From 6dcd18d55bb3560c023e09f5d24cd65f5426d855 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Sun, 10 Jul 2022 06:32:05 +0000
Subject: [PATCH 01/19] export hdr checksum function

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_misc.h | 4 ++++
 library/ssl_tls.c  | 6 +++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index d16b254fc7..381f0c4bfa 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -1349,6 +1349,10 @@ void mbedtls_ssl_add_hs_msg_to_checksum( mbedtls_ssl_context *ssl,
                                          unsigned char const *msg,
                                          size_t msg_len );
 
+void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
+                                         unsigned hs_type,
+                                         size_t total_hs_len );
+
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
 #if !defined(MBEDTLS_USE_PSA_CRYPTO)
 MBEDTLS_CHECK_RETURN_CRITICAL
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index e60b82fa5f..5a72fede49 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -532,9 +532,9 @@ void mbedtls_ssl_optimize_checksum( mbedtls_ssl_context *ssl,
     }
 }
 
-static void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
-                                                unsigned hs_type,
-                                                size_t total_hs_len )
+void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
+                                         unsigned hs_type,
+                                         size_t total_hs_len )
 {
     unsigned char hs_hdr[4];
 

From 1c105560b426272cae25c12fa1a90dcc320d65cb Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Sun, 10 Jul 2022 06:32:38 +0000
Subject: [PATCH 02/19] add offered psks parser

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls.c          |   3 +-
 library/ssl_tls13_server.c | 327 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 322 insertions(+), 8 deletions(-)

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 5a72fede49..cf9583ccb7 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1710,7 +1710,8 @@ int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl,
     else
         alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
 
-    psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
+    psa_set_key_usage_flags( &key_attributes,
+                             PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT );
     psa_set_key_algorithm( &key_attributes, alg );
     psa_set_key_type( &key_attributes, PSA_KEY_TYPE_DERIVE );
 
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 02a2850edf..104d5b62b9 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -24,6 +24,7 @@
 #include "mbedtls/debug.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform.h"
+#include "mbedtls/constant_time.h"
 
 #include "ssl_misc.h"
 #include "ssl_tls13_keys.h"
@@ -97,6 +98,269 @@ static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
     ssl->handshake->tls13_kex_modes = ke_modes;
     return( 0 );
 }
+
+#define SSL_TLS1_3_OFFERED_PSK_NOT_MATCH   0
+#define SSL_TLS1_3_OFFERED_PSK_MATCH       1
+static int ssl_tls13_offered_psks_check_identity_match(
+               mbedtls_ssl_context *ssl,
+               const unsigned char *identity,
+               uint16_t identity_len )
+{
+    /* Check identity with external configured function */
+    if( ssl->conf->f_psk != NULL )
+    {
+        if( ssl->conf->f_psk(
+                ssl->conf->p_psk, ssl, identity, identity_len ) == 0 )
+        {
+            return( SSL_TLS1_3_OFFERED_PSK_MATCH );
+        }
+        return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
+    }
+
+    /* Check identity with pre-configured psk */
+    if( identity_len == ssl->conf->psk_identity_len &&
+        mbedtls_ct_memcmp( ssl->conf->psk_identity,
+                            identity, identity_len ) == 0 )
+    {
+        mbedtls_ssl_set_hs_psk( ssl, ssl->conf->psk, ssl->conf->psk_len );
+        return( SSL_TLS1_3_OFFERED_PSK_MATCH );
+    }
+
+    /* Add session ticket here */
+
+    return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
+}
+
+static int ssl_tls13_offered_psks_check_binder_match(
+               mbedtls_ssl_context *ssl,
+               const unsigned char *binder,
+               uint16_t binder_len,
+               const unsigned char *psk,
+               size_t psk_len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    int psk_type;
+    mbedtls_md_type_t md_alg =
+        binder_len == 32 ? MBEDTLS_MD_SHA256 : MBEDTLS_MD_SHA384 ;
+    psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg );
+    unsigned char transcript[MBEDTLS_MD_MAX_SIZE];
+    size_t transcript_len;
+    unsigned char server_computed_binder[MBEDTLS_MD_MAX_SIZE];
+
+    if( ssl->handshake->resume == 1 )
+        psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION;
+    else
+        psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
+
+    /* Get current state of handshake transcript. */
+    ret = mbedtls_ssl_get_handshake_transcript( ssl, md_alg,
+                                                transcript, sizeof( transcript ),
+                                                &transcript_len );
+    if( ret != 0 )
+        return( ret );
+
+    ret = mbedtls_ssl_tls13_create_psk_binder( ssl, psa_md_alg,
+                                               psk, psk_len, psk_type,
+                                               transcript,
+                                               server_computed_binder );
+    /* We do not check for multiple binders */
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "PSK binder calculation failed." ) );
+        return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+    }
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( computed ): ",
+                           server_computed_binder, binder_len );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( received ): ", binder, binder_len );
+
+    if( mbedtls_ct_memcmp( server_computed_binder, binder, binder_len ) == 0 )
+    {
+        return( SSL_TLS1_3_OFFERED_PSK_MATCH );
+    }
+
+    return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
+}
+/* Parser for pre_shared_key extension in client hello
+ *    struct {
+ *        opaque identity<1..2^16-1>;
+ *        uint32 obfuscated_ticket_age;
+ *    } PskIdentity;
+ *
+ *    opaque PskBinderEntry<32..255>;
+ *
+ *    struct {
+ *        PskIdentity identities<7..2^16-1>;
+ *        PskBinderEntry binders<33..2^16-1>;
+ *    } OfferedPsks;
+ *
+ *    struct {
+ *        select (Handshake.msg_type) {
+ *            case client_hello: OfferedPsks;
+ *            ....
+ *        };
+ *    } PreSharedKeyExtension;
+ */
+static int ssl_tls13_parse_offered_psks_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 identities_len;
+    const unsigned char *identities_end;
+    uint32_t identity_matched = SSL_TLS1_3_OFFERED_PSK_NOT_MATCH;
+    uint16_t binders_len;
+    const unsigned char *binders_end;
+    unsigned char *psk = NULL;
+    size_t psk_len = 0;
+    int binder_matched = 0;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_status_t status;
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extesion", buf, end - buf );
+
+    /* identities   >= 7 bytes */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 7 );
+
+    identities_len = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, identities_len );
+    identities_end = p + identities_len;
+
+    while( p < identities_end )
+    {
+        uint16_t identity_len;
+        const unsigned char *identity;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, identities_end, 2 );
+        identity_len = MBEDTLS_GET_UINT16_BE( p, 0 );
+        p += 2;
+        identity = p;
+        p += identity_len;
+        p += 4; // skip obfuscated_ticket_age
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len );
+
+        if( identity_matched == SSL_TLS1_3_OFFERED_PSK_MATCH )
+            continue;
+
+        MBEDTLS_SSL_DEBUG_BUF( 3, "received psk identity",
+                               identity, identity_len );
+        identity_matched = ssl_tls13_offered_psks_check_identity_match(
+                              ssl, identity, identity_len );
+    }
+
+    if( identity_matched != SSL_TLS1_3_OFFERED_PSK_MATCH )
+    {
+        MBEDTLS_SSL_PEND_FATAL_ALERT(
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY );
+        return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
+    }
+
+    if( p != identities_end )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
+                                      MBEDTLS_ERR_SSL_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+    }
+
+    ssl->handshake->update_checksum( ssl, buf, p - buf );
+
+    /* binders      >= 33 bytes */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 33 );
+    binders_len = MBEDTLS_GET_UINT16_BE( p, 0 );
+    p += 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binders_len );
+    binders_end = p + binders_len;
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    status = psa_get_key_attributes( ssl->handshake->psk_opaque,
+                                         &key_attributes );
+    if( status != PSA_SUCCESS)
+    {
+        return( psa_ssl_status_to_mbedtls( status ) );
+    }
+
+    psk_len = PSA_BITS_TO_BYTES(psa_get_key_bits( &key_attributes ) );
+    psk = mbedtls_calloc( 1, psk_len );
+    if( psk == NULL )
+    {
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+    status = psa_export_key(ssl->handshake->psk_opaque, psk, psk_len, &psk_len );
+    if( status != PSA_SUCCESS)
+    {
+        ret = psa_ssl_status_to_mbedtls( status );
+        goto exit_failue;
+    }
+#else
+    psk = ssl->handshake->psk;
+    psk_len = ssl->handshake->psk_len;
+#endif /* !MBEDTLS_USE_PSA_CRYPTO */
+
+    while( p < binders_end )
+    {
+        uint8_t binder_len;
+        const unsigned char *binder;
+
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
+        binder_len = *p++;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binder_len );
+        binder = p;
+        p += binder_len;
+
+        if( binder_matched == SSL_TLS1_3_OFFERED_PSK_MATCH)
+            continue;
+
+        binder_matched = ssl_tls13_offered_psks_check_binder_match(
+                              ssl, binder, binder_len, psk, psk_len );
+        if( binder_matched < 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1,
+                "ssl_tls13_offered_psks_check_binder_match" , binder_matched );
+            MBEDTLS_SSL_PEND_FATAL_ALERT(
+                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
+                MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+            ret = binder_matched;
+            goto exit_failue;
+        }
+    }
+
+    if( binder_matched != SSL_TLS1_3_OFFERED_PSK_MATCH )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "Received psk binder does not match computed psk binder." ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT(
+            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
+            MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
+        goto exit_failue;
+    }
+
+    if( p != binders_end )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
+                                      MBEDTLS_ERR_SSL_DECODE_ERROR );
+        ret = MBEDTLS_ERR_SSL_DECODE_ERROR;
+        goto exit_failue;
+    }
+
+    /* Update the handshake transcript with the binder list. */
+    ssl->handshake->update_checksum( ssl,
+                                     identities_end,
+                                     (size_t)( p - identities_end ) );
+    ret = 0;
+
+exit_failue:
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_free( (void *)psk );
+#endif
+    return( ret );
+}
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 /* From RFC 8446:
@@ -540,6 +804,10 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
     int hrr_required = 0;
 
