Merge pull request #4919 from yuhaoth/pr/add-tls13-server-hello-parser

TLS1.3:ServerHello:Add parse server hello function
diff --git a/library/ecdh.c b/library/ecdh.c
index b72bd1f..ddd4ef5 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -806,6 +806,60 @@
 #endif
 }
 
+static int ecdh_tls13_read_public_internal( mbedtls_ecdh_context_mbed *ctx,
+                                            const unsigned char *buf,
+                                            size_t buf_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    const unsigned char *p = buf;
+    size_t data_len;
+
+    if( buf_len < 3 )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+    data_len = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+
+    if( data_len < 1 || data_len != ( buf_len - 2 ) )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+    if( ( ret = mbedtls_ecp_point_read_binary( &ctx->grp,
+                                               &ctx->Qp, p, data_len ) ) != 0)
+    {
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Parse and import the client's TLS 1.3 public value
+ */
+int mbedtls_ecdh_tls13_read_public( mbedtls_ecdh_context *ctx,
+                                    const unsigned char *buf,
+                                    size_t buf_len )
+{
+    ECDH_VALIDATE_RET( ctx != NULL );
+    ECDH_VALIDATE_RET( buf != NULL );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_tls13_read_public_internal( ctx, buf, buf_len ) );
+#else
+    switch( ctx->var )
+    {
+#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
+        case MBEDTLS_ECDH_VARIANT_EVEREST:
+            return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_tls13_read_public_internal( &ctx->ctx.mbed_ecdh,
+                                                     buf, buf_len ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
+}
+
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 
 #endif /* MBEDTLS_ECDH_C */
diff --git a/library/ecdh_misc.h b/library/ecdh_misc.h
index d1342f8..d0f338a 100644
--- a/library/ecdh_misc.h
+++ b/library/ecdh_misc.h
@@ -36,13 +36,19 @@
                                    mbedtls_ecp_group_id grp_id );
 
 /*
- * TLS 1.3 version of mbedtls_ecdh_make_params in ecdh.h
+ * TLS 1.3 version of mbedtls_ecdh_make_params
  */
 int mbedtls_ecdh_tls13_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
-                                    unsigned char *buf, size_t blen,
+                                    unsigned char *buf, size_t buf_len,
                                     int ( *f_rng )( void *, unsigned char *, size_t ),
                                     void *p_rng );
 
+/*
+ * TLS 1.3 version of mbedtls_ecdh_read_public
+ */
+int mbedtls_ecdh_tls13_read_public( mbedtls_ecdh_context *ctx,
+                                    const unsigned char *buf,
+                                    size_t buf_len );
 
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 9041c51..66fb26c 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -307,9 +307,10 @@
       + ( MBEDTLS_SSL_CID_OUT_LEN_MAX ) )
 #endif
 
-#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
 #define MBEDTLS_TLS1_3_MD_MAX_SIZE         MBEDTLS_MD_MAX_SIZE
-#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
+#define MBEDTLS_CLIENT_HELLO_RANDOM_LEN 32
+#define MBEDTLS_SERVER_HELLO_RANDOM_LEN 32
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
 /**
@@ -508,6 +509,27 @@
 };
 typedef struct mbedtls_ssl_key_set mbedtls_ssl_key_set;
 
+typedef struct
+{
+    unsigned char binder_key                  [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char client_early_traffic_secret [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char early_exporter_master_secret[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+} mbedtls_ssl_tls1_3_early_secrets;
+
+typedef struct
+{
+    unsigned char client_handshake_traffic_secret[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char server_handshake_traffic_secret[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+} mbedtls_ssl_tls1_3_handshake_secrets;
+
+typedef struct
+{
+    unsigned char client_application_traffic_secret_N[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char server_application_traffic_secret_N[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char exporter_master_secret             [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+    unsigned char resumption_master_secret           [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
+} mbedtls_ssl_tls1_3_application_secrets;
+
 /*
  * This structure contains the parameters only needed during handshake.
  */
@@ -696,7 +718,9 @@
 
     size_t pmslen;                      /*!<  premaster length        */
 
-    unsigned char randbytes[64];        /*!<  random bytes            */
+    unsigned char randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN +
+                            MBEDTLS_SERVER_HELLO_RANDOM_LEN];
+                                        /*!<  random bytes            */
     unsigned char premaster[MBEDTLS_PREMASTER_SIZE];
                                         /*!<  premaster secret        */
 
