Add support for signing ceritificate using a Secure element
Secure element communication is based on a mbed-os implementation that exposes a serial interface.
diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index 9cc582d..506d1e3 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -53,10 +53,12 @@
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/md.h"
#include "mbedtls/error.h"
+#include "mbedtls/pk_info.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <Windows.h>
#if defined(MBEDTLS_X509_CSR_PARSE_C)
#define USAGE_CSR \
@@ -90,6 +92,21 @@
#define DFL_CONSTRAINTS 1
#define DFL_DIGEST MBEDTLS_MD_SHA256
+typedef struct
+{
+ const char * serial_port;
+ unsigned char key_idx;
+}remote_serial_pk_context;
+
+int is_remote_key( const char * remote_info );
+int load_pubkey_from_remote( const char * remote_info, mbedtls_pk_context * ctx );
+int setup_opaque_privkey( const char * remote_info, mbedtls_pk_context * ctx );
+void mbedtls_pk_remote_free( mbedtls_pk_context * ctx );
+int serial_xfer( const char * serial_port, const unsigned char * tx_buf,
+ size_t tx_buf_len, unsigned char * rx_buf, size_t rx_buf_len,
+ size_t * rx_len );
+#define UNUSED(x) ((void)(x))
+
#define USAGE \
"\n usage: cert_write param=<>...\n" \
"\n acceptable parameters:\n" \
@@ -577,14 +594,23 @@
mbedtls_printf( " . Loading the subject key ..." );
fflush( stdout );
- ret = mbedtls_pk_parse_keyfile( &loaded_subject_key, opt.subject_key,
- opt.subject_pwd );
- if( ret != 0 )
+ if ( is_remote_key( opt.subject_key ) )
{
- mbedtls_strerror( ret, buf, 1024 );
- mbedtls_printf( " failed\n ! mbedtls_pk_parse_keyfile "
- "returned -0x%04x - %s\n\n", -ret, buf );
- goto exit;
+ ret = load_pubkey_from_remote( opt.subject_key, &loaded_subject_key );
+ if ( ret != 0 )
+ goto exit;
+ }
+ else
+ {
+ ret = mbedtls_pk_parse_keyfile( &loaded_subject_key, opt.subject_key,
+ opt.subject_pwd );
+ if( ret != 0 )
+ {
+ mbedtls_strerror( ret, buf, 1024 );
+ mbedtls_printf( " failed\n ! mbedtls_pk_parse_keyfile "
+ "returned -0x%04x - %s\n\n", -ret, buf );
+ goto exit;
+ }
}
mbedtls_printf( " ok\n" );
@@ -593,8 +619,18 @@
mbedtls_printf( " . Loading the issuer key ..." );
fflush( stdout );
- ret = mbedtls_pk_parse_keyfile( &loaded_issuer_key, opt.issuer_key,
- opt.issuer_pwd );
+ if ( is_remote_key( opt.issuer_key ) )
+ {
+ ret = setup_opaque_privkey( opt.issuer_key, &loaded_issuer_key );
+ if ( ret != 0 )
+ goto exit;
+ }
+ else
+ {
+ ret = mbedtls_pk_parse_keyfile( &loaded_issuer_key, opt.issuer_key,
+ opt.issuer_pwd );
+ }
+
if( ret != 0 )
{
mbedtls_strerror( ret, buf, 1024 );
@@ -791,7 +827,10 @@
exit:
mbedtls_x509write_crt_free( &crt );
mbedtls_pk_free( &loaded_subject_key );
- mbedtls_pk_free( &loaded_issuer_key );
+ if ( is_remote_key( opt.issuer_key ) )
+ mbedtls_pk_remote_free( &loaded_issuer_key );
+ else
+ mbedtls_pk_free( &loaded_issuer_key );
mbedtls_mpi_free( &serial );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
@@ -803,6 +842,357 @@
return( ret );
}
+
+/** Below magic pattern is used with ATCAECC508A demo application (or similar)
+ * running on target to differentiate between user input and cert_write.exe.