     const mbedtls_ssl_ciphersuite_t* ciphersuite_info;
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    const unsigned char *pre_shared_key_ext_start = NULL;
+    const unsigned char *pre_shared_key_ext_end = NULL;
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
     ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
 
@@ -825,6 +1093,20 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
                 break;
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+            case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
+                /* Delay processing of the PSK identity once we have
+                 * found out which algorithms to use. We keep a pointer
+                 * to the buffer and the size for later processing.
+                 */
+                pre_shared_key_ext_start = p;
+                pre_shared_key_ext_end = extension_data_end;
+
+                ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
+                break;
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
 #if defined(MBEDTLS_SSL_ALPN)
             case MBEDTLS_TLS_EXT_ALPN:
                 MBEDTLS_SSL_DEBUG_MSG( 3, ( "found alpn extension" ) );
@@ -866,17 +1148,48 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
         p += extension_data_len;
     }
 
+
+#if defined(MBEDTLS_DEBUG_C)
+    /* List all the extensions we have received */
+    ssl_tls13_debug_print_client_hello_exts( ssl );
+#endif /* MBEDTLS_DEBUG_C */
+
+    mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
+                                        MBEDTLS_SSL_HS_CLIENT_HELLO,
+                                        p - buf );
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
     /* Update checksum with either
      * - The entire content of the CH message, if no PSK extension is present
      * - The content up to but excluding the PSK extension, if present.
      */
-    mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
-                                        buf, p - buf );
-
-    /* List all the extensions we have received */
-#if defined(MBEDTLS_DEBUG_C)
-    ssl_tls13_debug_print_client_hello_exts( ssl );
-#endif /* MBEDTLS_DEBUG_C */
+    /* If we've settled on a PSK-based exchange, parse PSK identity ext */
+    if( mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) &&
+        ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) )
+    {
+        ssl->handshake->update_checksum( ssl, buf,
+                                         pre_shared_key_ext_start - buf );
+        ret = ssl_tls13_parse_offered_psks_ext( ssl,
+                                                pre_shared_key_ext_start,
+                                                pre_shared_key_ext_end );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_offered_psks_ext" ),
+                                   ret );
+            return( ret );
+        }
+        /* If pre_shared_key is not last extension */
+        if( p - pre_shared_key_ext_end )
+        {
+            ssl->handshake->update_checksum( ssl,
+                                             pre_shared_key_ext_end,
+                                             p - pre_shared_key_ext_end );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+    {
+        ssl->handshake->update_checksum( ssl, buf, p - buf );
+    }
 
     return( hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK );
 }

From 36847820fa8689045d3fb465efcd3551eda48667 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Sun, 10 Jul 2022 06:35:06 +0000
Subject: [PATCH 03/19] add tests for offered psk parser

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 tests/ssl-opt.sh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 942d705242..20b4da9c93 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -2283,6 +2283,8 @@ run_test    "TLS 1.3: key exchange mode parameter passing: All" \
             "$P_CLI tls13_kex_modes=all" \
             0
 
+# FIXME: force_ciphersuite=TLS1-3-AES-128-GCM-SHA256 should be removed in future
+#        Without it, the binder will generate wrong value.
 requires_openssl_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
@@ -2296,6 +2298,8 @@ run_test    "TLS 1.3: psk_key_exchange_modes: basic check, O->m" \
             -s "Found PSK_EPHEMERAL KEX MODE" \
             -s "Found PSK KEX MODE"
 
+# FIXME: force_ciphersuite=TLS1-3-AES-128-GCM-SHA256 should be removed in future
+#        Without it, the binder will generate wrong value.
 requires_gnutls_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE

From 032b15ce5e56af8f97d10e652e995bf4fb19cad5 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Mon, 11 Jul 2022 06:10:03 +0000
Subject: [PATCH 04/19] Add write selected_identity

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 71 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 104d5b62b9..eff79ba815 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -361,6 +361,61 @@ exit_failue:
 #endif
     return( ret );
 }
+
+/*
+ * struct {
+ *   select ( Handshake.msg_type ) {
+ *      ....
+ *      case server_hello:
+ *          uint16 selected_identity;
+ *   }
+ * } PreSharedKeyExtension;
+ */
+static int ssl_tls13_write_selected_identity_ext( mbedtls_ssl_context *ssl,
+                                                      unsigned char *buf,
+                                                      unsigned char *end,
+                                                      size_t *olen )
+{
+    unsigned char *p = (unsigned char*)buf;
+    size_t selected_identity;
+
+    *olen = 0;
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    if( mbedtls_svc_key_id_is_null( ssl->handshake->psk_opaque ) )
+#else
+    if( ssl->handshake->psk == NULL )
+#endif
+    {
+        /* We shouldn't have called this extension writer unless we've
+         * chosen to use a PSK. */
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding pre_shared_key extension" ) );
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
+
+    /* Extension Type */
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0 );
+
+    /* Extension Length */
+    MBEDTLS_PUT_UINT16_BE( 2, p, 2 );
+
+    /* NOTE: This will need to be adjusted once we support multiple PSKs
+     *       being offered by the client. */
+    selected_identity = 0;
+
+    /* Write selected_identity */
+    MBEDTLS_PUT_UINT16_BE( selected_identity, p, 4 );
+
+    *olen = 6;
+
+    MBEDTLS_SSL_DEBUG_MSG( 4, ( "sent selected_identity: %" MBEDTLS_PRINTF_SIZET,
+                                selected_identity ) );
+
+    return( 0 );
+}
+
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 /* From RFC 8446:
@@ -1157,6 +1212,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
     mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
                                         MBEDTLS_SSL_HS_CLIENT_HELLO,
                                         p - buf );
+
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
     /* Update checksum with either
      * - The entire content of the CH message, if no PSK extension is present
@@ -1645,6 +1701,21 @@ static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
         p += output_len;
     }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    MBEDTLS_SSL_DEBUG_MSG( 2,( " mbedtls_ssl_tls13_some_psk_enabled %d", mbedtls_ssl_tls13_some_psk_enabled( ssl ) ) );
+    if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) )
+    {
+        ret = ssl_tls13_write_selected_identity_ext( ssl, p, end, &output_len );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_selected_identity_ext",
+                                   ret );
+            return( ret );
+        }
+        p += output_len;
+    }
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
     MBEDTLS_PUT_UINT16_BE( p - p_extensions_len - 2, p_extensions_len, 0 );
 
     MBEDTLS_SSL_DEBUG_BUF( 4, "server hello extensions",

From 997549353ed02a4ebe696af303bfd4ed0a396282 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 15 Jul 2022 15:01:08 +0800
Subject: [PATCH 05/19] fix various code format issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index eff79ba815..ec1df2a781 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -372,9 +372,9 @@ exit_failue:
  * } PreSharedKeyExtension;
  */
 static int ssl_tls13_write_selected_identity_ext( mbedtls_ssl_context *ssl,
-                                                      unsigned char *buf,
-                                                      unsigned char *end,
-                                                      size_t *olen )
+                                                  unsigned char *buf,
+                                                  unsigned char *end,
+                                                  size_t *olen )
 {
     unsigned char *p = (unsigned char*)buf;
     size_t selected_identity;
@@ -395,17 +395,12 @@ static int ssl_tls13_write_selected_identity_ext( mbedtls_ssl_context *ssl,
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding pre_shared_key extension" ) );
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
 
