Add interface for truncated hmac

include/polarssl/ssl.h

@@ -148,6 +148,9 @@
 #define SSL_LEGACY_ALLOW_RENEGOTIATION  1
 #define SSL_LEGACY_BREAK_HANDSHAKE      2
 
+#define SSL_TRUNC_HMAC_DISABLED         0
+#define SSL_TRUNC_HMAC_ENABLED          1
+
 /*
  * Size of the input / output buffer.
  * Note: the RFC defines the default size of SSL / TLS messages. If you
@@ -540,6 +543,7 @@ struct _ssl_context
     int disable_renegotiation;          /*!<  enable/disable renegotiation   */
     int allow_legacy_renegotiation;     /*!<  allow legacy renegotiation     */
     const int *ciphersuite_list[4];     /*!<  allowed ciphersuites / version */
+    int trunc_hmac;                     /*!<  negotiate truncated hmac?      */
 
 #if defined(POLARSSL_DHM_C)
     mpi dhm_P;                          /*!<  prime modulus for DHM   */
@@ -976,6 +980,16 @@ void ssl_set_min_version( ssl_context *ssl, int major, int minor );
  */
 int ssl_set_max_frag_len( ssl_context *ssl, unsigned char mfl_code );
 
+/**
+ * \brief          Activate negotiation of truncated HMAC (Client only)
+ *
+ * \param ssl      SSL context
+ *
+ * \return         O if successful,
+ *                 POLARSSL_ERR_SSL_BAD_INPUT_DATA if used server-side
+ */
+int ssl_set_truncated_hmac( ssl_context *ssl );
+
 /**
  * \brief          Enable / Disable renegotiation support for connection when
  *                 initiated by peer

library/ssl_tls.c

@@ -3141,6 +3141,16 @@ int ssl_set_max_frag_len( ssl_context *ssl, unsigned char mfl_code )
     return( 0 );
 }
 
+int ssl_set_truncated_hmac( ssl_context *ssl )
+{
+    if( ssl->endpoint != SSL_IS_CLIENT )
+        return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
+    ssl->trunc_hmac = SSL_TRUNC_HMAC_ENABLED;
+
+    return( 0 );
+}
+
 void ssl_set_renegotiation( ssl_context *ssl, int renegotiation )
 {
     ssl->disable_renegotiation = renegotiation;

programs/ssl/ssl_client2.c

@@ -58,6 +58,7 @@
 #define DFL_MAX_VERSION         -1
 #define DFL_AUTH_MODE           SSL_VERIFY_OPTIONAL
 #define DFL_MFL_CODE            SSL_MAX_FRAG_LEN_NONE
+#define DFL_TRUNC_HMAC          0
 
 #define LONG_HEADER "User-agent: blah-blah-blah-blah-blah-blah-blah-blah-"   \
     "-01--blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-" \
@@ -94,6 +95,7 @@ struct options
     int max_version;            /* maximum protocol version accepted        */
     int auth_mode;              /* verify mode for connection               */
     unsigned char mfl_code;     /* code for maximum fragment length         */
+    int trunc_hmac;             /* negotiate truncated hmac or not          */
 } opt;
 
 static void my_debug( void *ctx, int level, const char *str )
@@ -191,6 +193,7 @@ static int my_verify( void *data, x509_cert *crt, int depth, int *flags )
     "                        options: none, optional, required\n" \
     "    max_frag_len=%%d     default: 16384 (tls default)" \
     "                        options: 512, 1024, 2048, 4096" \
+    "    trunc_hmac=%%d       default: 0 (disabled)\n"      \
     USAGE_PSK                                               \
     "\n"                                                    \
     "    force_ciphersuite=<name>    default: all enabled\n"\
@@ -281,6 +284,7 @@ int main( int argc, char *argv[] )
     opt.max_version         = DFL_MAX_VERSION;
     opt.auth_mode           = DFL_AUTH_MODE;
     opt.mfl_code            = DFL_MFL_CODE;
+    opt.trunc_hmac          = DFL_TRUNC_HMAC;
 
     for( i = 1; i < argc; i++ )
     {
@@ -416,6 +420,12 @@ int main( int argc, char *argv[] )
             else
                 goto usage;
         }
+        else if( strcmp( p, "trunc_hmac" ) == 0 )
+        {
+            opt.trunc_hmac = atoi( q );
+            if( opt.trunc_hmac < 0 || opt.trunc_hmac > 1 )
+                goto usage;
+        }
         else
             goto usage;
     }
@@ -623,6 +633,9 @@ int main( int argc, char *argv[] )
 
     ssl_set_max_frag_len( &ssl, opt.mfl_code );
 
+    if( opt.trunc_hmac != 0 )
+        ssl_set_truncated_hmac( &ssl );
+
     ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
     ssl_set_dbg( &ssl, my_debug, stdout );
     ssl_set_bio( &ssl, net_recv, &server_fd,