cryptlib.h

这是密码学数字签名算法的代码

		attachment chain is deleted when the anchor object is destructed.
	*/
	//@{
		//! returns whether this object allows attachment
		virtual bool Attachable() {return false;}
		//! returns the object immediately attached to this object or NULL for no attachment
		virtual BufferedTransformation *AttachedTransformation() {assert(!Attachable()); return 0;}
		//!
		virtual const BufferedTransformation *AttachedTransformation() const
			{return const_cast<BufferedTransformation *>(this)->AttachedTransformation();}
		//! delete the current attachment chain and replace it with newAttachment
		virtual void Detach(BufferedTransformation *newAttachment = 0)
			{assert(!Attachable()); throw NotImplemented("BufferedTransformation: this object is not attachable");}
		//! add newAttachment to the end of attachment chain
		virtual void Attach(BufferedTransformation *newAttachment);
	//@}

protected:
	static int DecrementPropagation(int propagation)
		{return propagation != 0 ? propagation - 1 : 0;}
};

//! returns a reference to a BufferedTransformation object that discards all input
BufferedTransformation & TheBitBucket();

//! interface for crypto material, such as public and private keys, and crypto parameters

class CryptoMaterial : public NameValuePairs
{
public:
	//! exception thrown when invalid crypto material is detected
	class InvalidMaterial : public InvalidDataFormat
	{
	public:
		explicit InvalidMaterial(const std::string &s) : InvalidDataFormat(s) {}
	};

	//! assign values from source to this object
	/*! \note This function can be used to create a public key from a private key. */
	virtual void AssignFrom(const NameValuePairs &source) =0;

	//! check this object for errors
	/*! \param level denotes the level of thoroughness:
		0 - using this object won't cause a crash or exception (rng is ignored)
		1 - this object will probably function (encrypt, sign, etc.) correctly (but may not check for weak keys and such)
		2 - make sure this object will function correctly, and do reasonable security checks
		3 - do checks that may take a long time
		\return true if the tests pass */
	virtual bool Validate(RandomNumberGenerator &rng, unsigned int level) const =0;

	//! throws InvalidMaterial if this object fails Validate() test
	virtual void ThrowIfInvalid(RandomNumberGenerator &rng, unsigned int level) const
		{if (!Validate(rng, level)) throw InvalidMaterial("CryptoMaterial: this object contains invalid values");}

//	virtual std::vector<std::string> GetSupportedFormats(bool includeSaveOnly=false, bool includeLoadOnly=false);

	//! save key into a BufferedTransformation
	virtual void Save(BufferedTransformation &bt) const
		{throw NotImplemented("CryptoMaterial: this object does not support saving");}

	//! load key from a BufferedTransformation
	/*! \throws KeyingErr if decode fails
		\note Generally does not check that the key is valid.
			Call ValidateKey() or ThrowIfInvalidKey() to check that. */
	virtual void Load(BufferedTransformation &bt)
		{throw NotImplemented("CryptoMaterial: this object does not support loading");}

	//! \return whether this object supports precomputation
	virtual bool SupportsPrecomputation() const {return false;}
	//! do precomputation
	/*! The exact semantics of Precompute() is varies, but
		typically it means calculate a table of n objects
		that can be used later to speed up computation. */
	virtual void Precompute(unsigned int n)
		{assert(!SupportsPrecomputation()); throw NotImplemented("CryptoMaterial: this object does not support precomputation");}
	//! retrieve previously saved precomputation
	virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
		{assert(!SupportsPrecomputation()); throw NotImplemented("CryptoMaterial: this object does not support precomputation");}
	//! save precomputation for later use
	virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
		{assert(!SupportsPrecomputation()); throw NotImplemented("CryptoMaterial: this object does not support precomputation");}

	// for internal library use
	void DoQuickSanityCheck() const	{ThrowIfInvalid(NullRNG(), 0);}
};