@@ -715,6 +739,8 @@
         unsigned char handshake[MBEDTLS_TLS1_3_MD_MAX_SIZE];
         unsigned char app      [MBEDTLS_TLS1_3_MD_MAX_SIZE];
     } tls1_3_master_secrets;
+
+    mbedtls_ssl_tls1_3_handshake_secrets tls13_hs_secrets;
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 
 #if defined(MBEDTLS_SSL_SESSION_TICKETS)
@@ -859,7 +885,9 @@
     /* We need the Hello random bytes in order to re-derive keys from the
      * Master Secret and other session info,
      * see ssl_tls12_populate_transform() */
-    unsigned char randbytes[64]; /*!< ServerHello.random+ClientHello.random */
+    unsigned char randbytes[MBEDTLS_SERVER_HELLO_RANDOM_LEN +
+                            MBEDTLS_CLIENT_HELLO_RANDOM_LEN];
+                            /*!< ServerHello.random+ClientHello.random */
 #endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
 };
 
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 633bb8d..979db31 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -29,11 +29,11 @@
 
 #include "mbedtls/debug.h"
 #include "mbedtls/error.h"
+#include "mbedtls/platform.h"
 
 #include "ssl_misc.h"
 #include "ecdh_misc.h"
-
-#define CLIENT_HELLO_RANDOM_LEN 32
+#include "ssl_tls13_keys.h"
 
 /* Write extensions */
 
@@ -92,6 +92,26 @@
     return( 0 );
 }
 
+static int ssl_tls13_parse_supported_versions_ext( mbedtls_ssl_context *ssl,
+                                                   const unsigned char *buf,
+                                                   const unsigned char *end )
+{
+    ((void) ssl);
+
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, 2);
+    if( buf[0] != MBEDTLS_SSL_MAJOR_VERSION_3 ||
+        buf[1] != MBEDTLS_SSL_MINOR_VERSION_4 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "unexpected version" ) );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    return( 0 );
+}
+
 #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
 
 /*
@@ -452,6 +472,127 @@
     return( ret );
 }
 
+#if defined(MBEDTLS_ECDH_C)
+
+static int ssl_tls13_check_ecdh_params( const mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ecp_curve_info *curve_info;
+    mbedtls_ecp_group_id grp_id;
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    grp_id = ssl->handshake->ecdh_ctx.grp.id;
+#else
+    grp_id = ssl->handshake->ecdh_ctx.grp_id;
+#endif
+
+    curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id );
+    if( curve_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
+
+    if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 )
+        return( -1 );
+
+    MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                            MBEDTLS_DEBUG_ECDH_QP );
+
+    return( 0 );
+}
+
+static int ssl_tls13_read_public_ecdhe_share( mbedtls_ssl_context *ssl,
+                                              const unsigned char *buf,
+                                              size_t buf_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    ret = mbedtls_ecdh_tls13_read_public( &ssl->handshake->ecdh_ctx,
+                                          buf, buf_len );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_tls13_read_public" ), ret );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    if( ssl_tls13_check_ecdh_params( ssl ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "ssl_tls13_check_ecdh_params() failed!" ) );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_ECDH_C */
+
+/*
+ * ssl_tls13_parse_key_share_ext()
+ *      Parse key_share extension in Server Hello
+ *
+ * struct {
+ *        KeyShareEntry server_share;
+ * } KeyShareServerHello;
+ * struct {
+ *        NamedGroup group;
+ *        opaque key_exchange<1..2^16-1>;
+ * } KeyShareEntry;
+ */
+static int ssl_tls13_parse_key_share_ext( mbedtls_ssl_context *ssl,
+                                          const unsigned char *buf,
+                                          const unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    const unsigned char *p = buf;
+    uint16_t group, offered_group;
+
+    /* ...
+     * NamedGroup group; (2 bytes)
+     * ...
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
+    group = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+
+    /* Check that the chosen group matches the one we offered. */
+    offered_group = ssl->handshake->offered_group_id;
+    if( offered_group != group )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "Invalid server key share, our group %u, their group %u",
+              (unsigned) offered_group, (unsigned) group ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
+                                      MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+    }
+
+#if defined(MBEDTLS_ECDH_C)
+    if( mbedtls_ssl_tls13_named_group_is_ecdhe( group ) )
+    {
+        /* Complete ECDHE key agreement */
+        ret = ssl_tls13_read_public_ecdhe_share( ssl, p, end - p );
+        if( ret != 0 )
+            return( ret );
+    }
+    else
+#endif /* MBEDTLS_ECDH_C */
+    if( 0 /* other KEMs? */ )
+    {
+        /* Do something */
+    }
+    else
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_KEY_SHARE;
+    return( ret );
+}
+
 #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
 