+ */
+#define REMOTE_KEY_CMD_TAG "remote"
+#define REMOTE_KEY_MAGIC_PATTERN "rEmOtEkEy"
+#define REMOTE_KEY_ID_MIN 0
+#define REMOTE_KEY_ID_MAX 7
+#define REMOTE_KEY_SERIAL_BAUD CBR_9600
+
+#define REMOTE_KEY_FUNC_GET_PUBKEY 0xA
+#define REMOTE_KEY_FUNC_SIGN 0xB
+
+extern mbedtls_pk_info_t mbedtls_eckey_info;
+
+int is_remote_key( const char * remote_info )
+{
+ size_t tag_len = strlen( REMOTE_KEY_CMD_TAG );
+ printf ("is_remote_key %s\n", remote_info);
+ if ( strlen( remote_info ) > tag_len &&
+ strncmp( remote_info, REMOTE_KEY_CMD_TAG, tag_len ) == 0 )
+ return 1;
+ return 0;
+}
+
+/** Load a transparent public key context with public key from remote device
+ * over serial.
+ * This function sends:
+ * rEmOtEkEy<char encoded function code=GetPubKey><char encoded private key ID>
+ * Receives:
+ * <4 bytes length indicator in network order><concatenated public key>
+ */
+int load_pubkey_from_remote( const char * remote_info, mbedtls_pk_context * ctx )
+{
+ int key_idx = 0, offset = 0, ret = 0;
+ const char * serial_port = NULL;
+ unsigned char func_buffer[10];
+ unsigned char pub_key_buf[100];
+ size_t rx_len = 0;
+ static mbedtls_ecp_keypair ecp_key;
+
+ offset = strlen( REMOTE_KEY_CMD_TAG );
+ key_idx = (int)remote_info[offset++];
+ key_idx = key_idx - 48; // ascii to decimal
+
+ if ( key_idx < REMOTE_KEY_ID_MIN || key_idx > REMOTE_KEY_ID_MAX )
+ {
+ mbedtls_printf( " failed\n ! Invalid remote key index %d\n\n", key_idx );
+ return( -1 );
+ }
+ serial_port = remote_info + offset;
+
+ /* Prepare command */
+ offset = 0;
+ func_buffer[offset++] = REMOTE_KEY_FUNC_GET_PUBKEY;
+ func_buffer[offset++] = key_idx;
+
+ if ( serial_xfer( serial_port, func_buffer, offset, pub_key_buf, sizeof( pub_key_buf ), &rx_len ) != 0 )
+ {
+ mbedtls_printf( " failed\n ! Serial error trying to get pulic key\n\n" );
+ return( -1 );
+ }
+
+ /* Import public key from received binary */
+ mbedtls_ecp_keypair_init(&ecp_key);
+ ret = mbedtls_ecp_group_load(&ecp_key.grp, MBEDTLS_ECP_DP_SECP256R1);
+ if ( ret != 0 )
+ return( -1 );
+ ret = mbedtls_ecp_point_read_binary(&ecp_key.grp, &ecp_key.Q, pub_key_buf, rx_len );
+ if ( ret != 0 )
+ {
+ mbedtls_printf( " failed\n ! Failed to read ecp key from binary\n\n" );
+ return( -1 );
+ }
+ ctx->pk_info = &mbedtls_eckey_info;
+ ctx->pk_ctx = &ecp_key;
+ return( 0 );
+}
+
+/**
+ * @brief Tell if can do the operation given by type
+ *
+ * @param type Target type
+ *
+ * @return 0 if context can't do the operations,
+ * 1 otherwise.
+ */
+static int remote_can_do_func(const void *ctx, mbedtls_pk_type_t type)
+{
+ UNUSED(ctx);
+ /* At the moment on ECDSA is supported */
+ return (MBEDTLS_PK_ECDSA == type);
+}
+
+/**
+ * @brief Use STSAFE private key for signature.
+ *
+ * @param ctx ECDSA context
+ * @param md_alg Algorithm that was used to hash the message
+ * @param hash Message hash
+ * @param hash_len Length of hash
+ * @param sig Buffer that will hold the signature
+ * @param sig_len Length of the signature written
+ * @param f_rng RNG function
+ * @param p_rng RNG parameter
+ *
+ * @retval 0 if successful, or 1.
