diff --git a/ChangeLog b/ChangeLog
index 8d031ad87..3c41c10c1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,22 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 = mbed TLS 2.1.11 branch released xxxx-xx-xx
 
+Default behavior changes
+   * The truncated HMAC extension now conforms to RFC 6066. This means
+     that when both sides of a TLS connection negotiate the truncated
+     HMAC extension, Mbed TLS can now interoperate with other
+     compliant implementations, but this breaks interoperability with
+     prior versions of Mbed TLS. To restore the old behavior, enable
+     the (deprecated) option MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT in
+     config.h. Found by Andreas Walz (ivESK, Offenburg University of
+     Applied Sciences).
+
+Security
+   * Fix implementation of the truncated HMAC extension. The previous
+     implementation allowed an offline 2^80 brute force attack on the
+     HMAC key of a single, uninterrupted connection (with no
+     resumption of the session).
+
 Bugfix
    * Fix assembly sequences in bn_mul.h and aesni.c to avoid segmentation
      faults and errors when building for the 64-bit ILP32 ABI. Found and fixed
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 8dadbe1c5..33ea22a77 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -77,6 +77,10 @@
 #error "MBEDTLS_DHM_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT) && !defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+#error "MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_ECDH_C) && !defined(MBEDTLS_ECP_C)
 #error "MBEDTLS_ECDH_C defined, but not all prerequisites"
 #endif
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 00589dd07..0444eb12a 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1198,6 +1198,27 @@
  */
 #define MBEDTLS_SSL_TRUNCATED_HMAC
 
+/**
+ * \def MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT
+ *
+ * Fallback to old (pre-2.1.10), non-conforming implementation of the truncated
+ * HMAC extension which also truncates the HMAC key. Note that this option is
+ * only meant for a transitory upgrade period and is likely to be removed in
+ * a future version of the library.
+ *
+ * \warning The old implementation is non-compliant and has a security weakness
+ *          (2^80 brute force attack on the HMAC key used for a single,
+ *          uninterrupted connection). This should only be enabled temporarily
+ *          when (1) the use of truncated HMAC is essential in order to save
+ *          bandwidth, and (2) the peer is an Mbed TLS stack that doesn't use
+ *          the fixed implementation yet (pre-2.1.10).
+ *
+ * Uncomment to fallback to old, non-compliant truncated HMAC implementation.
+ *
+ * Requires: MBEDTLS_SSL_TRUNCATED_HMAC
+ */
+//#define MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT
+
 /**
  * \def MBEDTLS_THREADING_ALT
  *
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 7193809b1..5691af7b9 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -491,6 +491,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
     unsigned char *key2;
     unsigned char *mac_enc;
     unsigned char *mac_dec;
+    size_t mac_key_len;
     size_t iv_copy_len;
     const mbedtls_cipher_info_t *cipher_info;
     const mbedtls_md_info_t *md_info;
@@ -682,6 +683,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
         cipher_info->mode == MBEDTLS_MODE_CCM )
     {
         transform->maclen = 0;
+        mac_key_len = 0;
 
         transform->ivlen = 12;
         transform->fixed_ivlen = 4;
@@ -702,7 +704,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
         }
 
         /* Get MAC length */
-        transform->maclen = mbedtls_md_get_size( md_info );
+        mac_key_len = mbedtls_md_get_size( md_info );
+        transform->maclen = mac_key_len;
 
 #if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
         /*
@@ -711,7 +714,15 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
          * so we only need to adjust the length here.
          */
         if( session->trunc_hmac == MBEDTLS_SSL_TRUNC_HMAC_ENABLED )
+        {
             transform->maclen = MBEDTLS_SSL_TRUNCATED_HMAC_LEN;
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT)
+            /* Fall back to old, non-compliant version of the truncated
+             * HMAC implementation which also truncates the key (pre 2.1.10) */
+            mac_key_len = transform->maclen;
+#endif
+        }
 #endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
 
         /* IV length */
@@ -773,11 +784,11 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #if defined(MBEDTLS_SSL_CLI_C)
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
     {
-        key1 = keyblk + transform->maclen * 2;
-        key2 = keyblk + transform->maclen * 2 + transform->keylen;
+        key1 = keyblk + mac_key_len * 2;
+        key2 = keyblk + mac_key_len * 2 + transform->keylen;
 
         mac_enc = keyblk;
-        mac_dec = keyblk + transform->maclen;
+        mac_dec = keyblk + mac_key_len;
 