-    /* Extension Type */
     MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0 );
-
-    /* Extension Length */
     MBEDTLS_PUT_UINT16_BE( 2, p, 2 );
 
     /* NOTE: This will need to be adjusted once we support multiple PSKs
      *       being offered by the client. */
     selected_identity = 0;
-
-    /* Write selected_identity */
     MBEDTLS_PUT_UINT16_BE( selected_identity, p, 4 );
 
     *olen = 6;
@@ -702,9 +697,9 @@ static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(
         mbedtls_ssl_context *ssl )
 {
     return( ssl_tls13_client_hello_has_exts( ssl,
-                          MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
-                          MBEDTLS_SSL_EXT_KEY_SHARE        |
-                          MBEDTLS_SSL_EXT_SIG_ALG ) );
+                                             MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
+                                             MBEDTLS_SSL_EXT_KEY_SHARE        |
+                                             MBEDTLS_SSL_EXT_SIG_ALG ) );
 }
 
 MBEDTLS_CHECK_RETURN_CRITICAL
@@ -1702,7 +1697,8 @@ static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
     }
 
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
-    MBEDTLS_SSL_DEBUG_MSG( 2,( " mbedtls_ssl_tls13_some_psk_enabled %d", mbedtls_ssl_tls13_some_psk_enabled( ssl ) ) );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( " mbedtls_ssl_tls13_some_psk_enabled %d",
+                                mbedtls_ssl_tls13_some_psk_enabled( ssl ) ) );
     if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) )
     {
         ret = ssl_tls13_write_selected_identity_ext( ssl, p, end, &output_len );

From 4a2ea16aedc53591a195301b44edcb7d7b9a8490 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 15 Jul 2022 15:01:26 +0800
Subject: [PATCH 06/19] remove forcecipher for psk test

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 tests/ssl-opt.sh | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 20b4da9c93..942d705242 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -2283,8 +2283,6 @@ run_test    "TLS 1.3: key exchange mode parameter passing: All" \
             "$P_CLI tls13_kex_modes=all" \
             0
 
-# FIXME: force_ciphersuite=TLS1-3-AES-128-GCM-SHA256 should be removed in future
-#        Without it, the binder will generate wrong value.
 requires_openssl_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
@@ -2298,8 +2296,6 @@ run_test    "TLS 1.3: psk_key_exchange_modes: basic check, O->m" \
             -s "Found PSK_EPHEMERAL KEX MODE" \
             -s "Found PSK KEX MODE"
 
-# FIXME: force_ciphersuite=TLS1-3-AES-128-GCM-SHA256 should be removed in future
-#        Without it, the binder will generate wrong value.
 requires_gnutls_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE

From 6e74a7e3c7132b892d6a21200014b66ad64338be Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Wed, 20 Jul 2022 20:49:32 +0800
Subject: [PATCH 07/19] Add check return flags

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index ec1df2a781..6280f72eb3 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -54,6 +54,7 @@
  *       PskKeyExchangeMode ke_modes<1..255>;
  *   } PskKeyExchangeModes;
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
                                                    const unsigned char *buf,
                                                    const unsigned char *end )
@@ -101,6 +102,7 @@ static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
 
 #define SSL_TLS1_3_OFFERED_PSK_NOT_MATCH   0
 #define SSL_TLS1_3_OFFERED_PSK_MATCH       1
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_offered_psks_check_identity_match(
                mbedtls_ssl_context *ssl,
                const unsigned char *identity,
@@ -131,6 +133,7 @@ static int ssl_tls13_offered_psks_check_identity_match(
     return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_offered_psks_check_binder_match(
                mbedtls_ssl_context *ssl,
                const unsigned char *binder,
@@ -201,6 +204,7 @@ static int ssl_tls13_offered_psks_check_binder_match(
  *        };
  *    } PreSharedKeyExtension;
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_parse_offered_psks_ext( mbedtls_ssl_context *ssl,
                                              const unsigned char *buf,
                                              const unsigned char *end )

From bb852029f4d18290be111c943b290d173d72d09b Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Wed, 20 Jul 2022 21:10:44 +0800
Subject: [PATCH 08/19] fix naming issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 6280f72eb3..4d8302bc0b 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -205,9 +205,9 @@ static int ssl_tls13_offered_psks_check_binder_match(
  *    } PreSharedKeyExtension;
  */
 MBEDTLS_CHECK_RETURN_CRITICAL
-static int ssl_tls13_parse_offered_psks_ext( mbedtls_ssl_context *ssl,
-                                             const unsigned char *buf,
-                                             const unsigned char *end )
+static int ssl_tls13_parse_pre_shared_key_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;
@@ -238,6 +238,7 @@ static int ssl_tls13_parse_offered_psks_ext( mbedtls_ssl_context *ssl,
     {
         uint16_t identity_len;
         const unsigned char *identity;
+
         MBEDTLS_SSL_CHK_BUF_READ_PTR( p, identities_end, 2 );
         identity_len = MBEDTLS_GET_UINT16_BE( p, 0 );
         p += 2;
@@ -375,10 +376,10 @@ exit_failue:
  *   }
  * } PreSharedKeyExtension;
  */
-static int ssl_tls13_write_selected_identity_ext( mbedtls_ssl_context *ssl,
-                                                  unsigned char *buf,
-                                                  unsigned char *end,
-                                                  size_t *olen )
+static int ssl_tls13_write_server_pre_shared_key_ext( mbedtls_ssl_context *ssl,
+                                                      unsigned char *buf,
+                                                      unsigned char *end,
+                                                      size_t *olen )
 {
     unsigned char *p = (unsigned char*)buf;
     size_t selected_identity;
@@ -1223,12 +1224,12 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
     {
         ssl->handshake->update_checksum( ssl, buf,
                                          pre_shared_key_ext_start - buf );
-        ret = ssl_tls13_parse_offered_psks_ext( ssl,
-                                                pre_shared_key_ext_start,
-                                                pre_shared_key_ext_end );
+        ret = ssl_tls13_parse_pre_shared_key_ext( ssl,
+                                                  pre_shared_key_ext_start,
+                                                  pre_shared_key_ext_end );
         if( ret != 0 )
         {
-            MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_offered_psks_ext" ),
+            MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_pre_shared_key_ext" ),
                                    ret );
             return( ret );
         }
@@ -1705,10 +1706,10 @@ static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
                                 mbedtls_ssl_tls13_some_psk_enabled( ssl ) ) );
     if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) )
     {
-        ret = ssl_tls13_write_selected_identity_ext( ssl, p, end, &output_len );
+        ret = ssl_tls13_write_server_pre_shared_key_ext( ssl, p, end, &output_len );
         if( ret != 0 )
         {
-            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_selected_identity_ext",
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls13_write_server_pre_shared_key_ext",
                                    ret );
             return( ret );
         }

From daf375aa8be4658a92e3b917fef353ac4a47d750 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Wed, 20 Jul 2022 21:31:43 +0800
Subject: [PATCH 09/19] fix issues of check_binder_match

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 4d8302bc0b..c50b20265a 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -146,14 +146,11 @@ static int ssl_tls13_offered_psks_check_binder_match(
     mbedtls_md_type_t md_alg =
         binder_len == 32 ? MBEDTLS_MD_SHA256 : MBEDTLS_MD_SHA384 ;
     psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg );
-    unsigned char transcript[MBEDTLS_MD_MAX_SIZE];
+    unsigned char transcript[PSA_HASH_MAX_SIZE];
     size_t transcript_len;
-    unsigned char server_computed_binder[MBEDTLS_MD_MAX_SIZE];
+    unsigned char server_computed_binder[PSA_HASH_MAX_SIZE];
 
-    if( ssl->handshake->resume == 1 )
-        psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION;
-    else
-        psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
+    psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
 
     /* Get current state of handshake transcript. */
     ret = mbedtls_ssl_get_handshake_transcript( ssl, md_alg,
@@ -182,6 +179,8 @@ static int ssl_tls13_offered_psks_check_binder_match(
         return( SSL_TLS1_3_OFFERED_PSK_MATCH );
     }
 
