svn commit: r1586977 - /cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java

[aa...@apache.org]

Author: aadamchik
Date: Sun Apr 13 13:28:06 2014
New Revision: 1586977

URL: http://svn.apache.org/r1586977
Log:
CAY-1925 cayenne-crypto: add optional compression to the encryption pipeline

splitting Header into a separate class

Added:
    cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java

Added: cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java
URL: http://svn.apache.org/viewvc/cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java?rev=1586977&view=auto
==============================================================================
--- cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java (added)
+++ cayenne/main/trunk/cayenne-crypto/src/main/java/org/apache/cayenne/crypto/transformer/bytes/Header.java Sun Apr 13 13:28:06 2014
@@ -0,0 +1,98 @@
+/*****************************************************************
+ *   Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ ****************************************************************/
+package org.apache.cayenne.crypto.transformer.bytes;
+
+import java.io.UnsupportedEncodingException;
+
+import org.apache.cayenne.crypto.CayenneCryptoException;
+
+/**
+ * Represents a header with metadata about the encrypted data. A header is
+ * prependend to each encrypted value, and itself is not encrypted.
+ * 
+ * @since 3.2
+ */
+class Header {
+
+    private static final String KEY_NAME_CHARSET = "UTF-8";
+
+    /**
+     * The size of a header byte[] block.
+     */
+    static final int HEADER_SIZE = 16;
+
+    /**
+     * The size of a key name within the header block.
+     */
+    static final int KEY_NAME_SIZE = 8;
+
+    /**
+     * Position of the key name within the header block.
+     */
+    static final int KEY_NAME_OFFSET = 8;
+
+    /**
+     * Position of the "flags" byte in the header.
+     */
+    static final int FLAGS_OFFSET = 0;
+
+    private byte[] data;
+
+    static Header create(String keyName) {
+        byte[] keyNameBytes;
+        try {
+            keyNameBytes = keyName.getBytes(KEY_NAME_CHARSET);
+        } catch (UnsupportedEncodingException e) {
+            throw new CayenneCryptoException("Can't encode in " + KEY_NAME_CHARSET, e);
+        }
+
+        byte[] data = new byte[HEADER_SIZE];
+
+        if (keyNameBytes.length <= KEY_NAME_SIZE) {
+            System.arraycopy(keyNameBytes, 0, data, KEY_NAME_OFFSET, keyNameBytes.length);
+        } else {
+            throw new CayenneCryptoException("Key name '" + keyName
+                    + "' is too long. Its UTF8-encoded form should not exceed " + KEY_NAME_SIZE + " bytes");
+        }
+
+        return create(data);
+
+    }
+
+    static Header create(byte[] data) {
+
+        if (data.length != HEADER_SIZE) {
+            throw new CayenneCryptoException("Unexpected header data size: " + data.length + ", expected size is "
+                    + HEADER_SIZE);
+        }
+
+        Header h = new Header();
+        h.data = data;
+        return h;
+    }
+
+    // private constructor... construction is done via factory methods...
+    private Header() {
+
+    }
+
+    byte[] getData() {
+        return data;
+    }
+}