         /*
          * This is not used in TLS v1.1.
@@ -793,10 +804,10 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #if defined(MBEDTLS_SSL_SRV_C)
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
     {
-        key1 = keyblk + transform->maclen * 2 + transform->keylen;
-        key2 = keyblk + transform->maclen * 2;
+        key1 = keyblk + mac_key_len * 2 + transform->keylen;
+        key2 = keyblk + mac_key_len * 2;
 
-        mac_enc = keyblk + transform->maclen;
+        mac_enc = keyblk + mac_key_len;
         mac_dec = keyblk;
 
         /*
@@ -818,14 +829,14 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #if defined(MBEDTLS_SSL_PROTO_SSL3)
     if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
     {
-        if( transform->maclen > sizeof transform->mac_enc )
+        if( mac_key_len > sizeof transform->mac_enc )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
             return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
         }
 
-        memcpy( transform->mac_enc, mac_enc, transform->maclen );
-        memcpy( transform->mac_dec, mac_dec, transform->maclen );
+        memcpy( transform->mac_enc, mac_enc, mac_key_len );
+        memcpy( transform->mac_dec, mac_dec, mac_key_len );
     }
     else
 #endif /* MBEDTLS_SSL_PROTO_SSL3 */
@@ -833,8 +844,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
     defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
     {
-        mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, transform->maclen );
-        mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, transform->maclen );
+        mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
+        mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
     }
     else
 #endif
@@ -854,7 +865,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                         transform->iv_enc, transform->iv_dec,
                                         iv_copy_len,
                                         mac_enc, mac_dec,
-                                        transform->maclen ) ) != 0 )
+                                        mac_key_len ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_init", ret );
             return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
diff --git a/library/version_features.c b/library/version_features.c
index f9d99af69..b96238ff0 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -381,6 +381,9 @@ static const char *features[] = {
 #if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
     "MBEDTLS_SSL_TRUNCATED_HMAC",
 #endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT)
+    "MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT",
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT */
 #if defined(MBEDTLS_THREADING_ALT)
     "MBEDTLS_THREADING_ALT",
 #endif /* MBEDTLS_THREADING_ALT */
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index c87975cb0..705e5eacb 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -713,34 +713,89 @@ run_test    "Truncated HMAC: client default, server default" \
             -s "dumping 'expected mac' (20 bytes)" \
             -S "dumping 'expected mac' (10 bytes)"
 
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
 run_test    "Truncated HMAC: client disabled, server default" \
             "$P_SRV debug_level=4" \
-            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA \
-             trunc_hmac=0" \
+            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=0" \
             0 \
             -s "dumping 'expected mac' (20 bytes)" \
             -S "dumping 'expected mac' (10 bytes)"
 
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
 run_test    "Truncated HMAC: client enabled, server default" \
             "$P_SRV debug_level=4" \
-            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA \
-             trunc_hmac=1" \
+            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
             0 \
             -s "dumping 'expected mac' (20 bytes)" \
             -S "dumping 'expected mac' (10 bytes)"
 
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
 run_test    "Truncated HMAC: client enabled, server disabled" \
             "$P_SRV debug_level=4 trunc_hmac=0" \
-            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA \
-             trunc_hmac=1" \
+            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
             0 \
             -s "dumping 'expected mac' (20 bytes)" \
             -S "dumping 'expected mac' (10 bytes)"
 
