modes.h

Crypto++是一个非常强大的密码学库,主要是功能全

#ifndef CRYPTOPP_MODES_H
#define CRYPTOPP_MODES_H

/*! \file
*/

#include "cryptlib.h"
#include "secblock.h"
#include "misc.h"
#include "strciphr.h"
#include "argnames.h"

NAMESPACE_BEGIN(CryptoPP)

//! Cipher mode documentation. See NIST SP 800-38A for definitions of these modes.

/*! Each class derived from this one defines two types, Encryption and Decryption, 
	both of which implement the SymmetricCipher interface.
	For each mode there are two classes, one of which is a template class,
	and the other one has a name that ends in "_ExternalCipher".
	The "external cipher" mode objects hold a reference to the underlying block cipher,
	instead of holding an instance of it. The reference must be passed in to the constructor.
	For the "cipher holder" classes, the CIPHER template parameter should be a class
	derived from BlockCipherDocumentation, for example DES or AES.
*/
struct CipherModeDocumentation : public SymmetricCipherDocumentation
{
};

class CRYPTOPP_DLL CipherModeBase : public SymmetricCipher
{
public:
	unsigned int MinKeyLength() const {return m_cipher->MinKeyLength();}
	unsigned int MaxKeyLength() const {return m_cipher->MaxKeyLength();}
	unsigned int DefaultKeyLength() const {return m_cipher->DefaultKeyLength();}
	unsigned int GetValidKeyLength(unsigned int n) const {return m_cipher->GetValidKeyLength(n);}
	bool IsValidKeyLength(unsigned int n) const {return m_cipher->IsValidKeyLength(n);}

	void SetKey(const byte *key, unsigned int length, const NameValuePairs &params = g_nullNameValuePairs);

	unsigned int OptimalDataAlignment() const {return BlockSize();}

	unsigned int IVSize() const {return BlockSize();}
	void GetNextIV(byte *IV);

protected:
	inline unsigned int BlockSize() const {assert(m_register.size() > 0); return m_register.size();}
	void SetIV(const byte *iv);
	virtual void SetFeedbackSize(unsigned int feedbackSize)
	{
		if (!(feedbackSize == 0 || feedbackSize == BlockSize()))
			throw InvalidArgument("CipherModeBase: feedback size cannot be specified for this cipher mode");
	}
	virtual void ResizeBuffers()
	{
		m_register.New(m_cipher->BlockSize());
	}
	virtual void UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length) =0;

	BlockCipher *m_cipher;
	SecByteBlock m_register;
};

template <class POLICY_INTERFACE>
class ModePolicyCommonTemplate : public CipherModeBase, public POLICY_INTERFACE
{
	unsigned int GetAlignment() const {return m_cipher->BlockAlignment();}
	void CipherSetKey(const NameValuePairs &params, const byte *key, unsigned int length);
};

template <class POLICY_INTERFACE>
void ModePolicyCommonTemplate<POLICY_INTERFACE>::CipherSetKey(const NameValuePairs &params, const byte *key, unsigned int length)
{
	m_cipher->SetKey(key, length, params);
	ResizeBuffers();
	int feedbackSize = params.GetIntValueWithDefault(Name::FeedbackSize(), 0);
	SetFeedbackSize(feedbackSize);
	const byte *iv = params.GetValueWithDefault(Name::IV(), (const byte *)NULL);
	SetIV(iv);
}

CRYPTOPP_DLL_TEMPLATE_CLASS ModePolicyCommonTemplate<CFB_CipherAbstractPolicy>;
CRYPTOPP_DLL_TEMPLATE_CLASS ModePolicyCommonTemplate<AdditiveCipherAbstractPolicy>;

class CRYPTOPP_DLL CFB_ModePolicy : public ModePolicyCommonTemplate<CFB_CipherAbstractPolicy>
{
public:
	IV_Requirement IVRequirement() const {return RANDOM_IV;}

protected:
	unsigned int GetBytesPerIteration() const {return m_feedbackSize;}
	byte * GetRegisterBegin() {return m_register + BlockSize() - m_feedbackSize;}
	void TransformRegister()
	{
		m_cipher->ProcessBlock(m_register, m_temp);
		memmove(m_register, m_register+m_feedbackSize, BlockSize()-m_feedbackSize);
		memcpy(m_register+BlockSize()-m_feedbackSize, m_temp, m_feedbackSize);
	}
	void CipherResynchronize(const byte *iv)
	{
		memcpy(m_register, iv, BlockSize());
		TransformRegister();
	}
	void SetFeedbackSize(unsigned int feedbackSize)
	{
		if (feedbackSize > BlockSize())
			throw InvalidArgument("CFB_Mode: invalid feedback size");
		m_feedbackSize = feedbackSize ? feedbackSize : BlockSize();
	}
	void ResizeBuffers()
	{
		CipherModeBase::ResizeBuffers();
		m_temp.New(BlockSize());
	}

