Add eap-tls key derivation in the examples.

Add support for eap-tls key derivation functionality,
in `ssl_client2` and `ssl_server2` reference applications.

library/ssl_tls.c

@@ -1270,7 +1270,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
     {
         ssl->conf->f_export_keys_ext( ssl->conf->p_export_keys,
                                       session->master, keyblk,
-                                      mac_key_len, transform->keylen,
+                                      mac_key_len, keylen,
                                       iv_copy_len, handshake->tls_prf,
                                       handshake->randbytes + 32,
                                       handshake->randbytes );

programs/ssl/ssl_client2.c

@@ -126,7 +126,7 @@ int main( void )
 #define DFL_EXTENDED_MS         -1
 #define DFL_ETM                 -1
 #define DFL_CA_CALLBACK         0
-
+#define DFL_EAP_TLS             0
 
 #define GET_REQUEST "GET %s HTTP/1.0\r\nExtra-header: "
 #define GET_REQUEST_END "\r\n\r\n"
@@ -204,6 +204,13 @@ int main( void )
 #define USAGE_TICKETS ""
 #endif /* MBEDTLS_SSL_SESSION_TICKETS */
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+#define USAGE_EAP_TLS                                       \
+    "    eap_tls=%%d          default: 0 (disabled)\n"
+#else
+#define USAGE_EAP_TLS ""
+#endif /* MBEDTLS_SSL_EXPORT_KEYS */
+
 #if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
 #define USAGE_TRUNC_HMAC                                    \
     "    trunc_hmac=%%d       default: library default\n"
@@ -348,6 +355,7 @@ int main( void )
     "    reco_delay=%%d       default: 0 seconds\n"         \
     "    reconnect_hard=%%d   default: 0 (disabled)\n"      \
     USAGE_TICKETS                                           \
+    USAGE_EAP_TLS                                           \
     USAGE_MAX_FRAG_LEN                                      \
     USAGE_TRUNC_HMAC                                        \
     USAGE_CONTEXT_CRT_CB                                    \
@@ -448,10 +456,44 @@ struct options
     int extended_ms;            /* negotiate extended master secret?        */
     int etm;                    /* negotiate encrypt then mac?              */
     int context_crt_cb;         /* use context-specific CRT verify callback */
+    int eap_tls;                /* derive EAP-TLS keying material?          */
 } opt;
 
 int query_config( const char *config );
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+typedef struct eap_tls_keys
+{
+    unsigned char master_secret[48];
+    unsigned char randbytes[64];
+    mbedtls_ssl_tls_prf *tls_prf;
+} eap_tls_keys;
+
+static int eap_tls_key_derivation ( void *p_expkey,
+                                    const unsigned char *ms,
+                                    const unsigned char *kb,
+                                    size_t maclen,
+                                    size_t keylen,
+                                    size_t ivlen,
+                                    mbedtls_ssl_tls_prf *tls_prf,
+                                    unsigned char client_random[32],
+                                    unsigned char server_random[32] )
+{
+    eap_tls_keys *keys = (eap_tls_keys *)p_expkey;
+
+    ( ( void ) kb );
+    ( ( void ) maclen );
+    ( ( void ) keylen );
+    ( ( void ) ivlen );
+    memcpy( keys->master_secret, ms, sizeof( keys->master_secret ) );
+    memcpy( keys->randbytes, client_random, 32 );
+    memcpy( keys->randbytes + 32, server_random, 32 );
+    keys->tls_prf = tls_prf;
+
+    return( 0 );
+}
+#endif
+
 static void my_debug( void *ctx, int level,
                       const char *file, int line,
                       const char *str )
@@ -713,6 +755,12 @@ int main( int argc, char *argv[] )
 #endif
     char *p, *q;
     const int *list;
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    unsigned char eap_tls_keymaterial[16];
+    unsigned char eap_tls_iv[8];
+    const char* eap_tls_label = "client EAP encryption";
+    eap_tls_keys eap_tls_keying;
+#endif
 