 /* Write cipher_suites
@@ -565,11 +706,11 @@
     p += 2;
 
     /* Write the random bytes ( random ).*/
-    MBEDTLS_SSL_CHK_BUF_PTR( p, end, CLIENT_HELLO_RANDOM_LEN );
-    memcpy( p, ssl->handshake->randbytes, CLIENT_HELLO_RANDOM_LEN );
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
+    memcpy( p, ssl->handshake->randbytes, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
     MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes",
-                           p, CLIENT_HELLO_RANDOM_LEN );
-    p += CLIENT_HELLO_RANDOM_LEN;
+                           p, MBEDTLS_CLIENT_HELLO_RANDOM_LEN );
+    p += MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
 
     /*
      * Write legacy_session_id
@@ -690,7 +831,7 @@
 
     if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng,
                                   ssl->handshake->randbytes,
-                                  CLIENT_HELLO_RANDOM_LEN ) ) != 0 )
+                                  MBEDTLS_CLIENT_HELLO_RANDOM_LEN ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
         return( ret );
@@ -738,13 +879,519 @@
 }
 
 /*
+ * Functions for parsing and processing Server Hello
+ */
+/* Returns a negative value on failure, and otherwise
+ * - SSL_SERVER_HELLO_COORDINATE_HELLO or
+ * - SSL_SERVER_HELLO_COORDINATE_HRR
+ * to indicate which message is expected and to be parsed next. */
+#define SSL_SERVER_HELLO_COORDINATE_HELLO 0
+#define SSL_SERVER_HELLO_COORDINATE_HRR 1
+static int ssl_server_hello_is_hrr( mbedtls_ssl_context *ssl,
+                                    const unsigned char *buf,
+                                    const unsigned char *end )
+{
+    static const unsigned char magic_hrr_string[MBEDTLS_SERVER_HELLO_RANDOM_LEN] =
+        { 0xCF, 0x21, 0xAD, 0x74, 0xE5, 0x9A, 0x61, 0x11,
+          0xBE, 0x1D, 0x8C, 0x02, 0x1E, 0x65, 0xB8, 0x91,
+          0xC2, 0xA2, 0x11, 0x16, 0x7A, 0xBB, 0x8C, 0x5E,
+          0x07, 0x9E, 0x09, 0xE2, 0xC8, 0xA8, 0x33 ,0x9C };
+
+    /* Check whether this message is a HelloRetryRequest ( HRR ) message.
+     *
+     * Server Hello and HRR are only distinguished by Random set to the
+     * special value of the SHA-256 of "HelloRetryRequest".
+     *
+     * struct {
+     *    ProtocolVersion legacy_version = 0x0303;
+     *    Random random;
+     *    opaque legacy_session_id_echo<0..32>;
+     *    CipherSuite cipher_suite;
+     *    uint8 legacy_compression_method = 0;
+     *    Extension extensions<6..2^16-1>;
+     * } ServerHello;
+     *
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( buf, end, 2 + sizeof( magic_hrr_string ) );
+
+    if( memcmp( buf + 2, magic_hrr_string, sizeof( magic_hrr_string ) ) == 0 )
+    {
+        return( SSL_SERVER_HELLO_COORDINATE_HRR );
+    }
+
+    return( SSL_SERVER_HELLO_COORDINATE_HELLO );
+}
+
+/* Fetch and preprocess
+ * Returns a negative value on failure, and otherwise
+ * - SSL_SERVER_HELLO_COORDINATE_HELLO or
+ * - SSL_SERVER_HELLO_COORDINATE_HRR
+ */
+static int ssl_tls13_server_hello_coordinate( mbedtls_ssl_context *ssl,
+                                              unsigned char **buf,
+                                              size_t *buf_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_read_record( ssl, 0 ) );
+
+    if( ( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE ) ||
+        ( ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_HELLO ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "unexpected message" ) );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE,
+                                      MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    *buf = ssl->in_msg + 4;
+    *buf_len = ssl->in_hslen - 4;
+
+    ret = ssl_server_hello_is_hrr( ssl, *buf, *buf + *buf_len );
+    switch( ret )
+    {
+        case SSL_SERVER_HELLO_COORDINATE_HELLO:
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "received ServerHello message" ) );
+            break;
+        case SSL_SERVER_HELLO_COORDINATE_HRR:
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "received HelloRetryRequest message" ) );
+            break;
+    }
+
+cleanup:
+
+    return( ret );
+}
+
+static int ssl_tls13_check_server_hello_session_id_echo( mbedtls_ssl_context *ssl,
+                                                         const unsigned char **buf,
+                                                         const unsigned char *end )
+{
+    const unsigned char *p = *buf;
+    size_t legacy_session_id_echo_len;
+
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
+    legacy_session_id_echo_len = *p++ ;
+
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, legacy_session_id_echo_len );
+
+    /* legacy_session_id_echo */
+    if( ssl->session_negotiate->id_len != legacy_session_id_echo_len ||
