Merge pull request #1360 from mazimkhan/cert-write-AndrzejKurek-opaque-keys-interfaces
Add support for using opaque keys in cert_write.c to sign a certificate
diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index 9cc582d..2dca1a1 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -53,10 +53,14 @@
#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>
+#if defined(_WIN32)
+#include <Windows.h>
+#endif
#if defined(MBEDTLS_X509_CSR_PARSE_C)
#define USAGE_CSR \
@@ -90,6 +94,8 @@
#define DFL_CONSTRAINTS 1
#define DFL_DIGEST MBEDTLS_MD_SHA256
+#define UNUSED(x) ((void)(x))
+
#define USAGE \
"\n usage: cert_write param=<>...\n" \
"\n acceptable parameters:\n" \
@@ -179,6 +185,448 @@
unsigned char ns_cert_type; /* NS cert type */
} opt;
+#if defined(_WIN32)
+/** Below are the constants used for remote Opaque key implementation.
+ */
+
+/* Remote cryptoprocessor sync pattern. Sent to sync with the device before
+ * sending commands. */
+#define REMOTE_KEY_MAGIC_PATTERN "rEmOtEkEy"
+#define REMOTE_KEY_CMD_TAG "//opaque_pk/ATCA"
+#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
+
+int is_remote_key( const char *remote_info )
+{
+ size_t tag_len = strlen( REMOTE_KEY_CMD_TAG );
+ if ( strlen( remote_info ) > tag_len &&
+ strncmp( remote_info, REMOTE_KEY_CMD_TAG, tag_len ) == 0 )
+ return( 1 );
+ return( 0 );
+}
+
+int parse_remote_info( const char *remote_info, int *key_idx, const char **serial_port )
+{
+ size_t offset = 0;
+ size_t remote_info_len = strlen( remote_info );
+
+ if( !is_remote_key( remote_info ) )
+ return( -1 );
+
+ offset = strlen( REMOTE_KEY_CMD_TAG );
+ offset++; // Skip the delimiter. FUTURE: Add validation.
+ if( offset >= remote_info_len )
+ return( -1 );
+ *key_idx = (int) remote_info[offset++];
+ offset++; // Skip the delimiter
+ if( offset >= remote_info_len )
+ return( -1 );
+ *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;
+ printf( "Got key id %d and com port %s\n", *key_idx, *serial_port );
+ return( 0 );
+}
+
+/**
+ * @brief Send a command to remote cryptoprocessor and receive response.
+ *
+ * It
+ * - first sends a sync pattern 'rEmOtEkEy' and waits for an echo to sync
+ * with the remote.
+ * - Then it sends the tx buf supplied by the caller.
+ * - It waits for a 4 byte length indicator. Value 0 means error.
+ * - Finally it reads no. of bytes specified in received Length indicator
+ * and fills received data in rx_buf and returns.
+ * Note: success is considered when a length indicator > 0 is received and
+ * data size == length indicator is successfully received.
+ *
+ *
+ * @param serial_port Serial port to send & recv data.
+ * @param tx_buf Command Tx buffer
+ * @param tx_buf_len Tx buffer length
+ * @param rx_buf Out response Rx buffer
+ * @param rx_buf_len Rx buffer length
+ * @param rx_len Received data length
+ *
+ * @retval 0 if success, or -1.
+ */
+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 c, comm_name[20]; /* \\\\.\\COMxy = 11 characters at least */
+ HANDLE h_comm;
+ DCB dcb_config;
+ COMMTIMEOUTS comm_timeout;
+ 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 );
+
+ h_comm = CreateFile( comm_name, GENERIC_READ | GENERIC_WRITE, 0, 0,
+ OPEN_EXISTING, 0, 0 );
+ if ( h_comm == INVALID_HANDLE_VALUE )
+ {
+ mbedtls_printf( " failed\n ! failed to open port %s %lu\n\n", serial_port, GetLastError() );
+ break;
+ }
+
+ if( GetCommState( h_comm, &dcb_config ) )
+ {
+ dcb_config.BaudRate = REMOTE_KEY_SERIAL_BAUD;
+ dcb_config.Parity = NOPARITY;
+ dcb_config.ByteSize = 8;
+ dcb_config.StopBits = ONESTOPBIT;
+ dcb_config.fOutxCtsFlow = FALSE; // No CTS output flow control
+ dcb_config.fOutxDsrFlow = FALSE; // No DSR output flow control
+ dcb_config.fDtrControl = DTR_CONTROL_DISABLE; // DTR flow control type
+ dcb_config.fDsrSensitivity = FALSE; // DSR sensitivity
+ dcb_config.fTXContinueOnXoff = TRUE; // XOFF continues Tx
+ dcb_config.fOutX = FALSE; // No XON/XOFF out flow control
+ dcb_config.fInX = FALSE; // No XON/XOFF in flow control
+ dcb_config.fErrorChar = FALSE; // Disable error replacement
+ dcb_config.fNull = FALSE; // Disable null stripping
+ dcb_config.fRtsControl = RTS_CONTROL_DISABLE; // RTS flow control