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC: client disabled, server enabled" \
+            "$P_SRV debug_level=4 trunc_hmac=1" \
+            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=0" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
 run_test    "Truncated HMAC: client enabled, server enabled" \
             "$P_SRV debug_level=4 trunc_hmac=1" \
-            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA \
-             trunc_hmac=1" \
+            "$P_CLI force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
+            0 \
+            -S "dumping 'expected mac' (20 bytes)" \
+            -s "dumping 'expected mac' (10 bytes)"
+
+run_test    "Truncated HMAC, DTLS: client default, server default" \
+            "$P_SRV dtls=1 debug_level=4" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC, DTLS: client disabled, server default" \
+            "$P_SRV dtls=1 debug_level=4" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=0" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC, DTLS: client enabled, server default" \
+            "$P_SRV dtls=1 debug_level=4" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC, DTLS: client enabled, server disabled" \
+            "$P_SRV dtls=1 debug_level=4 trunc_hmac=0" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC, DTLS: client disabled, server enabled" \
+            "$P_SRV dtls=1 debug_level=4 trunc_hmac=1" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=0" \
+            0 \
+            -s "dumping 'expected mac' (20 bytes)" \
+            -S "dumping 'expected mac' (10 bytes)"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Truncated HMAC, DTLS: client enabled, server enabled" \
+            "$P_SRV dtls=1 debug_level=4 trunc_hmac=1" \
+            "$P_CLI dtls=1 force_ciphersuite=TLS-RSA-WITH-AES-128-CBC-SHA trunc_hmac=1" \
             0 \
             -S "dumping 'expected mac' (20 bytes)" \
             -s "dumping 'expected mac' (10 bytes)"
@@ -3037,26 +3092,56 @@ run_test    "Small packet TLS 1.0 BlockCipher" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.0 BlockCipher without EtM" \
+run_test    "Small packet TLS 1.0 BlockCipher, without EtM" \
             "$P_SRV" \
             "$P_CLI request_size=1 force_version=tls1 etm=0 \
              force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.0 BlockCipher truncated MAC" \
-            "$P_SRV" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.0 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
             "$P_CLI request_size=1 force_version=tls1 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.0 StreamCipher truncated MAC" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.0 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1 etm=0" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+run_test    "Small packet TLS 1.0 StreamCipher" \
             "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=1 force_version=tls1 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+run_test    "Small packet TLS 1.0 StreamCipher, without EtM" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+            "$P_CLI request_size=1 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.0 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.0 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
+             trunc_hmac=1 etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3067,10 +3152,26 @@ run_test    "Small packet TLS 1.1 BlockCipher" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.1 BlockCipher without EtM" \
+run_test    "Small packet TLS 1.1 BlockCipher, without EtM" \
             "$P_SRV" \
-            "$P_CLI request_size=1 force_version=tls1_1 etm=0 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            "$P_CLI request_size=1 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA etm=0" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.1 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.1 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1 etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3081,19 +3182,26 @@ run_test    "Small packet TLS 1.1 StreamCipher" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.1 BlockCipher truncated MAC" \
-            "$P_SRV" \
+run_test    "Small packet TLS 1.1 StreamCipher, without EtM" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=1 force_version=tls1_1 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.1 StreamCipher truncated MAC" \
-            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.1 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
             "$P_CLI request_size=1 force_version=tls1_1 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.1 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1 etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3104,10 +3212,10 @@ run_test    "Small packet TLS 1.2 BlockCipher" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.2 BlockCipher without EtM" \
+run_test    "Small packet TLS 1.2 BlockCipher, without EtM" \
             "$P_SRV" \
-            "$P_CLI request_size=1 force_version=tls1_2 etm=0 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            "$P_CLI request_size=1 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3118,11 +3226,19 @@ run_test    "Small packet TLS 1.2 BlockCipher larger MAC" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.2 BlockCipher truncated MAC" \
-            "$P_SRV" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.2 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
             "$P_CLI request_size=1 force_version=tls1_2 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.2 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1 etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3133,11 +3249,26 @@ run_test    "Small packet TLS 1.2 StreamCipher" \
             0 \
             -s "Read from client: 1 bytes read"
 
-run_test    "Small packet TLS 1.2 StreamCipher truncated MAC" \
+run_test    "Small packet TLS 1.2 StreamCipher, without EtM" \
             "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=1 force_version=tls1_2 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.2 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet TLS 1.2 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=1 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1 etm=0" \
             0 \
             -s "Read from client: 1 bytes read"
 
@@ -3155,6 +3286,76 @@ run_test    "Small packet TLS 1.2 AEAD shorter tag" \
             0 \
             -s "Read from client: 1 bytes read"
 
+# Tests for small packets in DTLS
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+run_test    "Small packet DTLS 1.0" \
+            "$P_SRV dtls=1 force_version=dtls1" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+run_test    "Small packet DTLS 1.0, without EtM" \
+            "$P_SRV dtls=1 force_version=dtls1 etm=0" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet DTLS 1.0, truncated hmac" \
+            "$P_SRV dtls=1 force_version=dtls1 trunc_hmac=1" \
+            "$P_CLI dtls=1 request_size=1 trunc_hmac=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet DTLS 1.0, without EtM, truncated MAC" \
+            "$P_SRV dtls=1 force_version=dtls1 trunc_hmac=1 etm=0" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1"\
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+run_test    "Small packet DTLS 1.2" \
+            "$P_SRV dtls=1 force_version=dtls1_2" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+run_test    "Small packet DTLS 1.2, without EtM" \
+            "$P_SRV dtls=1 force_version=dtls1_2 etm=0" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet DTLS 1.2, truncated hmac" \
+            "$P_SRV dtls=1 force_version=dtls1_2 trunc_hmac=1" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 1 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Small packet DTLS 1.2, without EtM, truncated MAC" \
+            "$P_SRV dtls=1 force_version=dtls1_2 trunc_hmac=1 etm=0" \
+            "$P_CLI dtls=1 request_size=1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1"\
+            0 \
+            -s "Read from client: 1 bytes read"
+
 # A test for extensions in SSLv3
 
