/*
* Check a private RSA key
*/
int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
{
int ret;
mbedtls_mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2, DP, DQ, QP;
if( ( ret = mbedtls_rsa_check_pubkey( ctx ) ) != 0 )
return( ret );
if( !ctx->P.p || !ctx->Q.p || !ctx->D.p )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
mbedtls_mpi_init( &PQ ); mbedtls_mpi_init( &DE ); mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 );
mbedtls_mpi_init( &H ); mbedtls_mpi_init( &I ); mbedtls_mpi_init( &G ); mbedtls_mpi_init( &G2 );
mbedtls_mpi_init( &L1 ); mbedtls_mpi_init( &L2 ); mbedtls_mpi_init( &DP ); mbedtls_mpi_init( &DQ );
mbedtls_mpi_init( &QP );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &PQ, &ctx->P, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DE, &ctx->D, &ctx->E ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G2, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L1, &L2, &H, &G2 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &I, &DE, &L1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DP, &ctx->D, &P1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DQ, &ctx->D, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &QP, &ctx->Q, &ctx->P ) );
/*
* Check for a valid PKCS1v2 private key
*/
if( mbedtls_mpi_cmp_mpi( &PQ, &ctx->N ) != 0 ||
mbedtls_mpi_cmp_mpi( &DP, &ctx->DP ) != 0 ||
mbedtls_mpi_cmp_mpi( &DQ, &ctx->DQ ) != 0 ||
mbedtls_mpi_cmp_mpi( &QP, &ctx->QP ) != 0 ||
mbedtls_mpi_cmp_int( &L2, 0 ) != 0 ||
mbedtls_mpi_cmp_int( &I, 1 ) != 0 ||
mbedtls_mpi_cmp_int( &G, 1 ) != 0 )
{
ret = MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
}
cleanup:
mbedtls_mpi_free( &PQ ); mbedtls_mpi_free( &DE ); mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 );
mbedtls_mpi_free( &H ); mbedtls_mpi_free( &I ); mbedtls_mpi_free( &G ); mbedtls_mpi_free( &G2 );
mbedtls_mpi_free( &L1 ); mbedtls_mpi_free( &L2 ); mbedtls_mpi_free( &DP ); mbedtls_mpi_free( &DQ );
mbedtls_mpi_free( &QP );
if( ret == MBEDTLS_ERR_RSA_KEY_CHECK_FAILED )
return( ret );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED + ret );
return( 0 );
}
/*
* Verify sanity of parameter with regards to P
*
* Parameter should be: 2 <= public_param <= P - 2
*
* For more information on the attack, see:
* http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
* http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2005-2643
*/
static int dhm_check_range( const mbedtls_mpi *param, const mbedtls_mpi *P )
{
mbedtls_mpi L, U;
int ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
mbedtls_mpi_init( &L ); mbedtls_mpi_init( &U );
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &L, 2 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &U, P, 2 ) );
if( mbedtls_mpi_cmp_mpi( param, &L ) >= 0 &&
mbedtls_mpi_cmp_mpi( param, &U ) <= 0 )
{
ret = 0;
}
cleanup:
mbedtls_mpi_free( &L ); mbedtls_mpi_free( &U );
return( ret );
}
int main( void )
{
int ret;
mbedtls_mpi E, P, Q, N, H, D, X, Y, Z;
mbedtls_mpi_init( &E ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q ); mbedtls_mpi_init( &N );
mbedtls_mpi_init( &H ); mbedtls_mpi_init( &D ); mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y );
mbedtls_mpi_init( &Z );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &P, 10, "2789" ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &Q, 10, "3203" ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &E, 10, "257" ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &N, &P, &Q ) );
mbedtls_printf( "\n Public key:\n\n" );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " N = ", &N, 10, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " E = ", &E, 10, NULL ) );
mbedtls_printf( "\n Private key:\n\n" );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " P = ", &P, 10, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " Q = ", &Q, 10, NULL ) );
#if defined(MBEDTLS_GENPRIME)
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P, &P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q, &Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P, &Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &D, &E, &H ) );
mbedtls_mpi_write_file( " D = E^-1 mod (P-1)*(Q-1) = ",
&D, 10, NULL );
#else
mbedtls_printf("\nTest skipped (MBEDTLS_GENPRIME not defined).\n\n");
#endif
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &X, 10, "55555" ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &Y, &X, &E, &N, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &Z, &Y, &D, &N, NULL ) );