+ dcb_config.fAbortOnError = FALSE; // Do not abort reads/writes on error
+ }
+ else
+ {
+ mbedtls_printf( " failed\n ! GetCommState returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ if( !SetCommState( h_comm, &dcb_config ) )
+ {
+ mbedtls_printf( " failed\n ! SetCommState returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ if( GetCommTimeouts( h_comm, &comm_timeout ) )
+ {
+ comm_timeout.ReadIntervalTimeout = 1000;
+ comm_timeout.ReadTotalTimeoutMultiplier = 10;
+ comm_timeout.ReadTotalTimeoutConstant = 1000;
+ comm_timeout.WriteTotalTimeoutConstant = 1000;
+ comm_timeout.WriteTotalTimeoutMultiplier = 10;
+ }
+ else
+ {
+ mbedtls_printf( " failed\n ! GetCommTimeouts returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ if( !SetCommTimeouts( h_comm, &comm_timeout ) )
+ {
+ mbedtls_printf( " failed\n ! SetCommTimeouts returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+
+ /* Flush data on serial before sending sync pattern */
+ while( ReadFile( h_comm, &c, sizeof(c), &xfer_len, NULL ) && xfer_len != 0 );
+ /* Sync with peer */
+ if( !WriteFile( h_comm, REMOTE_KEY_MAGIC_PATTERN, (DWORD)strlen(REMOTE_KEY_MAGIC_PATTERN),
+ &xfer_len, NULL ) )
+ {
+ mbedtls_printf( " failed\n ! WriteFile returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ while( sync_pattern_idx != strlen(REMOTE_KEY_MAGIC_PATTERN) )
+ {
+ if( !ReadFile( h_comm, &c, sizeof(c), &xfer_len, NULL ) )
+ {
+ mbedtls_printf( " failed\n ! ReadFile returned error %lu\n\n", GetLastError() );
+ 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) )
+ {
+ mbedtls_printf("Failed to sync!\n");
+ break;
+ }
+
+ {
+ size_t i;
+ printf("Tx: ");
+ for (i = 0; i < tx_buf_len; i++)
+ printf ("0x%02x ", (tx_buf)[i]);
+ printf("\n");
+ }
+ if( !WriteFile( h_comm, tx_buf, (DWORD)tx_buf_len,
+ &xfer_len, NULL ) )
+ {
+ mbedtls_printf( " failed\n ! WriteFile returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ /* Read LI (length indicator) */
+ if( !ReadFile( h_comm, len_buf, sizeof(len_buf), &xfer_len, NULL ) ) /* Serial error */
+ {
+ mbedtls_printf( " failed\n ! ReadFile returned error %lu\n\n", GetLastError() );
+ break;
+ }
+
+ *rx_len = ( len_buf[0] << 24 ) | ( len_buf[1] << 16 ) | ( len_buf[2] << 8 ) | len_buf[3];
+ if ( *rx_len == 0 ) /* LI == 0 indicates remote error */
+ {
+ mbedtls_printf( " failed\n ! Received length indicator == 0\n\n" );
+ break;
+ }
+ if ( *rx_len > rx_buf_len ) /* Buffer too small */
+ {
+ mbedtls_printf( " failed\n ! Buffer too small to hold received data\n\n" );
+ break;
+ }
+ /* Read payload */
+ len = 0;
+ while( len < *rx_len )
+ {
+ if( !ReadFile( h_comm, rx_buf + len, (DWORD)(*rx_len - len), &xfer_len, NULL ) )
+ {
+ mbedtls_printf( " failed\n ! ReadFile returned error %lu\n\n", GetLastError() );
+ break;
+ }
+ len += xfer_len;
+ }
+ if( len < *rx_len ) /* Serial error */
+ {
+ mbedtls_printf( " failed\n ! ReadFile returned error %lu\n\n", GetLastError() );
+ break;
+ }
+ 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( h_comm != INVALID_HANDLE_VALUE )
+ {
+ CloseHandle( h_comm );
+ h_comm = INVALID_HANDLE_VALUE;
+ }
+
+ return( ret );
+}
+
+/** 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[2]; /* Op code: 1 + key Id: 1 */
+ unsigned char pub_key_buf[65]; /* ECDSA Pub key: 64 + EC octet string format tag: 1 */
+ size_t rx_len = 0;
+ static mbedtls_ecp_keypair ecp_key;
+
+ if( parse_remote_info( remote_info, &key_idx, &serial_port ) != 0 )
+ return( -1 );
+
+ /* 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 )
+ {
+ mbedtls_printf( " failed\n ! Failed to load ecp group\n\n" );
+ return( ret );
+ }
+ 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( ret );
+ }
+ mbedtls_pk_setup( ctx, mbedtls_pk_info_from_type( MBEDTLS_PK_ECKEY ) );
+ ctx->pk_ctx = &ecp_key;
+ return( 0 );
+}
+
+/**
+ * @brief Tell if the context can do the operation given by type
+ *
+ * @param ctx PK Context
+ * @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 only ECDSA is supported */
+ return (MBEDTLS_PK_ECDSA == type);
+}
+
+typedef struct
+{
+ const char *serial_port;
+ unsigned char key_idx;
+} remote_serial_pk_context;
+
+/**
+ * @brief Sign using remote cryptoprocessor accessed over serial.