 requires_config_enabled MBEDTLS_SSL_PROTO_SSL3
@@ -3193,20 +3394,57 @@ run_test    "Large packet TLS 1.0 BlockCipher" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.0 BlockCipher truncated MAC" \
+run_test    "Large packet TLS 1.0 BlockCipher, without EtM" \
             "$P_SRV" \
+            "$P_CLI request_size=16384 force_version=tls1 etm=0 recsplit=0 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.0 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
             "$P_CLI request_size=16384 force_version=tls1 recsplit=0 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.0 StreamCipher truncated MAC" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.0 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1 etm=0 recsplit=0 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+run_test    "Large packet TLS 1.0 StreamCipher" \
             "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=16384 force_version=tls1 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+run_test    "Large packet TLS 1.0 StreamCipher, without EtM" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+            "$P_CLI request_size=16384 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.0 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.0 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1 etm=0" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
@@ -3219,6 +3457,29 @@ run_test    "Large packet TLS 1.1 BlockCipher" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
+run_test    "Large packet TLS 1.1 BlockCipher, without EtM" \
+            "$P_SRV" \
+            "$P_CLI request_size=16384 force_version=tls1_1 etm=0 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.1 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.1 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1 etm=0" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
 run_test    "Large packet TLS 1.1 StreamCipher" \
             "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=16384 force_version=tls1_1 \
@@ -3227,20 +3488,27 @@ run_test    "Large packet TLS 1.1 StreamCipher" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.1 BlockCipher truncated MAC" \
-            "$P_SRV" \
+run_test    "Large packet TLS 1.1 StreamCipher, without EtM" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=16384 force_version=tls1_1 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.1 StreamCipher truncated MAC" \
-            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.1 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
             "$P_CLI request_size=16384 force_version=tls1_1 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.1 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_1 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1 etm=0" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
@@ -3253,6 +3521,13 @@ run_test    "Large packet TLS 1.2 BlockCipher" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
+run_test    "Large packet TLS 1.2 BlockCipher, without EtM" \
+            "$P_SRV" \
+            "$P_CLI request_size=16384 force_version=tls1_2 etm=0 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
 run_test    "Large packet TLS 1.2 BlockCipher larger MAC" \
             "$P_SRV" \
             "$P_CLI request_size=16384 force_version=tls1_2 \
@@ -3261,11 +3536,19 @@ run_test    "Large packet TLS 1.2 BlockCipher larger MAC" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.2 BlockCipher truncated MAC" \
-            "$P_SRV" \
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.2 BlockCipher, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
             "$P_CLI request_size=16384 force_version=tls1_2 \
-             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.2 BlockCipher, without EtM, truncated MAC" \
+            "$P_SRV trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-AES-256-CBC-SHA trunc_hmac=1 etm=0" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
@@ -3278,11 +3561,26 @@ run_test    "Large packet TLS 1.2 StreamCipher" \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"
 
-run_test    "Large packet TLS 1.2 StreamCipher truncated MAC" \
+run_test    "Large packet TLS 1.2 StreamCipher, without EtM" \
             "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA" \
             "$P_CLI request_size=16384 force_version=tls1_2 \
-             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA \
-             trunc_hmac=1" \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA etm=0" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.2 StreamCipher, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            0 \
+            -s "Read from client: 16384 bytes read"
+
+requires_config_enabled MBEDTLS_SSL_TRUNCATED_HMAC
+run_test    "Large packet TLS 1.2 StreamCipher, without EtM, truncated MAC" \
+            "$P_SRV arc4=1 force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1" \
+            "$P_CLI request_size=16384 force_version=tls1_2 \
+             force_ciphersuite=TLS-RSA-WITH-RC4-128-SHA trunc_hmac=1 etm=0" \
             0 \
             -c "16384 bytes written in 1 fragments" \
             -s "Read from client: 16384 bytes read"