+    mbedtls_platform_zeroize( server_computed_binder,
+                              sizeof( server_computed_binder ) );
     return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
 }
 /* Parser for pre_shared_key extension in client hello

From 352cd7db59d431437ec9f780cd1ecd3da69e6856 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Wed, 20 Jul 2022 22:11:00 +0800
Subject: [PATCH 10/19] fix various issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index c50b20265a..89a718b4d4 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -128,8 +128,6 @@ static int ssl_tls13_offered_psks_check_identity_match(
         return( SSL_TLS1_3_OFFERED_PSK_MATCH );
     }
 
-    /* Add session ticket here */
-
     return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
 }
 
@@ -242,9 +240,10 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         identity_len = MBEDTLS_GET_UINT16_BE( p, 0 );
         p += 2;
         identity = p;
-        p += identity_len;
-        p += 4; // skip obfuscated_ticket_age
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len );
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( identity,
+                                      identities_end,
+                                      identity_len + 4  );
+        p += identity_len + 4;
 
         if( identity_matched == SSL_TLS1_3_OFFERED_PSK_MATCH )
             continue;
@@ -258,8 +257,8 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     if( identity_matched != SSL_TLS1_3_OFFERED_PSK_MATCH )
     {
         MBEDTLS_SSL_PEND_FATAL_ALERT(
-            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY );
+            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY,
+            MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
         return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
     }
 
@@ -298,7 +297,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     if( status != PSA_SUCCESS)
     {
         ret = psa_ssl_status_to_mbedtls( status );
-        goto exit_failue;
+        goto exit_failure;
     }
 #else
     psk = ssl->handshake->psk;
@@ -310,9 +309,9 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         uint8_t binder_len;
         const unsigned char *binder;
 
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, binders_end, 1 );
         binder_len = *p++;
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binder_len );
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, binders_end, binder_len );
         binder = p;
         p += binder_len;
 
@@ -326,10 +325,10 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
             MBEDTLS_SSL_DEBUG_RET( 1,
                 "ssl_tls13_offered_psks_check_binder_match" , binder_matched );
             MBEDTLS_SSL_PEND_FATAL_ALERT(
-                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
+                MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR,
                 MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
             ret = binder_matched;
-            goto exit_failue;
+            goto exit_failure;
         }
     }
 
@@ -341,7 +340,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
             MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
             MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
         ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
-        goto exit_failue;
+        goto exit_failure;
     }
 
     if( p != binders_end )
@@ -350,7 +349,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
                                       MBEDTLS_ERR_SSL_DECODE_ERROR );
         ret = MBEDTLS_ERR_SSL_DECODE_ERROR;
-        goto exit_failue;
+        goto exit_failure;
     }
 
     /* Update the handshake transcript with the binder list. */
@@ -359,7 +358,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
                                      (size_t)( p - identities_end ) );
     ret = 0;
 
-exit_failue:
+exit_failure:
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
     mbedtls_free( (void *)psk );
 #endif

From 1c9247cff4292894af7c7ab931f7c1b82bc59b8d Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Thu, 21 Jul 2022 12:37:39 +0800
Subject: [PATCH 11/19] TLS 1.3: Add pre_share_key last ext check

From RFC, pre_share_key must be the last one.
Add check for it. And with/without psk, it should
be check

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 89a718b4d4..d095fcae62 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1037,6 +1037,23 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
         size_t extension_data_len;
         const unsigned char *extension_data_end;
 
+        /* RFC 8446, page 57
+         *
+         * The "pre_shared_key" extension MUST be the last extension in the
+         * ClientHello (this facilitates implementation as described below).
+         * Servers MUST check that it is the last extension and otherwise fail
+         * the handshake with an "illegal_parameter" alert.
+         */
+        if( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY )
+        {
+            MBEDTLS_SSL_DEBUG_MSG(
+                3, ( "pre_shared_key is not last extension." ) );
+            MBEDTLS_SSL_PEND_FATAL_ALERT(
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+            return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        }
+
         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 );
@@ -1146,19 +1163,18 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
                 break;
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
-#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
             case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
                 MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
                 /* Delay processing of the PSK identity once we have
                  * found out which algorithms to use. We keep a pointer
                  * to the buffer and the size for later processing.
                  */
                 pre_shared_key_ext_start = p;
                 pre_shared_key_ext_end = extension_data_end;
-
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
                 ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
                 break;
-#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 #if defined(MBEDTLS_SSL_ALPN)
             case MBEDTLS_TLS_EXT_ALPN:
@@ -1231,13 +1247,6 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
                                    ret );
             return( ret );
         }
-        /* If pre_shared_key is not last extension */
-        if( p - pre_shared_key_ext_end )
-        {
-            ssl->handshake->update_checksum( ssl,
-                                             pre_shared_key_ext_end,
-                                             p - pre_shared_key_ext_end );
-        }
     }
     else
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */

From 96a2e368dcc28056f240d88e5bc2195973ebf8a8 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Thu, 21 Jul 2022 15:11:34 +0800
Subject: [PATCH 12/19] TLS 1.3: Add pre-shared-key multiple psk parser

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_misc.h         |   1 +
 library/ssl_tls13_server.c | 271 ++++++++++++++++++-------------------
 tests/ssl-opt.sh           |  26 ++--
 3 files changed, 148 insertions(+), 150 deletions(-)

diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 381f0c4bfa..ecc2a62afe 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -680,6 +680,7 @@ struct mbedtls_ssl_handshake_params
     unsigned char *psk;                 /*!<  PSK from the callback         */
     size_t psk_len;                     /*!<  Length of PSK from callback   */
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
+    uint16_t    selected_identity;
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 #if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index d095fcae62..d67f4534a7 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -119,6 +119,7 @@ static int ssl_tls13_offered_psks_check_identity_match(
         return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
     }
 
+    MBEDTLS_SSL_DEBUG_BUF( 5, "identity", identity, identity_len );
     /* Check identity with pre-configured psk */
     if( identity_len == ssl->conf->psk_identity_len &&
         mbedtls_ct_memcmp( ssl->conf->psk_identity,
@@ -132,20 +133,59 @@ static int ssl_tls13_offered_psks_check_identity_match(
 }
 
 MBEDTLS_CHECK_RETURN_CRITICAL
-static int ssl_tls13_offered_psks_check_binder_match(
-               mbedtls_ssl_context *ssl,
-               const unsigned char *binder,
-               uint16_t binder_len,
-               const unsigned char *psk,
-               size_t psk_len )
+static int ssl_tls13_get_psk( mbedtls_ssl_context *ssl,
+                              const unsigned char **psk,
+                              size_t *psk_len )
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_status_t status;
+
+    *psk_len = 0;
+    *psk = NULL;
+
+    status = psa_get_key_attributes( ssl->handshake->psk_opaque, &key_attributes );
+    if( status != PSA_SUCCESS)
+    {
+        return( psa_ssl_status_to_mbedtls( status ) );
+    }
+
+    *psk_len = PSA_BITS_TO_BYTES(psa_get_key_bits( &key_attributes ) );
+    *psk = mbedtls_calloc( 1, *psk_len );
+    if( *psk == NULL )
+    {
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    status = psa_export_key( ssl->handshake->psk_opaque,
+                             (uint8_t *)*psk, *psk_len, psk_len );
+    if( status != PSA_SUCCESS)
+    {
+        mbedtls_free( (void *)*psk );
+        return( psa_ssl_status_to_mbedtls( status ) );
+    }
+#else
+    *psk = ssl->handshake->psk;
+    *psk_len = ssl->handshake->psk_len;
+#endif /* !MBEDTLS_USE_PSA_CRYPTO */
+    return( 0 );
+}
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl,
+                                                      const unsigned char *binder,
+                                                      uint16_t binder_len )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     int psk_type;
+
     mbedtls_md_type_t md_alg =
         binder_len == 32 ? MBEDTLS_MD_SHA256 : MBEDTLS_MD_SHA384 ;
     psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg );
     unsigned char transcript[PSA_HASH_MAX_SIZE];
     size_t transcript_len;
+    const unsigned char *psk;
+    size_t psk_len;
     unsigned char server_computed_binder[PSA_HASH_MAX_SIZE];
 
     psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
@@ -157,11 +197,17 @@ static int ssl_tls13_offered_psks_check_binder_match(
     if( ret != 0 )
         return( ret );
 