+ *
+ * @param ctx ECDSA context
+ * @param md_alg Hash Algorithm that was used to hash the message.
+ * Only SHA256 is supported.
+ * @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;
+ /* Required buffer = func 1 byte + key Id 1 byte + hash len 4 bytes + hash */
+ unsigned char func_buffer[MBEDTLS_MD_MAX_SIZE + 4 + 1 + 1];
+ size_t offset = 0;
+
+ UNUSED( f_rng );
+ UNUSED( p_rng );
+
+ /* Currently this feature only supports Crypto chip ATCAECC508A that only
+ * supports SHA256. */
+ if( md_alg != MBEDTLS_MD_SHA256 )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ if( hash_len + 4 + 1 + 1 > sizeof( func_buffer ) )
+ {
+ return( MBEDTLS_ERR_PK_BUFFER_TOO_SMALL );
+ }
+
+ func_buffer[offset++] = REMOTE_KEY_FUNC_SIGN;
+ func_buffer[offset++] = remote_ctx->key_idx;
+ func_buffer[offset++] = (unsigned char)(hash_len >> 24);
+ func_buffer[offset++] = (unsigned char)(hash_len >> 16);
+ func_buffer[offset++] = (unsigned char)(hash_len >> 8);
+ func_buffer[offset++] = (unsigned char)(hash_len);
+
+ memcpy( func_buffer + offset, hash, hash_len );
+ offset += hash_len;
+
+ if( serial_xfer( remote_ctx->serial_port, func_buffer, offset, sig,
+ MBEDTLS_ECDSA_MAX_SIG_LEN(256), sig_len ) != 0 )
+ {
+ mbedtls_printf( " failed\n ! Serial error in signing\n\n" );
+ return( -1 );
+ }
+
+ return( 0 );
+}
+
+void remote_free( void *ctx )
+{
+ /* Nothing to free since remote context is statically allocated.
+ * Within this app there is no need to scrub the memory.
+ */
+ UNUSED( ctx );
+}
+
+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_OPAQUE_INFO_1(
+ "RemoteSerial",
+ NULL,
+ remote_can_do_func,
+ NULL,
+ NULL,
+ remote_sign_func,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ remote_free,
+ NULL
+ );
+
+
+ if ( ctx == NULL )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ remote.serial_port = serial_port;
+ remote.key_idx = key_idx;
+ mbedtls_pk_setup( ctx, &remote_pk_info );
+ ctx->pk_ctx = (void *)&remote;
+
+ return( 0 );
+}
+
+int setup_opaque_privkey( const char * remote_info, mbedtls_pk_context * ctx )
+{
+ int key_idx = 0, ret = 0;
+ const char * serial_port = NULL;
+
+ if( parse_remote_info( remote_info, &key_idx, &serial_port ) != 0 )
+ return( -1 );
+
+ ret = mbedtls_pk_remote_setup( ctx, serial_port, key_idx );
+ if( ret != 0 )
+ {
+ mbedtls_printf( " failed\n ! remote pk setup failure \n\n" );
+ return( ret );
+ }
+
+ return( 0 );
+}
+#endif /* _WIN32 */
+
int write_certificate( mbedtls_x509write_cert *crt, const char *output_file,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
@@ -577,14 +1025,25 @@
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 defined(_WIN32)
+ 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
+#endif
+ {
+ 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 +1052,20 @@
mbedtls_printf( " . Loading the issuer key ..." );
fflush( stdout );
- ret = mbedtls_pk_parse_keyfile( &loaded_issuer_key, opt.issuer_key,
- opt.issuer_pwd );
+#if defined(_WIN32)
+ if ( is_remote_key( opt.issuer_key ) )
+ {
+ ret = setup_opaque_privkey( opt.issuer_key, &loaded_issuer_key );
+ if ( ret != 0 )
+ goto exit;
+ }
+ else
+#endif
+ {
+ ret = mbedtls_pk_parse_keyfile( &loaded_issuer_key, opt.issuer_key,
+ opt.issuer_pwd );
+ }
+
if( ret != 0 )
{
mbedtls_strerror( ret, buf, 1024 );
@@ -803,6 +1274,7 @@
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 */