     /*
      * Make sure memory references are valid.
@@ -818,6 +866,7 @@ int main( int argc, char *argv[] )
     opt.extended_ms         = DFL_EXTENDED_MS;
     opt.etm                 = DFL_ETM;
     opt.dgram_packing       = DFL_DGRAM_PACKING;
+    opt.eap_tls             = DFL_EAP_TLS;
 
     for( i = 1; i < argc; i++ )
     {
@@ -1176,6 +1225,12 @@ int main( int argc, char *argv[] )
         {
             return query_config( q );
         }
+        else if( strcmp( p, "eap_tls" ) == 0 )
+        {
+            opt.eap_tls = atoi( q );
+            if( opt.eap_tls < 0 || opt.eap_tls > 1 )
+                goto usage;
+        }
         else
             goto usage;
     }
@@ -1652,6 +1707,12 @@ int main( int argc, char *argv[] )
         mbedtls_ssl_conf_encrypt_then_mac( &conf, opt.etm );
 #endif
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    if( opt.eap_tls != 0 )
+        mbedtls_ssl_conf_export_keys_ext_cb( &conf, eap_tls_key_derivation,
+                                             &eap_tls_keying );
+#endif
+
 #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
     if( opt.recsplit != DFL_RECSPLIT )
         mbedtls_ssl_conf_cbc_record_splitting( &conf, opt.recsplit
@@ -1917,6 +1978,40 @@ int main( int argc, char *argv[] )
     }
 #endif
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    if( opt.eap_tls != 0 &&
+        eap_tls_keying.tls_prf != NULL )
+    {
+        size_t j = 0;
+        eap_tls_keying.tls_prf( eap_tls_keying.master_secret,
+                                sizeof( eap_tls_keying.master_secret ),
+                                eap_tls_label,
+                                eap_tls_keying.randbytes,
+                                sizeof( eap_tls_keying.randbytes ),
+                                eap_tls_keymaterial,
+                                sizeof( eap_tls_keymaterial ) );
+        mbedtls_printf( "    EAP-TLS key material is:" );
+        for( j = 0; j < sizeof( eap_tls_keymaterial ); j++ )
+        {
+            if( j % 8 == 0 )
+                mbedtls_printf("\n    ");
+            mbedtls_printf("%02x ", eap_tls_keymaterial[j] );
+        }
+        mbedtls_printf("\n");
+
+        eap_tls_keying.tls_prf( NULL, 0, eap_tls_label, eap_tls_keying.randbytes,
+                                sizeof( eap_tls_keying.randbytes ), eap_tls_iv,
+                                sizeof( eap_tls_iv  ) );
+        mbedtls_printf( "    EAP-TLS IV is:" );
+        for( j = 0; j < sizeof( eap_tls_iv ); j++ )
+        {
+            if( j % 8 == 0 )
+                mbedtls_printf("\n    ");
+            mbedtls_printf("%02x ", eap_tls_iv[j] );
+        }
+        mbedtls_printf("\n");
+    }
+#endif
     if( opt.reconnect != 0 )
     {
         mbedtls_printf("  . Saving session for reuse..." );

programs/ssl/ssl_server2.c

@@ -168,6 +168,7 @@ int main( void )
 #define DFL_EXTENDED_MS         -1
 #define DFL_ETM                 -1
 #define DFL_CA_CALLBACK         0
+#define DFL_EAP_TLS             0
 
 #define LONG_RESPONSE "<p>01-blah-blah-blah-blah-blah-blah-blah-blah-blah\r\n" \
     "02-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah\r\n"  \
@@ -281,6 +282,13 @@ int main( void )
 #define USAGE_TICKETS ""
 #endif /* MBEDTLS_SSL_SESSION_TICKETS */
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+#define USAGE_EAP_TLS                                       \
+    "    eap_tls=%%d          default: 0 (disabled)\n"
+#else
+#define USAGE_EAP_TLS ""
+#endif /* MBEDTLS_SSL_EXPORT_KEYS */
+
 #if defined(MBEDTLS_SSL_CACHE_C)
 #define USAGE_CACHE                                             \
     "    cache_max=%%d        default: cache default (50)\n"    \
@@ -442,6 +450,7 @@ int main( void )
     "    exchanges=%%d        default: 1\n"                 \
     "\n"                                                    \
     USAGE_TICKETS                                           \
+    USAGE_EAP_TLS                                           \
     USAGE_CACHE                                             \
     USAGE_MAX_FRAG_LEN                                      \
     USAGE_TRUNC_HMAC                                        \
@@ -563,10 +572,44 @@ struct options
     int dtls_mtu;               /* UDP Maximum tranport unit for DTLS       */
     int dgram_packing;          /* allow/forbid datagram packing            */
     int badmac_limit;           /* Limit of records with bad MAC            */
+    int eap_tls;                /* derive EAP-TLS keying material?          */
 } opt;
 
