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
This commit is contained in:
Gilles Peskine 2018-02-22 19:41:16 +01:00 committed by GitHub
commit 765ca4dcb5
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23

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@ -53,10 +53,14 @@ int main( void )
#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 @@ int main( void )
#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 @@ struct options
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 @@ int main( int argc, char *argv[] )
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 @@ int main( int argc, char *argv[] )
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 @@ exit:
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 */