+ */
+static int remote_sign_func(void *ctx, mbedtls_md_type_t md_alg,
+ const unsigned char *hash, size_t hash_len,
+ unsigned char *sig, size_t *sig_len,
+ int (*f_rng)(void *, unsigned char *, size_t),
+ void *p_rng)
+{
+ remote_serial_pk_context * remote_ctx = (remote_serial_pk_context *)ctx;
+ unsigned char func_buffer[1024];
+ size_t offset = 0;
+
+ UNUSED( f_rng );
+ UNUSED( p_rng );
+
+ if ( md_alg != MBEDTLS_MD_SHA256 )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ func_buffer[offset++] = REMOTE_KEY_FUNC_SIGN;
+ func_buffer[offset++] = remote_ctx->key_idx;
+ func_buffer[offset++] = hash_len >> 24;
+ func_buffer[offset++] = hash_len >> 16;
+ func_buffer[offset++] = hash_len >> 8;
+ func_buffer[offset++] = hash_len & 0xff;
+
+ memcpy( func_buffer + offset, hash, hash_len );
+ offset += hash_len;
+
+ if ( serial_xfer( remote_ctx->serial_port, func_buffer, offset, sig, 100/* FIXME */, sig_len ) != 0 )
+ {
+ mbedtls_printf( " failed\n ! Serial error in signing\n\n" );
+ return( -1 );
+ }
+
+ return( 0 );
+}
+
+int mbedtls_pk_remote_setup( mbedtls_pk_context * ctx, const char * serial_port, unsigned char key_idx )
+{
+ // allocate remote serial context
+ static remote_serial_pk_context remote;
+ /* Opaque private key */
+ static const mbedtls_pk_info_t remote_pk_info =
+ {
+ /* MBEDTLS_PK_ECKEY, */
+ MBEDTLS_PK_OPAQUE,
+ "RemoteSerial",
+ NULL,
+ remote_can_do_func,
+ NULL,
+ NULL,
+ remote_sign_func,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ NULL
+ };
+
+
+ if ( ctx == NULL )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ remote.serial_port = serial_port;
+ remote.key_idx = key_idx;
+ ctx->pk_ctx = (void *)&remote;
+ ctx->pk_info = &remote_pk_info;
+
+ return( 0 );
+}
+
+void mbedtls_pk_remote_free( mbedtls_pk_context * ctx )
+{
+ /* Nothing to free since remote context is statically allocated.
+ * Within this app there is no need to scrub the memory.
+ */
+ UNUSED( ctx );
+}
+
+int setup_opaque_privkey( const char * remote_info, mbedtls_pk_context * ctx )
+{
+ int key_idx = 0, offset = 0, ret = 0;
+ const char * serial_port = NULL;
+
+ offset = strlen( REMOTE_KEY_CMD_TAG );
+ key_idx = (int)remote_info[offset++];
+ key_idx = key_idx - 48; // ascii to decimal
+
+ if ( key_idx < REMOTE_KEY_ID_MIN || key_idx > REMOTE_KEY_ID_MAX )
+ {
+ mbedtls_printf( " failed\n ! Invalid remote key index %d\n\n", key_idx );
+ return( -1 );
+ }
+ serial_port = remote_info + offset;
+ ret = mbedtls_pk_remote_setup( ctx, serial_port, key_idx );
+ if ( ret != 0 )
+ {
+ mbedtls_printf( " failed\n ! remote pk setup failure \n\n" );
+ return( -1 );
+ }
+
+ return( 0 );
+}
+
+int serial_xfer( const char * serial_port, const unsigned char * tx_buf,
+ size_t tx_buf_len, unsigned char * rx_buf, size_t rx_buf_len,
+ size_t * rx_len )
+{
+ char comm_name[20];
+ HANDLE hComm;
+ DCB dcbConfig;
+ COMMTIMEOUTS commTimeout;
+ DWORD xfer_len;
+ unsigned char len_buf[sizeof(size_t)];
+ int ret = -1;
+ size_t len = 0, sync_pattern_idx = 0;
+
+ do
+ {
+ sprintf( comm_name, "\\\\.\\%s", serial_port );
+
+ // Open port
+ hComm = CreateFile( comm_name, GENERIC_READ | GENERIC_WRITE, 0, 0,
+ OPEN_EXISTING, 0, 0 );
+ if ( hComm == INVALID_HANDLE_VALUE )
+ {
