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#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
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