+        memcmp( ssl->session_negotiate->id, p , legacy_session_id_echo_len ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_BUF( 3, "Expected Session ID",
+                               ssl->session_negotiate->id,
+                               ssl->session_negotiate->id_len );
+        MBEDTLS_SSL_DEBUG_BUF( 3, "Received Session ID", p,
+                               legacy_session_id_echo_len );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
+
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    p += legacy_session_id_echo_len;
+    *buf = p;
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "Session ID", ssl->session_negotiate->id,
+                            ssl->session_negotiate->id_len );
+    return( 0 );
+}
+
+static int ssl_tls13_cipher_suite_is_offered( mbedtls_ssl_context *ssl,
+                                              int cipher_suite )
+{
+    const int *ciphersuite_list = ssl->conf->ciphersuite_list;
+
+    /* Check whether we have offered this ciphersuite */
+    for ( size_t i = 0; ciphersuite_list[i] != 0; i++ )
+    {
+        if( ciphersuite_list[i] == cipher_suite )
+        {
+            return( 1 );
+        }
+    }
+    return( 0 );
+}
+
+/* Parse ServerHello message and configure context
+ *
+ * struct {
+ *    ProtocolVersion legacy_version = 0x0303; // TLS 1.2
+ *    Random random;
+ *    opaque legacy_session_id_echo<0..32>;
+ *    CipherSuite cipher_suite;
+ *    uint8 legacy_compression_method = 0;
+ *    Extension extensions<6..2^16-1>;
+ * } ServerHello;
+ */
+static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         const unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    const unsigned char *p = buf;
+    size_t extensions_len;
+    const unsigned char *extensions_end;
+    uint16_t cipher_suite;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+
+    /*
+     * Check there is space for minimal fields
+     *
+     * - legacy_version             ( 2 bytes)
+     * - random                     (MBEDTLS_SERVER_HELLO_RANDOM_LEN bytes)
+     * - legacy_session_id_echo     ( 1 byte ), minimum size
+     * - cipher_suite               ( 2 bytes)
+     * - legacy_compression_method  ( 1 byte )
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, MBEDTLS_SERVER_HELLO_RANDOM_LEN + 6 );
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "server hello", p, end - p );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, version", p, 2 );
+
+    /* ...
+     * ProtocolVersion legacy_version = 0x0303; // TLS 1.2
+     * ...
+     * with ProtocolVersion defined as:
+     * uint16 ProtocolVersion;
+     */
+    if( !( p[0] == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+           p[1] == MBEDTLS_SSL_MINOR_VERSION_3 ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unsupported version of TLS." ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION,
+                                      MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
+        return( MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION );
+    }
+    p += 2;
+
+    /* ...
+     * Random random;
+     * ...
+     * with Random defined as:
+     * opaque Random[MBEDTLS_SERVER_HELLO_RANDOM_LEN];
+     */
+    memcpy( &ssl->handshake->randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN], p,
+            MBEDTLS_SERVER_HELLO_RANDOM_LEN );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes",
+                           p, MBEDTLS_SERVER_HELLO_RANDOM_LEN );
+    p += MBEDTLS_SERVER_HELLO_RANDOM_LEN;
+
+    /* ...
+     * opaque legacy_session_id_echo<0..32>;
+     * ...
+     */
+    if( ssl_tls13_check_server_hello_session_id_echo( ssl, &p, end ) != 0 )
+    {
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    /* ...
+     * CipherSuite cipher_suite;
+     * ...
+     * with CipherSuite defined as:
+     * uint8 CipherSuite[2];
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
+    cipher_suite = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+
+
+    /*
+     * Check whether this ciphersuite is supported and offered.
+     * Via the force_ciphersuite version we may have instructed the client
+     * to use a different ciphersuite.
+     */
+    ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( cipher_suite );
+    if( ciphersuite_info == NULL ||
+        ssl_tls13_cipher_suite_is_offered( ssl, cipher_suite ) == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite(%04x) not found or not offered",
+                                    cipher_suite ) );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+
+    /* Configure ciphersuites */
+    mbedtls_ssl_optimize_checksum( ssl, ciphersuite_info );
+
+    ssl->handshake->ciphersuite_info = ciphersuite_info;
+    ssl->session_negotiate->ciphersuite = cipher_suite;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: ( %04x ) - %s",
