More comments; moved the encryption system to unstable.

1 files changed, 59 insertions, 0 deletions

diff --git a/src/unstable/ciphermodecfb.h b/src/unstable/ciphermodecfb.h
new file mode 100644
index 0000000..1c9c5e9
--- /dev/null
+++ b/src/unstable/ciphermodecfb.h
@@ -0,0 +1,59 @@
+#ifndef BU_MODE_CFB_H
+#define BU_MODE_CFB_H
+
+#include "bu/filter.h"
+#include "bu/string.h"
+
+namespace Bu
+{
+    /**
+     * Cipher Feedback mode.  This is very similar to the Cipher-block chaining
+     * mode, with a slight tweak (Bu::CipherModeCbc).  Each block is still
+     * dependant on all previous blocks.  Any corruption and the entire stream
+     * will be corrupt.
+     */
+    template<int iBlockSize, typename CipherType>
+    class CipherModeCfb : public CipherType
+    {
+    public:
+        CipherModeCfb(class Stream &rNext ) :
+            CipherType( rNext ),
+            bStart( true )
+        {
+            memset( aVector, 0, iBlockSize );
+        }
+
+        virtual ~CipherModeCfb()
+        {
+        }
+
+        void setIv( const Bu::String &sIv )
+        {
+            memcpy( aVector, sIv.getStr(), iBlockSize );
+        }
+
+    protected:
+        void decipher( void *pBuf )
+        {
+            uint8_t aTmp[iBlockSize];
+            memcpy( aTmp, pBuf, iBlockSize );
+            CipherType::encipher( aVector );
+            for( int j = 0; j < iBlockSize; j++ )
+                ((uint8_t *)pBuf)[j] ^= aVector[j];
+            memcpy( aVector, aTmp, iBlockSize );
+        }
+
+        void encipher( void *pBuf )
+        {
+            CipherType::encipher( aVector );
+            for( int j = 0; j < iBlockSize; j++ )
+                aVector[j] = ((uint8_t *)pBuf)[j] ^= aVector[j];
+        }
+
+    private:
+        bool bStart;
+        uint8_t aVector[iBlockSize];
+    };
+};
+
+#endif