Add KeePass2RandomStream class.

It's responsible for processing protected strings in kdbx files.

src/CMakeLists.txt

@@ -39,6 +39,7 @@ set(keepassx_SOURCES
     crypto/SymmetricCipherGcrypt.cpp
     crypto/SymmetricCipherSalsa20.cpp
     format/KeePass2.h
+    format/KeePass2RandomStream.cpp
     format/KeePass2Reader.cpp
     format/KeePass2Writer.cpp
     format/KeePass2XmlReader.cpp

src/format/KeePass2RandomStream.cpp

@@ -0,0 +1,79 @@
+/*
+ *  Copyright (C) 2010 Felix Geyer <debfx@fobos.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "KeePass2RandomStream.h"
+
+#include "format/KeePass2.h"
+#include "crypto/CryptoHash.h"
+
+KeePass2RandomStream::KeePass2RandomStream(QByteArray key)
+    : m_cipher(SymmetricCipher::Salsa20, SymmetricCipher::Stream, SymmetricCipher::Encrypt,
+          CryptoHash::hash(key, CryptoHash::Sha256), KeePass2::INNER_STREAM_SALSA20_IV)
+    , m_offset(0)
+{
+}
+
+QByteArray KeePass2RandomStream::randomBytes(int size)
+{
+    QByteArray result;
+
+    int bytesRemaining = size;
+
+    while (bytesRemaining > 0) {
+        if (m_buffer.size() == m_offset) {
+            loadBlock();
+        }
+
+        int bytesToCopy = qMin(bytesRemaining, m_buffer.size() - m_offset);
+        result.append(m_buffer.mid(m_offset, bytesToCopy));
+        m_offset += bytesToCopy;
+        bytesRemaining -= bytesToCopy;
+    }
+
+    return result;
+}
+
+QByteArray KeePass2RandomStream::process(const QByteArray& data)
+{
+    QByteArray randomData = randomBytes(data.size());
+    QByteArray result;
+    result.resize(data.size());
+
+    for (int i=0; i<data.size(); i++) {
+        result[i] = data[i] ^ randomData[i];
+    }
+
+    return result;
+}
+
+void KeePass2RandomStream::processInPlace(QByteArray& data)
+{
+    QByteArray randomData = randomBytes(data.size());
+
+    for (int i=0; i<data.size(); i++) {
+        data[i] = data[i] ^ randomData[i];
+    }
+}
+
+void KeePass2RandomStream::loadBlock()
+{
+    Q_ASSERT(m_offset == m_buffer.size());
+
+    m_buffer.fill('\0', m_cipher.blockSize());
+    m_cipher.processInPlace(m_buffer);
+    m_offset = 0;
+}

src/format/KeePass2RandomStream.h

@@ -0,0 +1,41 @@
+/*
+ *  Copyright (C) 2010 Felix Geyer <debfx@fobos.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSX_KEEPASS2RANDOMSTREAM_H
+#define KEEPASSX_KEEPASS2RANDOMSTREAM_H
+
+#include <QtCore/QByteArray>
+
+#include "crypto/SymmetricCipher.h"
+
+class KeePass2RandomStream
+{
+public:
+    KeePass2RandomStream(QByteArray key);
+    QByteArray randomBytes(int size);
+    QByteArray process(const QByteArray& data);
+    void processInPlace(QByteArray& data);
+
+private:
+    void loadBlock();
+
+    SymmetricCipher m_cipher;
+    QByteArray m_buffer;
+    int m_offset;
+};
+
+#endif // KEEPASSX_KEEPASS2RANDOMSTREAM_H