+                                 cipher_suite, ciphersuite_info->name ) );
+
+#if defined(MBEDTLS_HAVE_TIME)
+    ssl->session_negotiate->start = time( NULL );
+#endif /* MBEDTLS_HAVE_TIME */
+
+    /* ...
+     * uint8 legacy_compression_method = 0;
+     * ...
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
+    if( p[0] != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad legacy compression method" ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+    p++;
+
+    /* ...
+     * Extension extensions<6..2^16-1>;
+     * ...
+     * struct {
+     *      ExtensionType extension_type; (2 bytes)
+     *      opaque extension_data<0..2^16-1>;
+     * } Extension;
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
+    extensions_len = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+
+    /* Check extensions do not go beyond the buffer of data. */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, extensions_len );
+    extensions_end = p + extensions_len;
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "server hello extensions", p, extensions_len );
+
+    while( p < extensions_end )
+    {
+        unsigned int extension_type;
+        size_t extension_data_len;
+
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, 4 );
+        extension_type = MBEDTLS_GET_UINT16_BE( p, 0 );
+        extension_data_len = MBEDTLS_GET_UINT16_BE( p, 2 );
+        p += 4;
+
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, extensions_end, extension_data_len );
+
+        switch( extension_type )
+        {
+            case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
+                MBEDTLS_SSL_DEBUG_MSG( 3,
+                            ( "found supported_versions extension" ) );
+
+                ret = ssl_tls13_parse_supported_versions_ext( ssl,
+                                                              p,
+                                                              p + extension_data_len );
+                if( ret != 0 )
+                    return( ret );
+                break;
+
+            case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension." ) );
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key:Not supported yet" ) );
+
+                MBEDTLS_SSL_PEND_FATAL_ALERT(
+                    MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
+                    MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
+                return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
+
+#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+            case MBEDTLS_TLS_EXT_KEY_SHARE:
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key_shares extension" ) );
+                if( ( ret = ssl_tls13_parse_key_share_ext( ssl,
+                                            p, p + extension_data_len ) ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET( 1,
+                                           "ssl_tls13_parse_key_share_ext",
+                                           ret );
+                    return( ret );
+                }
+                break;
+#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
+
+            default:
+                MBEDTLS_SSL_DEBUG_MSG(
+                    3,
+                    ( "unknown extension found: %u ( ignoring )",
+                      extension_type ) );
+
+                MBEDTLS_SSL_PEND_FATAL_ALERT(
+                    MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
+                    MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
+                return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
+        }
+
+        p += extension_data_len;
+    }
+
+    return( 0 );
+}
+
+static int ssl_tls13_finalize_server_hello( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_ssl_key_set traffic_keys;
+    mbedtls_ssl_transform *transform_handshake = NULL;
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+
+    /* Determine the key exchange mode:
+     * 1) If both the pre_shared_key and key_share extensions were received
+     *    then the key exchange mode is PSK with EPHEMERAL.
+     * 2) If only the pre_shared_key extension was received then the key
+     *    exchange mode is PSK-only.
+     * 3) If only the key_share extension was received then the key
+     *    exchange mode is EPHEMERAL-only.
+     */
+    switch( handshake->extensions_present &
+            ( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ) )
+    {
+        /* Only the pre_shared_key extension was received */
+        case MBEDTLS_SSL_EXT_PRE_SHARED_KEY:
+            handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK;
+            break;
+
+        /* Only the key_share extension was received */
+        case MBEDTLS_SSL_EXT_KEY_SHARE:
+            handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL;