+    ret = ssl_tls13_get_psk( ssl, &psk, &psk_len );
+    if( ret != 0 )
+        return( ret );
+
     ret = mbedtls_ssl_tls13_create_psk_binder( ssl, psa_md_alg,
                                                psk, psk_len, psk_type,
                                                transcript,
                                                server_computed_binder );
-    /* We do not check for multiple binders */
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_free( (void*)psk );
+#endif
     if( ret != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "PSK binder calculation failed." ) );
@@ -181,6 +227,7 @@ static int ssl_tls13_offered_psks_check_binder_match(
                               sizeof( server_computed_binder ) );
     return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH );
 }
+
 /* Parser for pre_shared_key extension in client hello
  *    struct {
  *        opaque identity<1..2^16-1>;
@@ -206,63 +253,89 @@ static int ssl_tls13_parse_pre_shared_key_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;
+    const unsigned char *next_identity = buf;
     uint16_t identities_len;
     const unsigned char *identities_end;
-    uint32_t identity_matched = SSL_TLS1_3_OFFERED_PSK_NOT_MATCH;
+    const unsigned char *next_binder;
     uint16_t binders_len;
     const unsigned char *binders_end;
-    unsigned char *psk = NULL;
-    size_t psk_len = 0;
-    int binder_matched = 0;
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
-    psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_status_t status;
-#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    int matched_identity = -1;
+    int identity_id = -1;
 
     MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extesion", buf, end - buf );
 
-    /* identities   >= 7 bytes */
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 7 );
+    /* identities_len       2 bytes
+     * identities_data   >= 7 bytes
+     */
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, end, 7 + 2 );
+    identities_len = MBEDTLS_GET_UINT16_BE( next_identity, 0 );
+    next_identity += 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, end, identities_len );
+    identities_end = next_identity + identities_len;
 
-    identities_len = MBEDTLS_GET_UINT16_BE( p, 0 );
-    p += 2;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, identities_len );
-    identities_end = p + identities_len;
+    /* binders_len     2  bytes
+     * binders      >= 33 bytes
+     */
+    next_binder = identities_end;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, end, 33 );
+    binders_len = MBEDTLS_GET_UINT16_BE( next_binder, 0 );
+    next_binder += 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, end, binders_len );
+    binders_end = next_binder + binders_len;
 
-    while( p < identities_end )
+    ssl->handshake->update_checksum( ssl, buf, identities_end - buf );
+
+    while( next_identity < identities_end && next_binder < binders_end )
     {
-        uint16_t identity_len;
         const unsigned char *identity;
+        uint16_t identity_len;
+        const unsigned char *binder;
+        uint16_t binder_len;
+        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, identities_end, 2 );
-        identity_len = MBEDTLS_GET_UINT16_BE( p, 0 );
-        p += 2;
-        identity = p;
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( identity,
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, identities_end, 2 );
+        identity_len = MBEDTLS_GET_UINT16_BE( next_identity, 0 );
+        next_identity += 2;
+        identity = next_identity;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity,
                                       identities_end,
                                       identity_len + 4  );
-        p += identity_len + 4;
+        next_identity += identity_len + 4;
 
-        if( identity_matched == SSL_TLS1_3_OFFERED_PSK_MATCH )
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, binders_end, 2 );
+
+        binder_len = *next_binder++;
+        binder = next_binder;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, binders_end, binder_len );
+        next_binder += binder_len;
+
+        identity_id++;
+        if( matched_identity != -1 )
             continue;
 
-        MBEDTLS_SSL_DEBUG_BUF( 3, "received psk identity",
-                               identity, identity_len );
-        identity_matched = ssl_tls13_offered_psks_check_identity_match(
-                              ssl, identity, identity_len );
+        ret = ssl_tls13_offered_psks_check_identity_match(
+                                            ssl, identity, identity_len );
+        if( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH == ret )
+            continue;
+
+        ret = ssl_tls13_offered_psks_check_binder_match(
+                                            ssl, binder, binder_len );
+        if( ret < 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1,
+                "ssl_tls13_offered_psks_check_binder_match" , ret );
+            MBEDTLS_SSL_PEND_FATAL_ALERT(
+                MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR,
+                MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+            return( ret );
+        }
+        if( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH == ret )
+            continue;
+
+        matched_identity = identity_id;
     }
 
-    if( identity_matched != SSL_TLS1_3_OFFERED_PSK_MATCH )
-    {
-        MBEDTLS_SSL_PEND_FATAL_ALERT(
-            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY,
-            MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
-        return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
-    }
-
-    if( p != identities_end )
+    if( next_identity != identities_end || next_binder != binders_end )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
         MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
@@ -270,99 +343,23 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
     }
 
-    ssl->handshake->update_checksum( ssl, buf, p - buf );
-
-    /* binders      >= 33 bytes */
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 33 );
-    binders_len = MBEDTLS_GET_UINT16_BE( p, 0 );
-    p += 2;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binders_len );
-    binders_end = p + binders_len;
-
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
-    status = psa_get_key_attributes( ssl->handshake->psk_opaque,
-                                         &key_attributes );
-    if( status != PSA_SUCCESS)
+    if( matched_identity == -1 )
     {
-        return( psa_ssl_status_to_mbedtls( status ) );
-    }
-
-    psk_len = PSA_BITS_TO_BYTES(psa_get_key_bits( &key_attributes ) );
-    psk = mbedtls_calloc( 1, psk_len );
-    if( psk == NULL )
-    {
-        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
-    }
-    status = psa_export_key(ssl->handshake->psk_opaque, psk, psk_len, &psk_len );
-    if( status != PSA_SUCCESS)
-    {
-        ret = psa_ssl_status_to_mbedtls( status );
-        goto exit_failure;
-    }
-#else
-    psk = ssl->handshake->psk;
-    psk_len = ssl->handshake->psk_len;
-#endif /* !MBEDTLS_USE_PSA_CRYPTO */
-
-    while( p < binders_end )
-    {
-        uint8_t binder_len;
-        const unsigned char *binder;
-
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, binders_end, 1 );
-        binder_len = *p++;
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( p, binders_end, binder_len );
-        binder = p;
-        p += binder_len;
-
-        if( binder_matched == SSL_TLS1_3_OFFERED_PSK_MATCH)
-            continue;
-
-        binder_matched = ssl_tls13_offered_psks_check_binder_match(
-                              ssl, binder, binder_len, psk, psk_len );
-        if( binder_matched < 0 )
-        {
-            MBEDTLS_SSL_DEBUG_RET( 1,
-                "ssl_tls13_offered_psks_check_binder_match" , binder_matched );
-            MBEDTLS_SSL_PEND_FATAL_ALERT(
-                MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR,
-                MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
-            ret = binder_matched;
-            goto exit_failure;
-        }
-    }
-
-    if( binder_matched != SSL_TLS1_3_OFFERED_PSK_MATCH )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 1,
-            ( "Received psk binder does not match computed psk binder." ) );
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "No matched pre shared key found" ) );
         MBEDTLS_SSL_PEND_FATAL_ALERT(
-            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE,
-            MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
-        ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
-        goto exit_failure;
+            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY,
+            MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
+        return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
     }
 
-    if( p != binders_end )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
-        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
-                                      MBEDTLS_ERR_SSL_DECODE_ERROR );
-        ret = MBEDTLS_ERR_SSL_DECODE_ERROR;
-        goto exit_failure;
-    }
+    ssl->handshake->selected_identity = (uint16_t)matched_identity;
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "Pre shared key found" ) );
 
     /* Update the handshake transcript with the binder list. */
     ssl->handshake->update_checksum( ssl,
                                      identities_end,
-                                     (size_t)( p - identities_end ) );
-    ret = 0;
-
-exit_failure:
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
-    mbedtls_free( (void *)psk );
-#endif
-    return( ret );
+                                     (size_t)( binders_end - identities_end ) );
+    return( 0 );
 }
 
 /*
@@ -380,7 +377,6 @@ static int ssl_tls13_write_server_pre_shared_key_ext( mbedtls_ssl_context *ssl,
                                                       size_t *olen )
 {
     unsigned char *p = (unsigned char*)buf;
-    size_t selected_identity;
 
     *olen = 0;
 
@@ -401,15 +397,12 @@ static int ssl_tls13_write_server_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0 );
     MBEDTLS_PUT_UINT16_BE( 2, p, 2 );
 
-    /* NOTE: This will need to be adjusted once we support multiple PSKs
-     *       being offered by the client. */
-    selected_identity = 0;
-    MBEDTLS_PUT_UINT16_BE( selected_identity, p, 4 );
+    MBEDTLS_PUT_UINT16_BE( ssl->handshake->selected_identity, p, 4 );
 