mbedtls_printf( "\n RSA operation:\n\n" );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " X (plaintext) = ", &X, 10, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " Y (ciphertext) = X^E mod N = ", &Y, 10, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( " Z (decrypted) = Y^D mod N = ", &Z, 10, NULL ) );
mbedtls_printf( "\n" );
cleanup:
mbedtls_mpi_free( &E ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q ); mbedtls_mpi_free( &N );
mbedtls_mpi_free( &H ); mbedtls_mpi_free( &D ); mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y );
mbedtls_mpi_free( &Z );
if( ret != 0 )
{
mbedtls_printf( "\nAn error occurred.\n" );
ret = 1;
}
#if defined(_WIN32)
mbedtls_printf( " Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
return( ret );
}
int main( int argc, char **argv )
{
int ret = 1;
mbedtls_mpi G, P, Q;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
const char *pers = "dh_genprime";
FILE *fout;
int nbits = DFL_BITS;
int i;
char *p, *q;
mbedtls_mpi_init( &G ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
mbedtls_ctr_drbg_init( &ctr_drbg );
mbedtls_entropy_init( &entropy );
if( argc == 0 )
{
usage:
mbedtls_printf( USAGE );
return( 1 );
}
for( i = 1; i < argc; i++ )
{
p = argv[i];
if( ( q = strchr( p, '=' ) ) == NULL )
goto usage;
*q++ = '\0';
if( strcmp( p, "bits" ) == 0 )
{
nbits = atoi( q );
if( nbits < 0 || nbits > MBEDTLS_MPI_MAX_BITS )
goto usage;
}
else
goto usage;
}
if( ( ret = mbedtls_mpi_read_string( &G, 10, GENERATOR ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_string returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ! Generating large primes may take minutes!\n" );
mbedtls_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n . Generating the modulus, please wait..." );
fflush( stdout );
/*
* This can take a long time...
*/
if( ( ret = mbedtls_mpi_gen_prime( &P, nbits, 1,
mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_gen_prime returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n . Verifying that Q = (P-1)/2 is prime..." );
fflush( stdout );
if( ( ret = mbedtls_mpi_sub_int( &Q, &P, 1 ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_sub_int returned %d\n\n", ret );
goto exit;
}
if( ( ret = mbedtls_mpi_div_int( &Q, NULL, &Q, 2 ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_div_int returned %d\n\n", ret );
goto exit;
}
if( ( ret = mbedtls_mpi_is_prime( &Q, mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_is_prime returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n . Exporting the value in dh_prime.txt..." );
fflush( stdout );
if( ( fout = fopen( "dh_prime.txt", "wb+" ) ) == NULL )
{
ret = 1;
mbedtls_printf( " failed\n ! Could not create dh_prime.txt\n\n" );
goto exit;
}
if( ( ret = mbedtls_mpi_write_file( "P = ", &P, 16, fout ) != 0 ) ||
( ret = mbedtls_mpi_write_file( "G = ", &G, 16, fout ) != 0 ) )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_write_file returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n\n" );
fclose( fout );
exit:
mbedtls_mpi_free( &G ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
#if defined(_WIN32)
mbedtls_printf( " Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
return( ret );
}
/*
* Generate an RSA keypair
*/
int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
unsigned int nbits, int exponent )
{
int ret;
mbedtls_mpi P1, Q1, H, G;
if( f_rng == NULL || nbits < 128 || exponent < 3 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 ); mbedtls_mpi_init( &H ); mbedtls_mpi_init( &G );
/*
* find primes P and Q with Q < P so that:
* GCD( E, (P-1)*(Q-1) ) == 1
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) );
do
{
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, ( nbits + 1 ) >> 1, 0,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, ( nbits + 1 ) >> 1, 0,
f_rng, p_rng ) );
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
mbedtls_mpi_swap( &ctx->P, &ctx->Q );
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
continue;
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
if( mbedtls_mpi_bitlen( &ctx->N ) != nbits )
continue;
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) );
}
while( mbedtls_mpi_cmp_int( &G, 1 ) != 0 );
/*
* D = E^-1 mod ((P-1)*(Q-1))
* DP = D mod (P - 1)
* DQ = D mod (Q - 1)
* QP = Q^-1 mod P
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D , &ctx->E, &H ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
ctx->len = ( mbedtls_mpi_bitlen( &ctx->N ) + 7 ) >> 3;
cleanup:
mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); mbedtls_mpi_free( &H ); mbedtls_mpi_free( &G );
if( ret != 0 )
{
mbedtls_rsa_free( ctx );
return( MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret );
}
return( 0 );
}