+            break;
+
+        /* Both the pre_shared_key and key_share extensions were received */
+        case ( MBEDTLS_SSL_EXT_PRE_SHARED_KEY | MBEDTLS_SSL_EXT_KEY_SHARE ):
+            handshake->tls1_3_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
+            break;
+
+        /* Neither pre_shared_key nor key_share extension was received */
+        default:
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "Unknown key exchange." ) );
+            ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
+            goto cleanup;
+    }
+
+    /* Start the TLS 1.3 key schedule: Set the PSK and derive early secret.
+     *
+     * TODO: We don't have to do this in case we offered 0-RTT and the
+     *       server accepted it. In this case, we could skip generating
+     *       the early secret. */
+    ret = mbedtls_ssl_tls1_3_key_schedule_stage_early( ssl );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_key_schedule_stage_early_data",
+                               ret );
+        goto cleanup;
+    }
+
+    /* Compute handshake secret */
+    ret = mbedtls_ssl_tls13_key_schedule_stage_handshake( ssl );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_derive_master_secret", ret );
+        goto cleanup;
+    }
+
+    /* Next evolution in key schedule: Establish handshake secret and
+     * key material. */
+    ret = mbedtls_ssl_tls13_generate_handshake_keys( ssl, &traffic_keys );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_generate_handshake_keys",
+                               ret );
+        goto cleanup;
+    }
+
+    transform_handshake = mbedtls_calloc( 1, sizeof( mbedtls_ssl_transform ) );
+    if( transform_handshake == NULL )
+    {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto cleanup;
+    }
+
+    ret = mbedtls_ssl_tls13_populate_transform( transform_handshake,
+                              ssl->conf->endpoint,
+                              ssl->session_negotiate->ciphersuite,
+                              &traffic_keys,
+                              ssl );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_populate_transform", ret );
+        goto cleanup;
+    }
+
+    handshake->transform_handshake = transform_handshake;
+    mbedtls_ssl_set_inbound_transform( ssl, transform_handshake );
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "Switch to handshake keys for inbound traffic" ) );
+    ssl->session_in = ssl->session_negotiate;
+
+    /*
+     * State machine update
+     */
+    mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
+
+cleanup:
+
+    mbedtls_platform_zeroize( &traffic_keys, sizeof( traffic_keys ) );
+    if( ret != 0 )
+    {
+        mbedtls_free( transform_handshake );
+
+        MBEDTLS_SSL_PEND_FATAL_ALERT(
+            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
+            MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+    }
+    return( ret );
+}
+
+/*
+ * Wait and parse ServerHello handshake message.
  * Handler for MBEDTLS_SSL_SERVER_HELLO
  */
 static int ssl_tls1_3_process_server_hello( mbedtls_ssl_context *ssl )
 {
-    MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) );
-    mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_ENCRYPTED_EXTENSIONS );
-    return( 0 );
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *buf;
+    size_t buf_len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> %s", __func__ ) );
+
+    /* Coordination step
+     * - Fetch record
+     * - Make sure it's either a ServerHello or a HRR.
+     * - Switch processing routine in case of HRR
+     */
+    ssl->major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
+    ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
+
+    ret = ssl_tls13_server_hello_coordinate( ssl, &buf, &buf_len );
+    /* Parsing step
+     * We know what message to expect by now and call
+     * the respective parsing function.
+     */
+    if( ret == SSL_SERVER_HELLO_COORDINATE_HELLO )
+    {
+        MBEDTLS_SSL_PROC_CHK( ssl_tls13_parse_server_hello( ssl, buf,
+                                                            buf + buf_len ) );
+
+        mbedtls_ssl_tls1_3_add_hs_msg_to_checksum( ssl,
+                                                   MBEDTLS_SSL_HS_SERVER_HELLO,
+                                                   buf, buf_len );
+
+        MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_server_hello( ssl ) );
+    }
+    else if( ret == SSL_SERVER_HELLO_COORDINATE_HRR )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "HRR not supported" ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ,
+                                      MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
+    }
+
+cleanup:
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= %s", __func__ ) );
+    return( ret );
 }
 
