tls13: add generate handshake keys

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 592ba12..7176dee 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -70,27 +70,6 @@
 #define MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN  \
     MBEDTLS_MD_MAX_SIZE
 
-typedef struct
-{
-    unsigned char binder_key                  [ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char client_early_traffic_secret [ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char early_exporter_master_secret[ MBEDTLS_MD_MAX_SIZE ];
-} mbedtls_ssl_tls1_3_early_secrets;
-
-typedef struct
-{
-    unsigned char client_handshake_traffic_secret[ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char server_handshake_traffic_secret[ MBEDTLS_MD_MAX_SIZE ];
-} mbedtls_ssl_tls1_3_handshake_secrets;
-
-typedef struct
-{
-    unsigned char client_application_traffic_secret_N[ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char server_application_traffic_secret_N[ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char exporter_master_secret             [ MBEDTLS_MD_MAX_SIZE ];
-    unsigned char resumption_master_secret           [ MBEDTLS_MD_MAX_SIZE ];
-} mbedtls_ssl_tls1_3_application_secrets;
-
 /* Maximum desired length for expanded key material generated
  * by HKDF-Expand-Label.
  *
@@ -556,4 +535,20 @@
  * \returns    A negative error code on failure.
  */
 int mbedtls_ssl_tls13_key_schedule_stage_early_data( mbedtls_ssl_context *ssl );
+
+/**
+ * \brief Compute TLS 1.3 handshake traffic keys.
+ *
+ * \param ssl  The SSL context to operate on. This must be in
+ *             key schedule stage \c Handshake, see
+ *             mbedtls_ssl_tls13_key_schedule_stage_handshake().
+ * \param traffic_keys The address at which to store the handshake traffic key
+ *                     keys. This must be writable but may be uninitialized.
+ *
+ * \returns    \c 0 on success.
+ * \returns    A negative error code on failure.
+ */
+int mbedtls_ssl_tls13_generate_handshake_keys( mbedtls_ssl_context *ssl,
+                                               mbedtls_ssl_key_set *traffic_keys );
+
 #endif /* MBEDTLS_SSL_TLS1_3_KEYS_H */