filters.h

研读AxCrypt对加解密的处理方法

//! simple proxy filter that doesn't modify the underlying filter's input or output
class CRYPTOPP_DLL SimpleProxyFilter : public ProxyFilter
{
public:
	SimpleProxyFilter(BufferedTransformation *filter, BufferedTransformation *attachment)
		: ProxyFilter(filter, 0, 0, attachment) {}

	void FirstPut(const byte *) {}
	void LastPut(const byte *, unsigned int) {m_filter->MessageEnd();}
};

//! proxy for the filter created by PK_Encryptor::CreateEncryptionFilter
/*! This class is here just to provide symmetry with VerifierFilter. */
class CRYPTOPP_DLL PK_EncryptorFilter : public SimpleProxyFilter
{
public:
	PK_EncryptorFilter(RandomNumberGenerator &rng, const PK_Encryptor &encryptor, BufferedTransformation *attachment = NULL)
		: SimpleProxyFilter(encryptor.CreateEncryptionFilter(rng), attachment) {}
};

//! proxy for the filter created by PK_Decryptor::CreateDecryptionFilter
/*! This class is here just to provide symmetry with SignerFilter. */
class CRYPTOPP_DLL PK_DecryptorFilter : public SimpleProxyFilter
{
public:
	PK_DecryptorFilter(RandomNumberGenerator &rng, const PK_Decryptor &decryptor, BufferedTransformation *attachment = NULL)
		: SimpleProxyFilter(decryptor.CreateDecryptionFilter(rng), attachment) {}
};

//! Append input to a string object
template <class T>
class StringSinkTemplate : public Bufferless<Sink>
{
public:
	// VC60 workaround: no T::char_type
	typedef typename T::traits_type::char_type char_type;

	StringSinkTemplate(T &output)
		: m_output(&output) {assert(sizeof(output[0])==1);}

	void IsolatedInitialize(const NameValuePairs &parameters)
		{if (!parameters.GetValue("OutputStringPointer", m_output)) throw InvalidArgument("StringSink: OutputStringPointer not specified");}

	unsigned int Put2(const byte *begin, unsigned int length, int messageEnd, bool blocking)
	{
		if (length > 0)
		{
			typename T::size_type size = m_output->size();
			if (length < size && size + length > m_output->capacity())
				m_output->reserve(2*size);
		m_output->append((const char_type *)begin, (const char_type *)begin+length);
		}
		return 0;
	}

private:	
	T *m_output;
};

//! Append input to an std::string
CRYPTOPP_DLL_TEMPLATE_CLASS StringSinkTemplate<std::string>;
typedef StringSinkTemplate<std::string> StringSink;

//! Copy input to a memory buffer
class CRYPTOPP_DLL ArraySink : public Bufferless<Sink>
{
public:
	ArraySink(const NameValuePairs &parameters = g_nullNameValuePairs) {IsolatedInitialize(parameters);}
	ArraySink(byte *buf, unsigned int size) : m_buf(buf), m_size(size), m_total(0) {}

	unsigned int AvailableSize() {return m_size - STDMIN(m_total, (unsigned long)m_size);}
	unsigned long TotalPutLength() {return m_total;}

	void IsolatedInitialize(const NameValuePairs &parameters);
	byte * CreatePutSpace(unsigned int &size);
	unsigned int Put2(const byte *begin, unsigned int length, int messageEnd, bool blocking);

protected:
	byte *m_buf;
	unsigned int m_size;
	unsigned long m_total;
};

//! Xor input to a memory buffer
class CRYPTOPP_DLL ArrayXorSink : public ArraySink
{
public:
	ArrayXorSink(byte *buf, unsigned int size)
		: ArraySink(buf, size) {}

	unsigned int Put2(const byte *begin, unsigned int length, int messageEnd, bool blocking);
	byte * CreatePutSpace(unsigned int &size) {return BufferedTransformation::CreatePutSpace(size);}
};

//! string-based implementation of Store interface
class StringStore : public Store
{
public:
	StringStore(const char *string = NULL)
		{StoreInitialize(MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}
	StringStore(const byte *string, unsigned int length)
		{StoreInitialize(MakeParameters("InputBuffer", ConstByteArrayParameter(string, length)));}
	template <class T> StringStore(const T &string)
		{StoreInitialize(MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}

	CRYPTOPP_DLL unsigned int TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel=NULL_CHANNEL, bool blocking=true);
	CRYPTOPP_DLL unsigned int CopyRangeTo2(BufferedTransformation &target, unsigned long &begin, unsigned long end=ULONG_MAX, const std::string &channel=NULL_CHANNEL, bool blocking=true) const;

private:
	CRYPTOPP_DLL void StoreInitialize(const NameValuePairs &parameters);

	const byte *m_store;
	unsigned int m_length, m_count;
};

//! RNG-based implementation of Source interface
class CRYPTOPP_DLL RandomNumberStore : public Store
{
public:
	RandomNumberStore()
		: m_rng(NULL), m_length(0), m_count(0) {}