 /*
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index b07c1c3..96f5310 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -826,17 +826,18 @@
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_md_type_t md_type;
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
 
-    if( ssl->handshake->ciphersuite_info == NULL )
+    if( handshake->ciphersuite_info == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher suite info not found" ) );
         return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
     }
 
-    md_type = ssl->handshake->ciphersuite_info->mac;
+    md_type = handshake->ciphersuite_info->mac;
 
     ret = mbedtls_ssl_tls1_3_evolve_secret( md_type, NULL, NULL, 0,
-                                ssl->handshake->tls1_3_master_secrets.early );
+                                            handshake->tls1_3_master_secrets.early );
     if( ret != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
@@ -846,4 +847,185 @@
     return( 0 );
 }
 
+/* mbedtls_ssl_tls13_generate_handshake_keys() generates keys necessary for
+ * protecting the handshake messages, as described in Section 7 of TLS 1.3. */
+int mbedtls_ssl_tls13_generate_handshake_keys( mbedtls_ssl_context *ssl,
+                                               mbedtls_ssl_key_set *traffic_keys )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    mbedtls_md_type_t md_type;
+    mbedtls_md_info_t const *md_info;
+    size_t md_size;
+
+    unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE];
+    size_t transcript_len;
+
+    mbedtls_cipher_info_t const *cipher_info;
+    size_t keylen, ivlen;
+
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info;
+    mbedtls_ssl_tls1_3_handshake_secrets *tls13_hs_secrets = &handshake->tls13_hs_secrets;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_tls13_generate_handshake_keys" ) );
+
+    cipher_info = mbedtls_cipher_info_from_type( ciphersuite_info->cipher );
+    keylen = cipher_info->key_bitlen >> 3;
+    ivlen = cipher_info->iv_size;
+
+    md_type = ciphersuite_info->mac;
+    md_info = mbedtls_md_info_from_type( md_type );
+    md_size = mbedtls_md_get_size( md_info );
+
+    ret = mbedtls_ssl_get_handshake_transcript( ssl, md_type,
+                                                transcript,
+                                                sizeof( transcript ),
+                                                &transcript_len );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1,
+                               "mbedtls_ssl_get_handshake_transcript",
+                               ret );
+        return( ret );
+    }
+
+    ret = mbedtls_ssl_tls1_3_derive_handshake_secrets( md_type,
+                                    handshake->tls1_3_master_secrets.handshake,
+                                    transcript, transcript_len, tls13_hs_secrets );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_derive_handshake_secrets",
+                               ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "Client handshake traffic secret",
+                    tls13_hs_secrets->client_handshake_traffic_secret,
+                    md_size );
+    MBEDTLS_SSL_DEBUG_BUF( 4, "Server handshake traffic secret",
+                    tls13_hs_secrets->server_handshake_traffic_secret,
+                    md_size );
+
+    /*
+     * Export client handshake traffic secret
+     */
+    if( ssl->f_export_keys != NULL )
+    {
+        ssl->f_export_keys( ssl->p_export_keys,
+                MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_HANDSHAKE_TRAFFIC_SECRET,
+                tls13_hs_secrets->client_handshake_traffic_secret,
+                md_size,
+                handshake->randbytes + 32,
+                handshake->randbytes,
+                MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ );
+
+        ssl->f_export_keys( ssl->p_export_keys,
+                MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_HANDSHAKE_TRAFFIC_SECRET,
+                tls13_hs_secrets->server_handshake_traffic_secret,
+                md_size,
+                handshake->randbytes + 32,
+                handshake->randbytes,
+                MBEDTLS_SSL_TLS_PRF_NONE /* TODO: FIX! */ );
+    }
+
+    ret = mbedtls_ssl_tls1_3_make_traffic_keys( md_type,
+                            tls13_hs_secrets->client_handshake_traffic_secret,
+                            tls13_hs_secrets->server_handshake_traffic_secret,
+                            md_size, keylen, ivlen, traffic_keys );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_make_traffic_keys", ret );
+        goto exit;
+    }
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "client_handshake write_key",
+                           traffic_keys->client_write_key,
+                           traffic_keys->key_len);
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "server_handshake write_key",
+                           traffic_keys->server_write_key,
+                           traffic_keys->key_len);
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "client_handshake write_iv",
+                           traffic_keys->client_write_iv,
+                           traffic_keys->iv_len);
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "server_handshake write_iv",
+                           traffic_keys->server_write_iv,
+                           traffic_keys->iv_len);
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_tls13_generate_handshake_keys" ) );
+
+exit:
+
+    return( ret );
+}
+
+int mbedtls_ssl_tls13_key_schedule_stage_handshake( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+    mbedtls_md_type_t const md_type = handshake->ciphersuite_info->mac;
+    size_t ephemeral_len = 0;
+    unsigned char ecdhe[MBEDTLS_ECP_MAX_BYTES];
+#if defined(MBEDTLS_DEBUG_C)
+    mbedtls_md_info_t const * const md_info = mbedtls_md_info_from_type( md_type );
+    size_t const md_size = mbedtls_md_get_size( md_info );
+#endif /* MBEDTLS_DEBUG_C */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED)
+    /*
+     * Compute ECDHE secret used to compute the handshake secret from which
+     * client_handshake_traffic_secret and server_handshake_traffic_secret
+     * are derived in the handshake secret derivation stage.
+     */
+    if( mbedtls_ssl_tls1_3_ephemeral_enabled( ssl ) )
+    {
+        if( mbedtls_ssl_tls13_named_group_is_ecdhe( handshake->offered_group_id ) )
+        {
+#if defined(MBEDTLS_ECDH_C)
+            ret = mbedtls_ecdh_calc_secret( &handshake->ecdh_ctx,
+                                            &ephemeral_len, ecdhe, sizeof( ecdhe ),
+                                            ssl->conf->f_rng,
+                                            ssl->conf->p_rng );
+            if( ret != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
+                return( ret );
+            }
+#endif /* MBEDTLS_ECDH_C */
+        }
+        else if( mbedtls_ssl_tls13_named_group_is_dhe( handshake->offered_group_id ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "DHE not supported." ) );
+            return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+        }
+    }
+#else
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */
+
+    /*
+     * Compute the Handshake Secret
+     */
+    ret = mbedtls_ssl_tls1_3_evolve_secret( md_type,
+                                            handshake->tls1_3_master_secrets.early,
+                                            ecdhe, ephemeral_len,
+                                            handshake->tls1_3_master_secrets.handshake );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls1_3_evolve_secret", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_BUF( 4, "Handshake secret",
+                           handshake->tls1_3_master_secrets.handshake, md_size );
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED)
+    mbedtls_platform_zeroize( ecdhe, sizeof( ecdhe ) );
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDHE_ENABLED */
+    return( 0 );
+}
+
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 866aae9..384f433 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.
  *
@@ -553,4 +532,37 @@
  */
 int mbedtls_ssl_tls1_3_key_schedule_stage_early( mbedtls_ssl_context *ssl );
 