	SecByteBlock m_temp;
	unsigned int m_feedbackSize;
};

class CRYPTOPP_DLL OFB_ModePolicy : public ModePolicyCommonTemplate<AdditiveCipherAbstractPolicy>
{
public:
	bool IsRandomAccess() const {return false;}
	IV_Requirement IVRequirement() const {return STRUCTURED_IV;}

private:
	unsigned int GetBytesPerIteration() const {return BlockSize();}
	unsigned int GetIterationsToBuffer() const {return 1;}
	void WriteKeystream(byte *keystreamBuffer, unsigned int iterationCount)
	{
		assert(iterationCount == 1);
		m_cipher->ProcessBlock(keystreamBuffer);
		memcpy(m_register, keystreamBuffer, BlockSize());
	}
	void CipherResynchronize(byte *keystreamBuffer, const byte *iv)
	{
		memcpy(keystreamBuffer, iv, BlockSize());
		memcpy(m_register, keystreamBuffer, BlockSize());
	}
};

class CRYPTOPP_DLL CTR_ModePolicy : public ModePolicyCommonTemplate<AdditiveCipherAbstractPolicy>
{
public:
	bool IsRandomAccess() const {return true;}
	IV_Requirement IVRequirement() const {return STRUCTURED_IV;}
	void GetNextIV(byte *IV);

private:
	unsigned int GetBytesPerIteration() const {return BlockSize();}
	unsigned int GetIterationsToBuffer() const {return m_cipher->OptimalNumberOfParallelBlocks();}
	void WriteKeystream(byte *buffer, unsigned int iterationCount)
		{OperateKeystream(WRITE_KEYSTREAM, buffer, NULL, iterationCount);}
	bool CanOperateKeystream() const {return true;}
	void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, unsigned int iterationCount);
	void CipherResynchronize(byte *keystreamBuffer, const byte *iv);
	void SeekToIteration(dword iterationCount);

	static inline void IncrementCounterByOne(byte *output, const byte *input, unsigned int s)
	{
		for (int i=s-1, carry=1; i>=0 && carry; i--)
    		carry = !(output[i] = input[i]+1);
	}
	inline void ProcessMultipleBlocks(byte *output, const byte *input, unsigned int n)
	{
		unsigned int s = BlockSize(), j = 0;
		for (unsigned int i=1; i<n; i++, j+=s)
			IncrementCounterByOne(m_counterArray + j + s, m_counterArray + j, s);
		m_cipher->ProcessAndXorMultipleBlocks(m_counterArray, input, output, n);
		IncrementCounterByOne(m_counterArray, m_counterArray + s*(n-1), s);
	}

	SecByteBlock m_counterArray;
};

class CRYPTOPP_DLL BlockOrientedCipherModeBase : public CipherModeBase
{
public:
	void UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length);
	unsigned int MandatoryBlockSize() const {return BlockSize();}
	bool IsRandomAccess() const {return false;}
	bool IsSelfInverting() const {return false;}
	bool IsForwardTransformation() const {return m_cipher->IsForwardTransformation();}
	void Resynchronize(const byte *iv) {memcpy(m_register, iv, BlockSize());}
	void ProcessData(byte *outString, const byte *inString, unsigned int length);

protected:
	bool RequireAlignedInput() const {return true;}
	virtual void ProcessBlocks(byte *outString, const byte *inString, unsigned int numberOfBlocks) =0;
	void ResizeBuffers()
	{
		CipherModeBase::ResizeBuffers();
		m_buffer.New(BlockSize());
	}

	SecByteBlock m_buffer;
};

class CRYPTOPP_DLL ECB_OneWay : public BlockOrientedCipherModeBase
{
public:
	IV_Requirement IVRequirement() const {return NOT_RESYNCHRONIZABLE;}
	unsigned int OptimalBlockSize() const {return BlockSize() * m_cipher->OptimalNumberOfParallelBlocks();}
	void ProcessBlocks(byte *outString, const byte *inString, unsigned int numberOfBlocks)
		{m_cipher->ProcessAndXorMultipleBlocks(inString, NULL, outString, numberOfBlocks);}
};