static int rsa_decrypt_wrap( void *ctx,
const unsigned char *input, size_t ilen,
unsigned char *output, size_t *olen, size_t osize,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
if( ilen != ((mbedtls_rsa_context *) ctx)->len )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
return( mbedtls_rsa_pkcs1_decrypt( (mbedtls_rsa_context *) ctx, f_rng, p_rng,
MBEDTLS_RSA_PRIVATE, olen, input, output, osize ) );
}
int decipher_aes_credentials(const unsigned char *private_key,
const unsigned char *ciphertext,
unsigned char *aes_credentials)
{
rsa_context rsa;
init_rsa_context_with_private_key(&rsa, private_key);
#ifdef USE_MBEDTLS
size_t len = 128;
int ret = mbedtls_rsa_pkcs1_decrypt(&rsa, mbedtls_default_rng, nullptr, MBEDTLS_RSA_PRIVATE, &len, ciphertext,
aes_credentials, 40);
#else
# if PLATFORM_ID == 6 || PLATFORM_ID == 8
int32_t len = 128;
# else
int len = 128;
# endif
int ret = rsa_pkcs1_decrypt(&rsa, RSA_PRIVATE, &len, ciphertext,
aes_credentials, 40);
#endif
rsa_free(&rsa);
return ret;
}
int main( int argc, char *argv[] )
{
FILE *f;
int ret, c;
size_t i;
mbedtls_rsa_context rsa;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
unsigned char result[1024];
unsigned char buf[512];
const char *pers = "rsa_decrypt";
((void) argv);
memset(result, 0, sizeof( result ) );
mbedtls_ctr_drbg_init( &ctr_drbg );
ret = 1;
if( argc != 1 )
{
mbedtls_printf( "usage: rsa_decrypt\n" );
#if defined(_WIN32)
mbedtls_printf( "\n" );
#endif
goto exit;
}
mbedtls_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
mbedtls_entropy_init( &entropy );
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( "\n . Reading private key from rsa_priv.txt" );
fflush( stdout );
if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
{
mbedtls_printf( " failed\n ! Could not open rsa_priv.txt\n" \
" ! Please run rsa_genkey first\n\n" );
goto exit;
}
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
if( ( ret = mbedtls_mpi_read_file( &rsa.N , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.E , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.D , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.P , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.Q , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.DP, 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.DQ, 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &rsa.QP, 16, f ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n", ret );
goto exit;
}
rsa.len = ( mbedtls_mpi_bitlen( &rsa.N ) + 7 ) >> 3;
fclose( f );
/*
* Extract the RSA encrypted value from the text file
*/
ret = 1;
if( ( f = fopen( "result-enc.txt", "rb" ) ) == NULL )
{
mbedtls_printf( "\n ! Could not open %s\n\n", "result-enc.txt" );
goto exit;
}
i = 0;
while( fscanf( f, "%02X", &c ) > 0 &&
i < (int) sizeof( buf ) )
buf[i++] = (unsigned char) c;
fclose( f );
if( i != rsa.len )
{
mbedtls_printf( "\n ! Invalid RSA signature format\n\n" );
goto exit;
}
/*
* Decrypt the encrypted RSA data and print the result.
*/
mbedtls_printf( "\n . Decrypting the encrypted data" );
fflush( stdout );
if( ( ret = mbedtls_rsa_pkcs1_decrypt( &rsa, mbedtls_ctr_drbg_random, &ctr_drbg,
MBEDTLS_RSA_PRIVATE, &i, buf, result,
1024 ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_decrypt returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( "\n . OK\n\n" );
mbedtls_printf( "The decrypted result is: '%s'\n\n", result );
ret = 0;
exit:
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 );
}