allow per-block rand bytes to be use independently from block MAC

git-svn-id: http://encfs.googlecode.com/svn/trunk@62 db9cf616-1c43-0410-9cb8-a902689de0d6

encfs/FileNode.cpp

@@ -80,7 +80,7 @@ FileNode::FileNode(DirNode *parent_, const FSConfigPtr &cfg,
     shared_ptr<FileIO> rawIO( new RawFileIO( _cname ) );
     io = shared_ptr<FileIO>( new CipherFileIO( rawIO, fsConfig ));
 
-    if(cfg->config->blockMACBytes)
+    if(cfg->config->blockMACBytes || cfg->config->blockMACRandBytes)
         io = shared_ptr<FileIO>(new MACFileIO(io, fsConfig));
 }
 

encfs/FileUtils.cpp

@@ -879,35 +879,31 @@ void selectBlockMAC(int *macBytes, int *macRandBytes)
 	"within a block will be caught and will cause a read error."));
 
     if(addMAC)
-    {
 	*macBytes = 8;
-
+    else
-	// xgroup(setup)
-	cout << _("Add random bytes to each block header?\n"
-	    "This adds a performance penalty, but ensures that blocks\n"
-	    "have different authentication codes.  Note that you can\n"
-	    "have the same benefits by enabling per-file initialization\n"
-	    "vectors, which does not come with as great of performance\n"
-	    "penalty. \n"
-	    "Select a number of bytes, from 0 (no random bytes) to 8: ");
-   
-        char answer[10];
-	int randSize = 0;
-	char *res = fgets( answer, sizeof(answer), stdin );
-	cout << "\n";
-
-	randSize = (res == 0 ? 0 : atoi( answer ));
-	if(randSize < 0)
-	    randSize = 0;
-	if(randSize > 8)
-	    randSize = 8;
-
-	*macRandBytes = randSize;
-    } else
-    {
 	*macBytes = 0;
-	*macRandBytes = 0;
+
-    }
+    // xgroup(setup)
+    cout << _("Add random bytes to each block header?\n"
+        "This adds a performance penalty, but ensures that blocks\n"
+        "have different authentication codes.  Note that you can\n"
+        "have the same benefits by enabling per-file initialization\n"
+        "vectors, which does not come with as great of performance\n"
+        "penalty. \n"
+        "Select a number of bytes, from 0 (no random bytes) to 8: ");
+
+    char answer[10];
+    int randSize = 0;
+    char *res = fgets( answer, sizeof(answer), stdin );
+    cout << "\n";
+
+    randSize = (res == 0 ? 0 : atoi( answer ));
+    if(randSize < 0)
+        randSize = 0;
+    if(randSize > 8)
+        randSize = 8;
+
+    *macRandBytes = randSize;
 }
 
 static
@@ -1305,7 +1301,7 @@ void showFSInfo( const boost::shared_ptr<EncFSConfig> &config )
 	cout << autosprintf(_("Salt Size: %i bits"), 
                 8*(int)config->salt.size()) << "\n";
     }
-    if(config->blockMACBytes)
+    if(config->blockMACBytes || config->blockMACRandBytes)
     {
         if(config->subVersion < 20040813)
 	{

encfs/MACFileIO.cpp

@@ -66,7 +66,7 @@ MACFileIO::MACFileIO( const shared_ptr<FileIO> &_base,
    , randBytes( cfg->config->blockMACRandBytes )
    , warnOnly( cfg->opts->forceDecode )
 {
-    rAssert( macBytes > 0 && macBytes <= 8 );
+    rAssert( macBytes >= 0 && macBytes <= 8 );
     rAssert( randBytes >= 0 );
     rLog(Info, "fs block size = %i, macBytes = %i, randBytes = %i",
 	    cfg->config->blockSize, 
@@ -183,17 +183,16 @@ ssize_t MACFileIO::readOneBlock( const IORequest &req ) const
     ssize_t readSize = base->read( tmp );
 
     // don't store zeros if configured for zero-block pass-through
-    bool skipBlock;
+    bool skipBlock = true;
     if( _allowHoles )
     {
-        skipBlock = true;
         for(int i=0; i<readSize; ++i)
             if(tmp.data[i] != 0)
             {
                 skipBlock = false;
                 break;
             }
-    } else
+    } else if(macBytes > 0)
        skipBlock = false; 
 
     if(readSize > headerSize)
@@ -257,20 +256,23 @@ bool MACFileIO::writeOneBlock( const IORequest &req )
 
     memset( newReq.data, 0, headerSize );
     memcpy( newReq.data + headerSize, req.data, req.dataLen );
-    if(randBytes)
+    if(randBytes > 0)
     {
 	if(!cipher->randomize( newReq.data+macBytes, randBytes, false ))
             return false;
     }
 
-    // compute the mac (which includes the random data) and fill it in
+    if(macBytes > 0)
-    uint64_t mac = cipher->MAC_64( newReq.data+macBytes, 
-	                           req.dataLen + randBytes, key );
-
-    for(int i=0; i<macBytes; ++i)
     {
-	newReq.data[i] = mac & 0xff;
+        // compute the mac (which includes the random data) and fill it in
-	mac >>= 8;
+        uint64_t mac = cipher->MAC_64( newReq.data+macBytes, 
+                req.dataLen + randBytes, key );
+
+        for(int i=0; i<macBytes; ++i)
+        {
+            newReq.data[i] = mac & 0xff;
+            mac >>= 8;
+        }
     }
 
     // now, we can let the next level have it..