     *olen = 6;
 
-    MBEDTLS_SSL_DEBUG_MSG( 4, ( "sent selected_identity: %" MBEDTLS_PRINTF_SIZET,
-                                selected_identity ) );
+    MBEDTLS_SSL_DEBUG_MSG( 4, ( "sent selected_identity: %u",
+                                ssl->handshake->selected_identity ) );
 
     return( 0 );
 }
@@ -1709,9 +1702,7 @@ static int ssl_tls13_write_server_hello_body( mbedtls_ssl_context *ssl,
     }
 
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
-    MBEDTLS_SSL_DEBUG_MSG( 2, ( " mbedtls_ssl_tls13_some_psk_enabled %d",
-                                mbedtls_ssl_tls13_some_psk_enabled( ssl ) ) );
-    if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) )
+    if( mbedtls_ssl_tls13_key_exchange_mode_with_psk( ssl ) )
     {
         ret = ssl_tls13_write_server_pre_shared_key_ext( ssl, p, end, &output_len );
         if( ret != 0 )
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 942d705242..24f14e3f54 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -2286,30 +2286,36 @@ run_test    "TLS 1.3: key exchange mode parameter passing: All" \
 requires_openssl_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+requires_config_enabled MBEDTLS_KEY_EXCHANGE_PSK_ENABLED
 requires_config_enabled MBEDTLS_SSL_SRV_C
 requires_config_enabled MBEDTLS_DEBUG_C
-run_test    "TLS 1.3: psk_key_exchange_modes: basic check, O->m" \
-            "$P_SRV force_version=tls13 debug_level=5" \
-            "$O_NEXT_CLI -tls1_3 -psk 6162636465666768696a6b6c6d6e6f70 -allow_no_dhe_kex" \
-            0 \
+run_test    "TLS 1.3: PSK: basic check, O->m" \
+            "$P_SRV force_version=tls13 tls13_kex_modes=psk debug_level=5 psk=6162636465666768696a6b6c6d6e6f70" \
+            "$O_NEXT_CLI -tls1_3 -psk 1234 -psk 6162636465666768696a6b6c6d6e6f70 -allow_no_dhe_kex" \
+            1 \
             -s "found psk key exchange modes extension" \
+            -s "found pre_shared_key extension" \
             -s "Found PSK_EPHEMERAL KEX MODE" \
-            -s "Found PSK KEX MODE"
+            -s "Found PSK KEX MODE" \
+            -s "Pre shared key found"
 
 requires_gnutls_tls1_3
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
 requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+requires_config_enabled MBEDTLS_KEY_EXCHANGE_PSK_ENABLED
 requires_config_enabled MBEDTLS_SSL_SRV_C
 requires_config_enabled MBEDTLS_DEBUG_C
-run_test    "TLS 1.3: psk_key_exchange_modes: basic check, G->m" \
-            "$P_SRV force_version=tls13 debug_level=5" \
-            "$G_NEXT_CLI --priority NORMAL:-VERS-ALL:+VERS-TLS1.3 \
+run_test    "TLS 1.3: PSK: basic check, G->m" \
+            "$P_SRV force_version=tls13 tls13_kex_modes=psk debug_level=5 psk=6162636465666768696a6b6c6d6e6f70" \
+            "$G_NEXT_CLI --priority NORMAL:-VERS-ALL:+KX-ALL:+PSK:+DHE-PSK:+VERS-TLS1.3 \
                          --pskusername Client_identity --pskkey=6162636465666768696a6b6c6d6e6f70 \
                          localhost" \
-            0 \
+            1 \
             -s "found psk key exchange modes extension" \
+            -s "found pre_shared_key extension" \
             -s "Found PSK_EPHEMERAL KEX MODE" \
-            -s "Found PSK KEX MODE"
+            -s "Found PSK KEX MODE" \
+            -s "Pre shared key found"
 
 # Tests for datagram packing
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2

From 77f0148e114877e8a53faf804567d84cc2715353 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Mon, 11 Jul 2022 07:03:24 +0000
Subject: [PATCH 13/19] Add psk/psk_ephemeral key exchange check

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 include/mbedtls/ssl.h      |   2 +
 library/ssl_tls13_server.c | 138 ++++++++++++++++++++++++++++++-------
 2 files changed, 114 insertions(+), 26 deletions(-)

diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index e665ec1b7b..bc09e7a186 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -250,6 +250,8 @@
     ( MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL        |            \
       MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL    ) /*!< All ephemeral TLS 1.3 key exchanges */
 
+#define MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE   ( 0 )
+
 /*
  * Various constants
  */
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index d67f4534a7..bf49af21b4 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -692,24 +692,121 @@ MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange(
         mbedtls_ssl_context *ssl )
 {
-    return( ssl_tls13_client_hello_has_exts( ssl,
-                                             MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
-                                             MBEDTLS_SSL_EXT_KEY_SHARE        |
-                                             MBEDTLS_SSL_EXT_SIG_ALG ) );
+    return( ssl_tls13_client_hello_has_exts(
+                ssl,
+                MBEDTLS_SSL_EXT_SUPPORTED_GROUPS |
+                MBEDTLS_SSL_EXT_KEY_SHARE        |
+                MBEDTLS_SSL_EXT_SIG_ALG ) );
 }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_client_hello_has_exts_for_psk_key_exchange(
+               mbedtls_ssl_context *ssl )
+{
+    return( ssl_tls13_client_hello_has_exts(
+                ssl,
+                MBEDTLS_SSL_EXT_PRE_SHARED_KEY          |
+                MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) );
+}
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange(
+               mbedtls_ssl_context *ssl )
+{
+    return( ssl_tls13_client_hello_has_exts(
+                ssl,
+                MBEDTLS_SSL_EXT_SUPPORTED_GROUPS        |
+                MBEDTLS_SSL_EXT_KEY_SHARE               |
+                MBEDTLS_SSL_EXT_PRE_SHARED_KEY          |
+                MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_check_ephemeral_key_exchange( mbedtls_ssl_context *ssl )
 {
-    if( !mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) )
-        return( 0 );
+    return( mbedtls_ssl_conf_tls13_ephemeral_enabled( ssl ) &&
+            ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( ssl ) );
+}
 
-    if( !ssl_tls13_client_hello_has_exts_for_ephemeral_key_exchange( ssl ) )
-        return( 0 );
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_check_psk_key_exchange( mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    return( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) &&
+            mbedtls_ssl_tls13_psk_enabled( ssl ) &&
+            ssl_tls13_client_hello_has_exts_for_psk_key_exchange( ssl ) );
+#else
+    ((void) ssl);
+    return( 0 );
+#endif
+}
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_check_psk_ephemeral_key_exchange( mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    return( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) &&
+            mbedtls_ssl_tls13_psk_ephemeral_enabled( ssl ) &&
+            ssl_tls13_client_hello_has_exts_for_psk_ephemeral_key_exchange( ssl ) );
+#else
+    ((void) ssl);
+    return( 0 );
+#endif
+}
+
+static int ssl_tls13_determine_key_exchange_mode( mbedtls_ssl_context *ssl )
+{
+    /*
+     * Determine the key exchange algorithm to use.
+     * There are three types of key exchanges supported in TLS 1.3:
+     * - (EC)DH with ECDSA,
+     * - (EC)DH with PSK,
+     * - plain PSK.
+     *
+     * The PSK-based key exchanges may additionally be used with 0-RTT.
+     *
+     * Our built-in order of preference is
+     *  1 ) Plain PSK Mode ( psk )
+     *  2 ) (EC)DHE-PSK Mode ( psk_ephemeral )
+     *  3 ) Certificate Mode ( ephemeral )
+     */
+
+    ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE;
+
+    if( ssl_tls13_check_psk_key_exchange( ssl ) )
+    {
+        ssl->handshake->key_exchange_mode =
+            MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk" ) );
+    }
+    else
+    if( ssl_tls13_check_psk_ephemeral_key_exchange( ssl ) )
+    {
+        ssl->handshake->key_exchange_mode =
+            MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk_ephemeral" ) );
+    }
+    else
+    if( ssl_tls13_check_ephemeral_key_exchange( ssl ) )
+    {
+        ssl->handshake->key_exchange_mode =
+            MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: ephemeral" ) );
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG(
+                1,
+                ( "ClientHello message misses mandatory extensions." ) );
+        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION ,
+                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    return( 0 );
 