+ mbedtls_printf( " failed\n ! failed to open port %s %lu\n\n", serial_port, GetLastError() );
+ break;
+ }
+
+ if( GetCommState( hComm, &dcbConfig ) )
+ {
+ /*
+ dcbConfig.fBinary = TRUE;
+ dcbConfig.fParity = TRUE;
+ */
+
+ dcbConfig.BaudRate = REMOTE_KEY_SERIAL_BAUD;
+ dcbConfig.Parity = NOPARITY;
+ dcbConfig.ByteSize = 8;
+ dcbConfig.StopBits = ONESTOPBIT;
+ dcbConfig.fOutxCtsFlow = FALSE; // No CTS output flow control
+ dcbConfig.fOutxDsrFlow = FALSE; // No DSR output flow control
+ dcbConfig.fDtrControl = DTR_CONTROL_DISABLE; // DTR flow control type
+ dcbConfig.fDsrSensitivity = FALSE; // DSR sensitivity
+ dcbConfig.fTXContinueOnXoff = TRUE; // XOFF continues Tx
+ dcbConfig.fOutX = FALSE; // No XON/XOFF out flow control
+ dcbConfig.fInX = FALSE; // No XON/XOFF in flow control
+ dcbConfig.fErrorChar = FALSE; // Disable error replacement
+ dcbConfig.fNull = FALSE; // Disable null stripping
+ dcbConfig.fRtsControl = RTS_CONTROL_DISABLE; // RTS flow control
+ dcbConfig.fAbortOnError = FALSE; // Do not abort reads/writes on error
+ }
+ else
+ break;
+
+ if( !SetCommState( hComm, &dcbConfig ) )
+ break;
+
+ if( GetCommTimeouts( hComm, &commTimeout ) )
+ {
+ commTimeout.ReadIntervalTimeout = 1000;
+ commTimeout.ReadTotalTimeoutMultiplier = 10;
+ commTimeout.ReadTotalTimeoutConstant = 1000;
+ commTimeout.WriteTotalTimeoutConstant = 1000;
+ commTimeout.WriteTotalTimeoutMultiplier = 10;
+ }
+ else
+ break;
+
+ if( !SetCommTimeouts( hComm, &commTimeout ) )
+ break;
+
+
+ /* Sync with peer */
+ if( !WriteFile( hComm, REMOTE_KEY_MAGIC_PATTERN, strlen(REMOTE_KEY_MAGIC_PATTERN),
+ &xfer_len, NULL ) )
+ break;
+
+ while( sync_pattern_idx != strlen(REMOTE_KEY_MAGIC_PATTERN) )
+ {
+ char c;
+
+ if( !ReadFile( hComm, &c, sizeof(c), &xfer_len, NULL ) )
+ break;
+ if ( c == REMOTE_KEY_MAGIC_PATTERN[sync_pattern_idx] )
+ sync_pattern_idx++;
+ else
+ sync_pattern_idx = 0;
+ }
+
+ /* Exit if there was a read error */
+ if ( sync_pattern_idx != strlen(REMOTE_KEY_MAGIC_PATTERN) )
+ {
+ printf("Failedi to sync!");
+ break;
+ }
+
+ {
+ size_t i;
+ printf("Tx: ");
+ for (i = 0; i < tx_buf_len; i++)
+ printf ("0x%02x ", (tx_buf)[i]);
+ printf("\n");
+ }
+ if( !WriteFile( hComm, tx_buf, tx_buf_len,
+ &xfer_len, NULL ) )
+ break;
+
+ /* Read length indicator */
+ if( !ReadFile( hComm, len_buf, sizeof(len_buf), &xfer_len, NULL ) )
+ break;
+
+ *rx_len = ( len_buf[0] << 24 ) | ( len_buf[1] << 16 ) | ( len_buf[2] << 8 ) | len_buf[3];
+ if ( *rx_len > rx_buf_len )
+ return( -1 );
+ /* Read payload */
+ while( len < *rx_len )
+ {
+ if( !ReadFile( hComm, rx_buf + len, *rx_len - len, &xfer_len, NULL ) )
+ break;
+ len += xfer_len;
+ }
+ printf("Received LI 0x%02x 0x%02x 0x%02x 0x%02x \n", len_buf[0], len_buf[1], len_buf[2], len_buf[3]);
+ {
+ size_t i;
+ printf("Rx: ");
+ for (i = 0; i < *rx_len; i++)
+ printf ("0x%02x ", (rx_buf)[i]);
+ printf("\n");
+ }
+
+ ret = 0;
+ } while( 0 );
+
+ if( hComm != INVALID_HANDLE_VALUE )
+ {
+ CloseHandle( hComm );
+ hComm = INVALID_HANDLE_VALUE;
+ }
+
+ return( ret );
+}
+
#endif /* MBEDTLS_X509_CRT_WRITE_C && MBEDTLS_X509_CRT_PARSE_C &&
MBEDTLS_FS_IO && MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C &&
MBEDTLS_ERROR_C && MBEDTLS_PEM_WRITE_C */