Introduce helper function to determine whether suite uses server CRT
This commit introduces a static helper function
`mbedtls_ssl_ciphersuite_uses_srv_cert()`
which determines whether a ciphersuite may make use of server-side CRTs.
This function is in turn uses in `mbedtls_ssl_parse_certificate()` to
skip certificate parsing for ciphersuites which don't involve CRTs.
Note: Ciphersuites not using server-side CRTs don't allow client-side CRTs
either, so it is safe to guard `mbedtls_ssl_{parse/write}_certificate()`
this way.
Note: Previously, the code uses a positive check over the suites
- MBEDTLS_KEY_EXCHANGE_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECDHE_PSK
- MBEDTLS_KEY_EXCHANGE_ECJPAKE,
while now, it uses a negative check over `mbedtls_ssl_ciphersuite_uses_srv_cert()`,
which checks for the suites
- MBEDTLS_KEY_EXCHANGE_RSA
- MBEDTLS_KEY_EXCHANGE_RSA_PSK
- MBEDTLS_KEY_EXCHANGE_DHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_RSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_RSA
- MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA
- MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA
This is equivalent since, together, those are all ciphersuites.
Quoting ssl_ciphersuites.h:
```
typedef enum {
MBEDTLS_KEY_EXCHANGE_NONE = 0,
MBEDTLS_KEY_EXCHANGE_RSA,
MBEDTLS_KEY_EXCHANGE_DHE_RSA,
MBEDTLS_KEY_EXCHANGE_ECDHE_RSA,
MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA,
MBEDTLS_KEY_EXCHANGE_PSK,
MBEDTLS_KEY_EXCHANGE_DHE_PSK,
MBEDTLS_KEY_EXCHANGE_RSA_PSK,
MBEDTLS_KEY_EXCHANGE_ECDHE_PSK,
MBEDTLS_KEY_EXCHANGE_ECDH_RSA,
MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA,
MBEDTLS_KEY_EXCHANGE_ECJPAKE,
} mbedtls_key_exchange_type_t;
```
diff --git a/include/mbedtls/ssl_ciphersuites.h b/include/mbedtls/ssl_ciphersuites.h
index 71053e5..7126783 100644
--- a/include/mbedtls/ssl_ciphersuites.h
+++ b/include/mbedtls/ssl_ciphersuites.h
@@ -486,6 +486,24 @@
}
}
+static inline int mbedtls_ssl_ciphersuite_uses_srv_cert( const mbedtls_ssl_ciphersuite_t *info )
+{
+ switch( info->key_exchange )
+ {
+ case MBEDTLS_KEY_EXCHANGE_RSA:
+ case MBEDTLS_KEY_EXCHANGE_RSA_PSK:
+ case MBEDTLS_KEY_EXCHANGE_DHE_RSA:
+ case MBEDTLS_KEY_EXCHANGE_ECDH_RSA:
+ case MBEDTLS_KEY_EXCHANGE_ECDHE_RSA:
+ case MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA:
+ case MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA:
+ return( 1 );
+
+ default:
+ return( 0 );
+ }
+}
+
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__DHE_ENABLED)
static inline int mbedtls_ssl_ciphersuite_uses_dhe( const mbedtls_ssl_ciphersuite_t *info )
{
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 104ed22..cd8fffc 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -5979,10 +5979,7 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
- if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+ if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
ssl->state++;
@@ -5999,10 +5996,7 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
- if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+ if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
ssl->state++;
@@ -6025,10 +6019,7 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
- if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+ if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
ssl->state++;
@@ -6169,7 +6160,6 @@
size_t i, n;
uint8_t alert;
-
if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
@@ -6384,10 +6374,7 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
- if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
- ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+ if( !mbedtls_ssl_ciphersuite_uses_srv_cert( ciphersuite_info ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
goto exit;