-    ssl->handshake->key_exchange_mode =
-        MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL;
-    return( 1 );
 }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C) && \
@@ -1216,6 +1313,9 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
     ssl_tls13_debug_print_client_hello_exts( ssl );
 #endif /* MBEDTLS_DEBUG_C */
 
+    ret = ssl_tls13_determine_key_exchange_mode( ssl );
+    if( ret < 0 )
+        return( ret );
     mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
                                         MBEDTLS_SSL_HS_CLIENT_HELLO,
                                         p - buf );
@@ -1226,8 +1326,7 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
      * - The content up to but excluding the PSK extension, if present.
      */
     /* If we've settled on a PSK-based exchange, parse PSK identity ext */
-    if( mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) &&
-        ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) )
+    if( mbedtls_ssl_tls13_key_exchange_mode_with_psk( ssl ) )
     {
         ssl->handshake->update_checksum( ssl, buf,
                                          pre_shared_key_ext_start - buf );
@@ -1257,19 +1356,6 @@ static int ssl_tls13_postprocess_client_hello( mbedtls_ssl_context* ssl )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
-    /*
-     * Here we only support the ephemeral or (EC)DHE key echange mode
-     */
-    if( !ssl_tls13_check_ephemeral_key_exchange( ssl ) )
-    {
-        MBEDTLS_SSL_DEBUG_MSG(
-                1,
-                ( "ClientHello message misses mandatory extensions." ) );
-        MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_MISSING_EXTENSION ,
-                                      MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
-    }
-
     /*
      * Server certificate selection
      */

From 2f0abc94d86eb2091b7abd100d6ec9ecc7947dfc Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 19:34:48 +0800
Subject: [PATCH 14/19] fix typo/type/format issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index bf49af21b4..bbc8535790 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -106,7 +106,7 @@ MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_offered_psks_check_identity_match(
                mbedtls_ssl_context *ssl,
                const unsigned char *identity,
-               uint16_t identity_len )
+               size_t identity_len )
 {
     /* Check identity with external configured function */
     if( ssl->conf->f_psk != NULL )
@@ -121,7 +121,8 @@ static int ssl_tls13_offered_psks_check_identity_match(
 
     MBEDTLS_SSL_DEBUG_BUF( 5, "identity", identity, identity_len );
     /* Check identity with pre-configured psk */
-    if( identity_len == ssl->conf->psk_identity_len &&
+    if( ssl->conf->psk_identity != NULL &&
+        identity_len == ssl->conf->psk_identity_len &&
         mbedtls_ct_memcmp( ssl->conf->psk_identity,
                             identity, identity_len ) == 0 )
     {
@@ -134,7 +135,7 @@ static int ssl_tls13_offered_psks_check_identity_match(
 
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_get_psk( mbedtls_ssl_context *ssl,
-                              const unsigned char **psk,
+                              unsigned char **psk,
                               size_t *psk_len )
 {
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
@@ -150,7 +151,7 @@ static int ssl_tls13_get_psk( mbedtls_ssl_context *ssl,
         return( psa_ssl_status_to_mbedtls( status ) );
     }
 
-    *psk_len = PSA_BITS_TO_BYTES(psa_get_key_bits( &key_attributes ) );
+    *psk_len = PSA_BITS_TO_BYTES( psa_get_key_bits( &key_attributes ) );
     *psk = mbedtls_calloc( 1, *psk_len );
     if( *psk == NULL )
     {
@@ -174,22 +175,32 @@ static int ssl_tls13_get_psk( mbedtls_ssl_context *ssl,
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl,
                                                       const unsigned char *binder,
-                                                      uint16_t binder_len )
+                                                      size_t binder_len )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     int psk_type;
 
-    mbedtls_md_type_t md_alg =
-        binder_len == 32 ? MBEDTLS_MD_SHA256 : MBEDTLS_MD_SHA384 ;
-    psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg );
+    mbedtls_md_type_t md_alg;
+    psa_algorithm_t psa_md_alg;
     unsigned char transcript[PSA_HASH_MAX_SIZE];
     size_t transcript_len;
-    const unsigned char *psk;
+    unsigned char *psk;
     size_t psk_len;
     unsigned char server_computed_binder[PSA_HASH_MAX_SIZE];
 
     psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
-
+    switch( binder_len )
+    {
+    case 32:
+        md_alg = MBEDTLS_MD_SHA256;
+        break;
+    case 48:
+        md_alg = MBEDTLS_MD_SHA384;
+        break;
+    default:
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+    psa_md_alg = mbedtls_psa_translate_md( md_alg );
     /* Get current state of handshake transcript. */
     ret = mbedtls_ssl_get_handshake_transcript( ssl, md_alg,
                                                 transcript, sizeof( transcript ),
@@ -215,7 +226,7 @@ static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl,
     }
 
     MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( computed ): ",
-                           server_computed_binder, binder_len );
+                           server_computed_binder, transcript_len );
     MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( received ): ", binder, binder_len );
 
     if( mbedtls_ct_memcmp( server_computed_binder, binder, binder_len ) == 0 )
@@ -262,7 +273,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     int matched_identity = -1;
     int identity_id = -1;
 
-    MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extesion", buf, end - buf );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extension", buf, end - buf );
 
     /* identities_len       2 bytes
      * identities_data   >= 7 bytes

From 568ec2502ab02c492c3c5b7a298a3ccb698e033e Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 21:27:34 +0800
Subject: [PATCH 15/19] fix format/name issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls.c          |  4 ++
 library/ssl_tls13_server.c | 81 +++++++++++++++++++-------------------
 2 files changed, 44 insertions(+), 41 deletions(-)

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index cf9583ccb7..292e931355 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1710,8 +1710,12 @@ int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl,
     else
         alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
     psa_set_key_usage_flags( &key_attributes,
                              PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT );
+#else
+    psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
+#endif
     psa_set_key_algorithm( &key_attributes, alg );
     psa_set_key_type( &key_attributes, PSA_KEY_TYPE_DERIVE );
 
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index bbc8535790..c5aacc3df9 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -191,14 +191,14 @@ static int ssl_tls13_offered_psks_check_binder_match( mbedtls_ssl_context *ssl,
     psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
     switch( binder_len )
     {
-    case 32:
-        md_alg = MBEDTLS_MD_SHA256;
-        break;
-    case 48:
-        md_alg = MBEDTLS_MD_SHA384;
-        break;
-    default:
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        case 32:
+            md_alg = MBEDTLS_MD_SHA256;
+            break;
+        case 48:
+            md_alg = MBEDTLS_MD_SHA384;
+            break;
+        default:
+            return( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR );
     }
     psa_md_alg = mbedtls_psa_translate_md( md_alg );
     /* Get current state of handshake transcript. */
@@ -264,11 +264,13 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
                                                const unsigned char *buf,
                                                const unsigned char *end )
 {
-    const unsigned char *next_identity = buf;
-    uint16_t identities_len;
+    const unsigned char *identities = buf;
+    const unsigned char *p_identity_len;
+    size_t identities_len;
     const unsigned char *identities_end;
-    const unsigned char *next_binder;
-    uint16_t binders_len;
+    const unsigned char *binders;
+    const unsigned char *p_binder_len;
+    size_t binders_len;
     const unsigned char *binders_end;
     int matched_identity = -1;
     int identity_id = -1;
@@ -278,47 +280,44 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     /* identities_len       2 bytes
      * identities_data   >= 7 bytes
      */
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, end, 7 + 2 );
-    identities_len = MBEDTLS_GET_UINT16_BE( next_identity, 0 );
-    next_identity += 2;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, end, identities_len );
-    identities_end = next_identity + identities_len;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( identities, end, 7 + 2 );
+    identities_len = MBEDTLS_GET_UINT16_BE( identities, 0 );
+    p_identity_len = identities + 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p_identity_len, end, identities_len );
+    identities_end = p_identity_len + identities_len;
 
     /* binders_len     2  bytes
      * binders      >= 33 bytes
      */
-    next_binder = identities_end;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, end, 33 );
-    binders_len = MBEDTLS_GET_UINT16_BE( next_binder, 0 );
-    next_binder += 2;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, end, binders_len );
-    binders_end = next_binder + binders_len;
+    binders = identities_end;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( binders, end, 33 );
+    binders_len = MBEDTLS_GET_UINT16_BE( binders, 0 );
+    p_binder_len = binders + 2;
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, end, binders_len );
+    binders_end = p_binder_len + binders_len;
 
     ssl->handshake->update_checksum( ssl, buf, identities_end - buf );
 
