Improve documentation
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 27b0fc2..c0ec042 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2788,16 +2788,24 @@
#if defined(MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED)
unsigned char *p = ssl->out_msg + 4;
+ size_t len;
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
unsigned char *dig_signed = p;
- size_t dig_signed_len = 0, len;
- ((void) dig_signed);
- ((void) dig_signed_len);
- ((void) len);
-#endif /* MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED) */
+ size_t dig_signed_len = 0;
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
+#endif /* MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );
- /* For key exchanges involving ECDH, extract DH parameters from certificate here. */
+ /*
+ *
+ * Part 1: Extract static ECDH parameters and abort
+ * if ServerKeyExchange not needed.
+ *
+ */
+
+ /* For suites involving ECDH, extract DH parameters
+ * from certificate at this point. */
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__ECDH_ENABLED)
if( mbedtls_ssl_ciphersuite_uses_ecdh( ciphersuite_info ) )
{
@@ -2862,7 +2870,7 @@
MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
/*
- * For DHE key exchanges, add the DH parameters here.
+ * - DHE key exchanges
*/
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__DHE_ENABLED)
if( mbedtls_ssl_ciphersuite_uses_dhe( ciphersuite_info ) )
@@ -2913,7 +2921,7 @@
#endif /* MBEDTLS_KEY_EXCHANGE__SOME__DHE_ENABLED */
/*
- * For ECDHE key exchanges, add the ECDH parameters here.
+ * - ECDHE key exchanges
*/
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__ECDHE_ENABLED)
if( mbedtls_ssl_ciphersuite_uses_ecdhe( ciphersuite_info ) )
@@ -2959,8 +2967,10 @@
return( ret );
}
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
dig_signed = p;
dig_signed_len = len;
+#endif
p += len;
n += len;
@@ -2970,8 +2980,10 @@
#endif /* MBEDTLS_KEY_EXCHANGE__SOME__ECDHE_ENABLED */
/*
- * For key exchanges involving the server signing the (EC)DH parameters,
- * compute and add the signature here.
+ *
+ * Part 3: For key exchanges involving the server signing the
+ * exchange parameters, compute and add the signature here.
+ *
*/
#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
if( mbedtls_ssl_ciphersuite_uses_server_signature( ciphersuite_info ) )
@@ -3012,22 +3024,23 @@
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_1)
- if( ciphersuite_info->key_exchange ==
- MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA )
+ if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA )
{
+ /* B: Default hash SHA1 */
md_alg = MBEDTLS_MD_SHA1;
}
else
#endif /* MBEDTLS_SSL_PROTO_SSL3 || MBEDTLS_SSL_PROTO_TLS1 || \
MBEDTLS_SSL_PROTO_TLS1_1 */
{
+ /* C: MD5 + SHA1 */
md_alg = MBEDTLS_MD_NONE;
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "pick hash algorithm %d for signing", md_alg ) );
/*
- * Compute the hash to be signed
+ * 3.2: Compute the hash to be signed
*/
#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_1)
@@ -3052,6 +3065,7 @@
* SHA(ClientHello.random + ServerHello.random
* + ServerParams);
*/
+
mbedtls_md5_starts( &mbedtls_md5 );
mbedtls_md5_update( &mbedtls_md5, ssl->handshake->randbytes, 64 );
mbedtls_md5_update( &mbedtls_md5, dig_signed, dig_signed_len );
@@ -3113,7 +3127,7 @@
(unsigned int) ( mbedtls_md_get_size( mbedtls_md_info_from_type( md_alg ) ) ) );
/*
- * Compute and add the signature
+ * 3.3: Compute and add the signature
*/
if( mbedtls_ssl_own_key( ssl ) == NULL )
{
@@ -3124,7 +3138,8 @@
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
{
- /* For TLS 1.2, we need to specify signature and hash algorithm
+ /*
+ * For TLS 1.2, we need to specify signature and hash algorithm
* explicitly through a prefix to the signature.
*
* struct {
@@ -3163,6 +3178,8 @@
}
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED */
+ /* Done with actual work; add header and send. */
+
ssl->out_msglen = 4 + n;
ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
ssl->out_msg[0] = MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE;