 int query_config( const char *config );
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+typedef struct eap_tls_keys
+{
+    unsigned char master_secret[48];
+    unsigned char randbytes[64];
+    mbedtls_ssl_tls_prf *tls_prf;
+} eap_tls_keys;
+
+static int eap_tls_key_derivation ( void *p_expkey,
+                                    const unsigned char *ms,
+                                    const unsigned char *kb,
+                                    size_t maclen,
+                                    size_t keylen,
+                                    size_t ivlen,
+                                    mbedtls_ssl_tls_prf *tls_prf,
+                                    unsigned char client_random[32],
+                                    unsigned char server_random[32] )
+{
+    eap_tls_keys *keys = (eap_tls_keys *)p_expkey;
+
+    ( ( void ) kb );
+    ( ( void ) maclen );
+    ( ( void ) keylen );
+    ( ( void ) ivlen );
+    memcpy( keys->master_secret, ms, sizeof( keys->master_secret ) );
+    memcpy( keys->randbytes, client_random, 32 );
+    memcpy( keys->randbytes + 32, server_random, 32 );
+    keys->tls_prf = tls_prf;
+
+    return( 0 );
+}
+#endif
+
 static void my_debug( void *ctx, int level,
                       const char *file, int line,
                       const char *str )
@@ -1444,6 +1487,12 @@ int main( int argc, char *argv[] )
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
     psa_status_t status;
 #endif
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    unsigned char eap_tls_keymaterial[16];
+    unsigned char eap_tls_iv[8];
+    const char* eap_tls_label = "client EAP encryption";
+    eap_tls_keys eap_tls_keying;
+#endif
 
 #if defined(MBEDTLS_MEMORY_BUFFER_ALLOC_C)
     mbedtls_memory_buffer_alloc_init( alloc_buf, sizeof(alloc_buf) );
@@ -1585,6 +1634,7 @@ int main( int argc, char *argv[] )
     opt.badmac_limit        = DFL_BADMAC_LIMIT;
     opt.extended_ms         = DFL_EXTENDED_MS;
     opt.etm                 = DFL_ETM;
+    opt.eap_tls             = DFL_EAP_TLS;
 
     for( i = 1; i < argc; i++ )
     {
@@ -1975,6 +2025,12 @@ int main( int argc, char *argv[] )
         {
             return query_config( q );
         }
+        else if( strcmp( p, "eap_tls" ) == 0 )
+        {
+            opt.eap_tls = atoi( q );
+            if( opt.eap_tls < 0 || opt.eap_tls > 1 )
+                goto usage;
+        }
         else
             goto usage;
     }
@@ -2537,6 +2593,12 @@ int main( int argc, char *argv[] )
         mbedtls_ssl_conf_encrypt_then_mac( &conf, opt.etm );
 #endif
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    if( opt.eap_tls != 0 )
+        mbedtls_ssl_conf_export_keys_ext_cb( &conf, eap_tls_key_derivation,
+                                             &eap_tls_keying );
+#endif
+
 #if defined(MBEDTLS_SSL_ALPN)
     if( opt.alpn_string != NULL )
         if( ( ret = mbedtls_ssl_conf_alpn_protocols( &conf, alpn_list ) ) != 0 )
@@ -3117,6 +3179,40 @@ handshake:
     }
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
+#if defined(MBEDTLS_SSL_EXPORT_KEYS)
+    if( opt.eap_tls != 0 &&
+        eap_tls_keying.tls_prf != NULL )
+    {
+        size_t j = 0;
+        eap_tls_keying.tls_prf( eap_tls_keying.master_secret,
+                                sizeof( eap_tls_keying.master_secret ),
+                                eap_tls_label,
+                                eap_tls_keying.randbytes,
+                                sizeof( eap_tls_keying.randbytes ),
+                                eap_tls_keymaterial,
+                                sizeof( eap_tls_keymaterial ) );
+        mbedtls_printf( "    EAP-TLS key material is:" );
+        for( j = 0; j < sizeof( eap_tls_keymaterial ); j++ )
+        {
+            if( j % 8 == 0 )
+                mbedtls_printf("\n    ");
+            mbedtls_printf("%02x ", eap_tls_keymaterial[j] );
+        }
+        mbedtls_printf("\n");
+
+        eap_tls_keying.tls_prf( NULL, 0, eap_tls_label, eap_tls_keying.randbytes,
+                                sizeof( eap_tls_keying.randbytes ), eap_tls_iv,
+                                sizeof( eap_tls_iv  ) );
+        mbedtls_printf( "    EAP-TLS IV is:" );
+        for( j = 0; j < sizeof( eap_tls_iv ); j++ )
+        {
+            if( j % 8 == 0 )
+                mbedtls_printf("\n    ");
+            mbedtls_printf("%02x ", eap_tls_iv[j] );
+        }
+        mbedtls_printf("\n");
+    }
+#endif
     if( opt.exchanges == 0 )
         goto close_notify;