+/**
+ * \brief Transition into handshake stage of TLS 1.3 key schedule.
+ *
+ *        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 Early -> Handshake transition.
+ *
+ *        In the handshake stage, mbedtls_ssl_tls13_generate_handshake_keys()
+ *        can be used to derive the handshake traffic keys.
+ *
+ * \param ssl  The SSL context to operate on. This must be in key schedule
+ *             stage \c Early.
+ *
+ * \returns    \c 0 on success.
+ * \returns    A negative error code on failure.
+ */
+int mbedtls_ssl_tls13_key_schedule_stage_handshake( 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 */
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index d66c57a..8fbe677 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -8806,9 +8806,10 @@
 
 requires_openssl_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL
+requires_config_disabled MBEDTLS_USE_PSA_CRYPTO
 run_test    "TLS1.3: Test client hello msg work - openssl" \
             "$O_NEXT_SRV -tls1_3 -msg" \
-            "$P_CLI debug_level=2 min_version=tls1_3 max_version=tls1_3" \
+            "$P_CLI debug_level=3 min_version=tls1_3 max_version=tls1_3" \
             1 \
             -c "SSL - The requested feature is not available" \
             -s "ServerHello"                \
@@ -8823,13 +8824,18 @@
             -c "tls1_3 client state: 20"    \
             -c "tls1_3 client state: 11"    \
             -c "tls1_3 client state: 14"    \
-            -c "tls1_3 client state: 15"
+            -c "tls1_3 client state: 15"    \
+            -c "<= ssl_tls1_3_process_server_hello" \
+            -c "server hello, chosen ciphersuite: ( 1301 ) - TLS1-3-AES-128-GCM-SHA256" \
+            -c "ECDH curve: x25519"         \
+            -c "=> ssl_tls1_3_process_server_hello"
 
 requires_gnutls_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL
+requires_config_disabled MBEDTLS_USE_PSA_CRYPTO
 run_test    "TLS1.3: Test client hello msg work - gnutls" \
             "$G_NEXT_SRV --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3 --debug=4" \
-            "$P_CLI debug_level=2 min_version=tls1_3 max_version=tls1_3" \
+            "$P_CLI debug_level=3 min_version=tls1_3 max_version=tls1_3" \
             1 \
             -c "SSL - The requested feature is not available" \
             -s "SERVER HELLO was queued"    \
@@ -8844,7 +8850,12 @@
             -c "tls1_3 client state: 20"    \
             -c "tls1_3 client state: 11"    \
             -c "tls1_3 client state: 14"    \
-            -c "tls1_3 client state: 15"
+            -c "tls1_3 client state: 15"    \
+            -c "<= ssl_tls1_3_process_server_hello" \
+            -c "server hello, chosen ciphersuite: ( 1301 ) - TLS1-3-AES-128-GCM-SHA256" \
+            -c "ECDH curve: x25519"         \
+            -c "=> ssl_tls1_3_process_server_hello"
+
 
 # Test heap memory usage after handshake
 requires_config_enabled MBEDTLS_MEMORY_DEBUG