-    while( next_identity < identities_end && next_binder < binders_end )
+    while( p_identity_len < identities_end && p_binder_len < binders_end )
     {
         const unsigned char *identity;
-        uint16_t identity_len;
+        size_t identity_len;
         const unsigned char *binder;
-        uint16_t binder_len;
+        size_t binder_len;
         int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity, identities_end, 2 );
-        identity_len = MBEDTLS_GET_UINT16_BE( next_identity, 0 );
-        next_identity += 2;
-        identity = next_identity;
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_identity,
-                                      identities_end,
-                                      identity_len + 4  );
-        next_identity += identity_len + 4;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p_identity_len, identities_end, 2 + 1 + 4 );
+        identity_len = MBEDTLS_GET_UINT16_BE( p_identity_len, 0 );
+        identity = p_identity_len + 2;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len + 4 );
+        p_identity_len += identity_len + 6;
 
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, binders_end, 2 );
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, binders_end, 1 + 32 );
+        binder_len = *p_binder_len;
+        binder = p_binder_len + 1;
+        MBEDTLS_SSL_CHK_BUF_READ_PTR( binder, binders_end, binder_len );
+        p_binder_len += binder_len + 1;
 
-        binder_len = *next_binder++;
-        binder = next_binder;
-        MBEDTLS_SSL_CHK_BUF_READ_PTR( next_binder, binders_end, binder_len );
-        next_binder += binder_len;
 
         identity_id++;
         if( matched_identity != -1 )
@@ -331,7 +330,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
 
         ret = ssl_tls13_offered_psks_check_binder_match(
                                             ssl, binder, binder_len );
-        if( ret < 0 )
+        if( ret != SSL_TLS1_3_OFFERED_PSK_MATCH )
         {
             MBEDTLS_SSL_DEBUG_RET( 1,
                 "ssl_tls13_offered_psks_check_binder_match" , ret );
@@ -346,7 +345,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         matched_identity = identity_id;
     }
 
-    if( next_identity != identities_end || next_binder != binders_end )
+    if( p_identity_len != identities_end || p_binder_len != binders_end )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) );
         MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,

From ba9b6e9e5334a40104c03809c56355527ec0c4eb Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 21:35:18 +0800
Subject: [PATCH 16/19] fix unkown identity case

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index c5aacc3df9..28e99d5d6f 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -356,9 +356,6 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     if( matched_identity == -1 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "No matched pre shared key found" ) );
-        MBEDTLS_SSL_PEND_FATAL_ALERT(
-            MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY,
-            MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
         return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY );
     }
 
@@ -1317,15 +1314,11 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
         p += extension_data_len;
     }
 
-
 #if defined(MBEDTLS_DEBUG_C)
     /* List all the extensions we have received */
     ssl_tls13_debug_print_client_hello_exts( ssl );
 #endif /* MBEDTLS_DEBUG_C */
 
-    ret = ssl_tls13_determine_key_exchange_mode( ssl );
-    if( ret < 0 )
-        return( ret );
     mbedtls_ssl_add_hs_hdr_to_checksum( ssl,
                                         MBEDTLS_SSL_HS_CLIENT_HELLO,
                                         p - buf );
@@ -1336,14 +1329,18 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
      * - The content up to but excluding the PSK extension, if present.
      */
     /* If we've settled on a PSK-based exchange, parse PSK identity ext */
-    if( mbedtls_ssl_tls13_key_exchange_mode_with_psk( ssl ) )
+    if( mbedtls_ssl_tls13_some_psk_enabled( ssl ) &&
+        ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) )
     {
         ssl->handshake->update_checksum( ssl, buf,
                                          pre_shared_key_ext_start - buf );
         ret = ssl_tls13_parse_pre_shared_key_ext( ssl,
                                                   pre_shared_key_ext_start,
                                                   pre_shared_key_ext_end );
-        if( ret != 0 )
+        if( ret == MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY)
+        {
+            ssl->handshake->extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
+        }else if( ret != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_pre_shared_key_ext" ),
                                    ret );
@@ -1356,6 +1353,10 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
         ssl->handshake->update_checksum( ssl, buf, p - buf );
     }
 
+    ret = ssl_tls13_determine_key_exchange_mode( ssl );
+    if( ret < 0 )
+        return( ret );
+
     return( hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK );
 }
 

From ce6ed7076aade44e355dbf540c520bf68f661f57 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 21:49:53 +0800
Subject: [PATCH 17/19] Change the order of key_exchange determine

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 28e99d5d6f..10e9bb7b0b 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -775,20 +775,13 @@ static int ssl_tls13_determine_key_exchange_mode( mbedtls_ssl_context *ssl )
      * The PSK-based key exchanges may additionally be used with 0-RTT.
      *
      * Our built-in order of preference is
-     *  1 ) Plain PSK Mode ( psk )
-     *  2 ) (EC)DHE-PSK Mode ( psk_ephemeral )
-     *  3 ) Certificate Mode ( ephemeral )
+     *  1 ) (EC)DHE-PSK Mode ( psk_ephemeral )
+     *  2 ) Certificate Mode ( ephemeral )
+     *  3 ) Plain PSK Mode ( psk )
      */
 
     ssl->handshake->key_exchange_mode = MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_NONE;
 
-    if( ssl_tls13_check_psk_key_exchange( ssl ) )
-    {
-        ssl->handshake->key_exchange_mode =
-            MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
-        MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk" ) );
-    }
-    else
     if( ssl_tls13_check_psk_ephemeral_key_exchange( ssl ) )
     {
         ssl->handshake->key_exchange_mode =
@@ -803,6 +796,13 @@ static int ssl_tls13_determine_key_exchange_mode( mbedtls_ssl_context *ssl )
         MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: ephemeral" ) );
     }
     else
+    if( ssl_tls13_check_psk_key_exchange( ssl ) )
+    {
+        ssl->handshake->key_exchange_mode =
+            MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK;
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "key exchange mode: psk" ) );
+    }
+    else
     {
         MBEDTLS_SSL_DEBUG_MSG(
                 1,

From 6f1db3fc921373ff4e0147b1fc6acf285aecc2e9 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 23:05:59 +0800
Subject: [PATCH 18/19] fix format and potential non-PSK fail issue

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 10e9bb7b0b..74471970ad 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -290,7 +290,7 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
      * binders      >= 33 bytes
      */
     binders = identities_end;
-    MBEDTLS_SSL_CHK_BUF_READ_PTR( binders, end, 33 );
+    MBEDTLS_SSL_CHK_BUF_READ_PTR( binders, end, 33 + 2 );
     binders_len = MBEDTLS_GET_UINT16_BE( binders, 0 );
     p_binder_len = binders + 2;
     MBEDTLS_SSL_CHK_BUF_READ_PTR( p_binder_len, end, binders_len );
@@ -353,6 +353,10 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
     }
 
+    /* Update the handshake transcript with the binder list. */
+    ssl->handshake->update_checksum( ssl,
+                                     identities_end,
+                                     (size_t)( binders_end - identities_end ) );
     if( matched_identity == -1 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "No matched pre shared key found" ) );
@@ -362,10 +366,6 @@ static int ssl_tls13_parse_pre_shared_key_ext( mbedtls_ssl_context *ssl,
     ssl->handshake->selected_identity = (uint16_t)matched_identity;
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "Pre shared key found" ) );
 
-    /* Update the handshake transcript with the binder list. */
-    ssl->handshake->update_checksum( ssl,
-                                     identities_end,
-                                     (size_t)( binders_end - identities_end ) );
     return( 0 );
 }
 
@@ -1340,7 +1340,8 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
         if( ret == MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY)
         {
             ssl->handshake->extensions_present &= ~MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
-        }else if( ret != 0 )
+        }
+        else if( ret != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_pre_shared_key_ext" ),
                                    ret );

From 13ab81d5ac5f2c69b05b18cca6515cb253826841 Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Fri, 22 Jul 2022 23:17:11 +0800
Subject: [PATCH 19/19] Add handshake failure in pre_shared_key withou
 psk_kex_modes

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/ssl_tls13_server.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 74471970ad..dcefbceb9e 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1262,6 +1262,14 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl,
 
             case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
                 MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
+                if( ( ssl->handshake->extensions_present &
+                      MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES ) == 0 )
+                {
+                    MBEDTLS_SSL_PEND_FATAL_ALERT(
+                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+                        MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+                    return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+                }
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
                 /* Delay processing of the PSK identity once we have
                  * found out which algorithms to use. We keep a pointer