From 31ed2a2bbb5cd9e2654a7683c3872243471a8556 Mon Sep 17 00:00:00 2001
From: Marco Oliverio <marco@wolfssl.com>
Date: Wed, 12 Apr 2023 12:14:51 +0000
Subject: [PATCH 1/2] dtls13: support Authentication and Integrity-Only Cipher
 Suites

See RFC 9150. To enable the feature use HAVE_NULL_CIPHER compilation flag.
---
 src/dtls13.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/dtls13.c b/src/dtls13.c
index 6149031f5..2e0f68ad6 100644
--- a/src/dtls13.c
+++ b/src/dtls13.c
@@ -301,6 +301,12 @@ static int Dtls13EncryptDecryptRecordNumber(WOLFSSL* ssl, byte* seq,
     byte mask[DTLS13_RN_MASK_SIZE];
     int ret;
 
+#ifdef HAVE_NULL_CIPHER
+    /* Do not encrypt record numbers with null cipher. See RFC 9150 Sec 9 */
+    if (ssl->specs.bulk_cipher_algorithm == wolfssl_cipher_null)
+        return 0;
+#endif /*HAVE_NULL_CIPHER */
+
     ret = Dtls13GetRnMask(ssl, ciphertext, mask, dir);
     if (ret != 0)
         return ret;
@@ -2266,6 +2272,15 @@ int Dtls13SetRecordNumberKeys(WOLFSSL* ssl, enum encrypt_side side)
     }
 #endif /* HAVE_CHACHA */
 
+#ifdef HAVE_NULL_CIPHER
+    if (ssl->specs.bulk_cipher_algorithm == wolfssl_cipher_null) {
+#ifdef WOLFSSL_DEBUG_TLS
+        WOLFSSL_MSG("Skipping Record Number key provisioning with null cipher");
+#endif /* WOLFSSL_DEBUG_TLS */
+        return 0;
+    }
+#endif /* HAVE_NULL_CIPHER */
+
     return NOT_COMPILED_IN;
 }
 

From 35185e1a594e97c517c6872131a7cf3d345898e1 Mon Sep 17 00:00:00 2001
From: Marco Oliverio <marco@wolfssl.com>
Date: Thu, 13 Apr 2023 10:00:09 +0000
Subject: [PATCH 2/2] tests: add dtls13 null cipher test

---
 tests/api.c            | 69 ++++++++++++++++++++++++++++++++++++++++++
 tests/test-dtls13.conf | 20 ++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/tests/api.c b/tests/api.c
index d9958a5a3..450951912 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -65849,6 +65849,74 @@ static int test_dtls13_bad_epoch_ch(void)
 #endif
 
 
+#if defined(HAVE_NULL_CIPHER) && defined(HAVE_IO_TESTS_DEPENDENCIES) && \
+    defined(WOLFSSL_DTLS13)
+static byte* test_find_string(const char *string,
+    byte *buf, int buf_size)
+{
+    int string_size, i;
+
+    string_size = XSTRLEN(string);
+    for (i = 0; i < buf_size - string_size - 1; i++) {
+        if (XSTRCMP((char*)&buf[i], string) == 0)
+            return &buf[i];
+    }
+    return NULL;
+}
+
+static int test_wolfSSL_dtls13_null_cipher(void)
+{
+    WOLFSSL_CTX *ctx_c = NULL, *ctx_s = NULL;
+    WOLFSSL *ssl_c = NULL, *ssl_s = NULL;
+    struct test_memio_ctx test_ctx;
+    const char *test_str = "test";
+    int ret, test_str_size;
+    byte buf[255], *ptr;
+
+    XMEMSET(&test_ctx, 0, sizeof(test_ctx));
+    test_ctx.c_ciphers = test_ctx.s_ciphers = "TLS13-SHA256-SHA256";
+    ret = test_memio_setup(&test_ctx, &ctx_c, &ctx_s, &ssl_c, &ssl_s,
+        wolfDTLSv1_3_client_method, wolfDTLSv1_3_server_method);
+    if (ret != 0)
+        return TEST_FAIL;
+    ret = test_memio_do_handshake(ssl_c, ssl_s, 10, NULL);
+    if (ret != 0)
+        return TEST_FAIL;
+    test_str_size = XSTRLEN("test") + 1;
+    ret = wolfSSL_write(ssl_c, test_str, test_str_size);
+    if (ret != test_str_size)
+        return TEST_FAIL;
+    ret = wolfSSL_read(ssl_s, buf, sizeof(buf));
+    if (ret != test_str_size || XSTRCMP((char*)buf, test_str) != 0)
+        return TEST_FAIL;
+
+    ret = wolfSSL_write(ssl_c, test_str, test_str_size);
+    if (ret != test_str_size)
+        return TEST_FAIL;
+
+    /* check that the packet was sent cleartext */
+    ptr = test_find_string(test_str, test_ctx.s_buff, test_ctx.s_len);
+    if (ptr == NULL)
+        return TEST_FAIL;
+    /* modify the message */
+    *ptr = 'H';
+    /* bad messages should be ignored in DTLS */
+    ret = wolfSSL_read(ssl_s, buf, sizeof(buf));
+    if (ret != -1 || ssl_s->error != WANT_READ)
+        return TEST_FAIL;
+
+    wolfSSL_free(ssl_c);
+    wolfSSL_free(ssl_s);
+    wolfSSL_CTX_free(ctx_c);
+    wolfSSL_CTX_free(ctx_s);
+    return TEST_SUCCESS;
+}
+#else
+static int test_wolfSSL_dtls13_null_cipher(void)
+{
+    return TEST_SKIPPED;
+}
+#endif
 /*----------------------------------------------------------------------------*
  | Main
  *----------------------------------------------------------------------------*/
@@ -66886,6 +66954,7 @@ TEST_CASE testCases[] = {
     TEST_DECL(test_harden_no_secure_renegotiation),
     TEST_DECL(test_override_alt_cert_chain),
     TEST_DECL(test_dtls13_bad_epoch_ch),
+    TEST_DECL(test_wolfSSL_dtls13_null_cipher),
     /* If at some point a stub get implemented this test should fail indicating
      * a need to implement a new test case
      */
diff --git a/tests/test-dtls13.conf b/tests/test-dtls13.conf
index 0186b9a7f..57724e68c 100644
--- a/tests/test-dtls13.conf
+++ b/tests/test-dtls13.conf
@@ -270,3 +270,23 @@
 -u
 -v 4
 -l TLS_AES_128_GCM_SHA256
+
+# server DTLSv1.3 Integrity-only SHA256
+-u
+-v 4
+-l TLS13-SHA256-SHA256
+
+# client DTLSv1.3 Integrity-only SHA256
+-u
+-v 4
+-l TLS13-SHA256-SHA256
+
+# server DTSv1.3 Integrity-only SHA384
+-u
+-v 4
+-l TLS13-SHA384-SHA384
+
+# client DTLSv1.3 Integrity-only SHA384
+-u
+-v 4
+-l TLS13-SHA384-SHA384