h>
#include <string.h>
#if defined(POLARSSL_RSA_C)
#include <rsa.h>
#include <stdio.h>
/*
* Initialize an RSA context
*/
extern void mymallocreset();
void rsa_init( rsa_context *ctx,
int padding,
int hash_id )
{
memset( ctx, 0, sizeof( rsa_context ) );
ctx->padding = padding;
ctx->hash_id = hash_id;
mymallocreset();
}
/*
* Do an RSA public key operation
*/
int rsa_public( rsa_context *ctx,
const unsigned char *input,
unsigned char *output )
{
int ret;
size_t olen;
mpi T;
mpi_init( &T );
MPI_CHK( mpi_read_binary( &T, input, ctx->len ) );
if ( mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
{
mpi_free( &T );
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
}
olen = ctx->len;
MPI_CHK( mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) );
MPI_CHK( mpi_write_binary( &T, output, olen ) );
cleanup:
mpi_free( &T );
if ( ret != 0 )
return( POLARSSL_ERR_RSA_PUBLIC_FAILED + ret );
return( 0 );
}
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function
*/
int rsa_rsassa_pkcs1_v15_verify( rsa_context *ctx,
int mode,
int hash_id,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig )
{
int ret;
size_t len, siglen;
unsigned char *p, c;
unsigned char buf[POLARSSL_MPI_MAX_SIZE];
if ( ctx->padding != RSA_PKCS_V15 )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
siglen = ctx->len;
if ( siglen < 16 || siglen > sizeof( buf ) )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
#ifdef CONFIG_EMU_BUILD
ret = ( mode == RSA_PUBLIC )
? rsa_public( ctx, sig, buf )
: rsa_private( ctx, sig, buf );
#else
if (mode != RSA_PUBLIC)
return ( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
ret = rsa_public( ctx, sig, buf );
#endif /* CONFIG_EMU_BUILD */
if ( ret != 0 )
return( ret );
p = buf;
if ( *p++ != 0 || *p++ != RSA_SIGN )
return( POLARSSL_ERR_RSA_INVALID_PADDING );
while ( *p != 0 )
{
if ( p >= buf + siglen - 1 || *p != 0xFF )
return( POLARSSL_ERR_RSA_INVALID_PADDING );
p++;
}
p++;
len = siglen - ( p - buf );
if ( len == 33 && hash_id == SIG_RSA_SHA1 )
{
if ( memcmp( p, ASN1_HASH_SHA1_ALT, 13 ) == 0 &&
memcmp( p + 13, hash, 20 ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
if ( len == 34 )
{
c = p[13];
p[13] = 0;
if ( memcmp( p, ASN1_HASH_MDX, 18 ) != 0 )
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
if ( ( c == 2 && hash_id == SIG_RSA_MD2 ) ||
( c == 4 && hash_id == SIG_RSA_MD4 ) ||
( c == 5 && hash_id == SIG_RSA_MD5 ) )
{
if ( memcmp( p + 18, hash, 16 ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
}
if ( len == 35 && hash_id == SIG_RSA_SHA1 )
{
if ( memcmp( p, ASN1_HASH_SHA1, 15 ) == 0 &&
memcmp( p + 15, hash, 20 ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
if ( ( len == 19 + 28 && p[14] == 4 && hash_id == SIG_RSA_SHA224 ) ||
( len == 19 + 32 && p[14] == 1 && hash_id == SIG_RSA_SHA256 ) ||
( len == 19 + 48 && p[14] == 2 && hash_id == SIG_RSA_SHA384 ) ||
( len == 19 + 64 && p[14] == 3 && hash_id == SIG_RSA_SHA512 ) )
{
c = p[1] - 17;
p[1] = 17;
p[14] = 0;
if( p[18] == c &&
memcmp( p, ASN1_HASH_SHA2X, 18 ) == 0 &&
memcmp( p + 19, hash, c ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
if ( len == hashlen && hash_id == SIG_RSA_RAW )
{
if ( memcmp( p, hash, hashlen ) == 0 )
return( 0 );
else
return( POLARSSL_ERR_RSA_VERIFY_FAILED );
}
return( POLARSSL_ERR_RSA_INVALID_PADDING );
}
/*
* Do an RSA operation and check the message digest
*/
int rsa_pkcs1_verify( rsa_context *ctx,
int mode,
int hash_id,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig )
{
int ret;
switch ( ctx->padding )
{
case RSA_PKCS_V15:
ret = rsa_rsassa_pkcs1_v15_verify( ctx, mode, hash_id,
hashlen, hash, sig );
break;
default:
return( POLARSSL_ERR_RSA_INVALID_PADDING );
}
return ret;
}
/*
* Free the components of an RSA key
*/
void rsa_free( rsa_context *ctx )
{
mpi_free( &ctx->RQ ); mpi_free( &ctx->RP ); mpi_free( &ctx->RN );
mpi_free( &ctx->QP ); mpi_free( &ctx->DQ ); mpi_free( &ctx->DP );
mpi_free( &ctx->Q ); mpi_free( &ctx->P ); mpi_free( &ctx->D );
mpi_free( &ctx->E ); mpi_free( &ctx->N );
}
#endif
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