	RandomNumberStore(RandomNumberGenerator &rng, unsigned long length)
		: m_rng(&rng), m_length(length), m_count(0) {}

	bool AnyRetrievable() const {return MaxRetrievable() != 0;}
	unsigned long MaxRetrievable() const {return m_length-m_count;}

	unsigned int TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel=NULL_CHANNEL, bool blocking=true);
	unsigned int CopyRangeTo2(BufferedTransformation &target, unsigned long &begin, unsigned long end=ULONG_MAX, const std::string &channel=NULL_CHANNEL, bool blocking=true) const
	{
		throw NotImplemented("RandomNumberStore: CopyRangeTo2() is not supported by this store");
	}

private:
	void StoreInitialize(const NameValuePairs &parameters);

	RandomNumberGenerator *m_rng;
	int m_length;
	unsigned long m_count;
};

//! empty store
class CRYPTOPP_DLL NullStore : public Store
{
public:
	NullStore(unsigned long size = ULONG_MAX) : m_size(size) {}
	void StoreInitialize(const NameValuePairs &parameters) {}
	unsigned long MaxRetrievable() const {return m_size;}
	unsigned int TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel=NULL_CHANNEL, bool blocking=true);
	unsigned int CopyRangeTo2(BufferedTransformation &target, unsigned long &begin, unsigned long end=ULONG_MAX, const std::string &channel=NULL_CHANNEL, bool blocking=true) const;

private:
	unsigned long m_size;
};

//! A Filter that pumps data into its attachment as input
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE Source : public InputRejecting<Filter>
{
public:
	Source(BufferedTransformation *attachment = NULL)
		{Source::Detach(attachment);}

	unsigned long Pump(unsigned long pumpMax=ULONG_MAX)
		{Pump2(pumpMax); return pumpMax;}
	unsigned int PumpMessages(unsigned int count=UINT_MAX)
		{PumpMessages2(count); return count;}
	void PumpAll()
		{PumpAll2();}
	virtual unsigned int Pump2(unsigned long &byteCount, bool blocking=true) =0;
	virtual unsigned int PumpMessages2(unsigned int &messageCount, bool blocking=true) =0;
	virtual unsigned int PumpAll2(bool blocking=true);
	virtual bool SourceExhausted() const =0;

protected:
	void SourceInitialize(bool pumpAll, const NameValuePairs &parameters)
	{
		IsolatedInitialize(parameters);
		if (pumpAll)
			PumpAll();
	}
};

//! Turn a Store into a Source
template <class T>
class SourceTemplate : public Source
{
public:
	SourceTemplate<T>(BufferedTransformation *attachment)
		: Source(attachment) {}
	void IsolatedInitialize(const NameValuePairs &parameters)
		{m_store.IsolatedInitialize(parameters);}
	unsigned int Pump2(unsigned long &byteCount, bool blocking=true)
		{return m_store.TransferTo2(*AttachedTransformation(), byteCount, NULL_CHANNEL, blocking);}
	unsigned int PumpMessages2(unsigned int &messageCount, bool blocking=true)
		{return m_store.TransferMessagesTo2(*AttachedTransformation(), messageCount, NULL_CHANNEL, blocking);}
	unsigned int PumpAll2(bool blocking=true)
		{return m_store.TransferAllTo2(*AttachedTransformation(), NULL_CHANNEL, blocking);}
	bool SourceExhausted() const
		{return !m_store.AnyRetrievable() && !m_store.AnyMessages();}
	void SetAutoSignalPropagation(int propagation)
		{m_store.SetAutoSignalPropagation(propagation);}
	int GetAutoSignalPropagation() const
		{return m_store.GetAutoSignalPropagation();}

protected:
	T m_store;
};

//! string-based implementation of Source interface
class CRYPTOPP_DLL StringSource : public SourceTemplate<StringStore>
{
public:
	StringSource(BufferedTransformation *attachment = NULL)
		: SourceTemplate<StringStore>(attachment) {}
	StringSource(const char *string, bool pumpAll, BufferedTransformation *attachment = NULL)
		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}
	StringSource(const byte *string, unsigned int length, bool pumpAll, BufferedTransformation *attachment = NULL)
		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string, length)));}
	StringSource(const std::string &string, bool pumpAll, BufferedTransformation *attachment = NULL)
		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}
};

//! RNG-based implementation of Source interface
class CRYPTOPP_DLL RandomNumberSource : public SourceTemplate<RandomNumberStore>
{
public:
	RandomNumberSource(RandomNumberGenerator &rng, int length, bool pumpAll, BufferedTransformation *attachment = NULL)
		: SourceTemplate<RandomNumberStore>(attachment) 
		{SourceInitialize(pumpAll, MakeParameters("RandomNumberGeneratorPointer", &rng)("RandomNumberStoreSize", length));}
};

NAMESPACE_END

#endif