tls13: add key_schedule_stage_early_data
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 ca892b1..592ba12 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -531,4 +531,29 @@
mbedtls_ssl_key_set const *traffic_keys,
mbedtls_ssl_context *ssl );
+/*
+ * TLS 1.3 key schedule evolutions
+ *
+ * Early Data -> Handshake -> Application
+ *
+ * Small wrappers around mbedtls_ssl_tls1_3_evolve_secret().
+ */
+
+/**
+ * \brief Begin TLS 1.3 key schedule by calculating early secret
+ * from chosen PSK.
+ *
+ * The TLS 1.3 key schedule can be viewed as a simple state machine
+ * with states Initial -> Early -> Handshake -> Application, and
+ * this function represents the Initial -> Early transition.
+ *
+ * In the early stage, mbedtls_ssl_tls1_3_generate_early_data_keys()
+ * can be used to derive the 0-RTT traffic keys.
+ *
+ * \param ssl The SSL context to operate on.
+ *
+ * \returns \c 0 on success.
+ * \returns A negative error code on failure.
+ */
+int mbedtls_ssl_tls13_key_schedule_stage_early_data( mbedtls_ssl_context *ssl );
#endif /* MBEDTLS_SSL_TLS1_3_KEYS_H */