//! interface for generatable crypto material, such as private keys and crypto parameters

class GeneratableCryptoMaterial : virtual public CryptoMaterial
{
public:
	//! generate a random key or crypto parameters
	/*! \throws KeyingErr if algorithm parameters are invalid, or if a key can't be generated
		(e.g., if this is a public key object) */
	virtual void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &params = g_nullNameValuePairs)
		{throw NotImplemented("GeneratableCryptoMaterial: this object does not support key/parameter generation");}

	//! calls the above function with a NameValuePairs object that just specifies "KeySize"
	void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize);
};

//! interface for public keys

class PublicKey : virtual public CryptoMaterial
{
};

//! interface for private keys

class PrivateKey : public GeneratableCryptoMaterial
{
};

//! interface for crypto prameters

class CryptoParameters : public GeneratableCryptoMaterial
{
};

//! interface for asymmetric algorithms

class AsymmetricAlgorithm : public Algorithm
{
public:
	//! returns a reference to the crypto material used by this object
	virtual CryptoMaterial & AccessMaterial() =0;
	//! returns a const reference to the crypto material used by this object
	virtual const CryptoMaterial & GetMaterial() const =0;

	//! for backwards compatibility, calls AccessMaterial().Load(bt)
	void BERDecode(BufferedTransformation &bt)
		{AccessMaterial().Load(bt);}
	//! for backwards compatibility, calls GetMaterial().Save(bt)
	void DEREncode(BufferedTransformation &bt) const
		{GetMaterial().Save(bt);}
};

//! interface for asymmetric algorithms using public keys

class PublicKeyAlgorithm : public AsymmetricAlgorithm
{
public:
	// VC60 workaround: no co-variant return type
	CryptoMaterial & AccessMaterial() {return AccessPublicKey();}
	const CryptoMaterial & GetMaterial() const {return GetPublicKey();}

	virtual PublicKey & AccessPublicKey() =0;
	virtual const PublicKey & GetPublicKey() const {return const_cast<PublicKeyAlgorithm *>(this)->AccessPublicKey();}
};

//! interface for asymmetric algorithms using private keys

class PrivateKeyAlgorithm : public AsymmetricAlgorithm
{
public:
	CryptoMaterial & AccessMaterial() {return AccessPrivateKey();}
	const CryptoMaterial & GetMaterial() const {return GetPrivateKey();}

	virtual PrivateKey & AccessPrivateKey() =0;
	virtual const PrivateKey & GetPrivateKey() const {return const_cast<PrivateKeyAlgorithm *>(this)->AccessPrivateKey();}
};

//! interface for key agreement algorithms

class KeyAgreementAlgorithm : public AsymmetricAlgorithm
{
public:
	CryptoMaterial & AccessMaterial() {return AccessCryptoParameters();}
	const CryptoMaterial & GetMaterial() const {return GetCryptoParameters();}

	virtual CryptoParameters & AccessCryptoParameters() =0;
	virtual const CryptoParameters & GetCryptoParameters() const {return const_cast<KeyAgreementAlgorithm *>(this)->AccessCryptoParameters();}
};

//! interface for public-key encryptors and decryptors

/*! This class provides an interface common to encryptors and decryptors
	for querying their plaintext and ciphertext lengths.
*/
class PK_CryptoSystem
{
public:
	virtual ~PK_CryptoSystem() {}

	//! maximum length of plaintext for a given ciphertext length
	/*! \note This function returns 0 if cipherTextLength is not valid (too long or too short). */
	virtual unsigned int MaxPlaintextLength(unsigned int cipherTextLength) const =0;

	//! calculate length of ciphertext given length of plaintext
	/*! \note This function returns 0 if plainTextLength is not valid (too long). */
	virtual unsigned int CiphertextLength(unsigned int plainTextLength) const =0;

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	unsigned int MaxPlainTextLength(unsigned int cipherTextLength) const {return MaxPlaintextLength(cipherTextLength);}
	unsigned int CipherTextLength(unsigned int plainTextLength) const {return CiphertextLength(plainTextLength);}
#endif
};

//! interface for public-key encryptors

class PK_Encryptor : virtual public PK_CryptoSystem, public PublicKeyAlgorithm
{
public:
	//! .
	class InvalidPlaintextLength : public Exception
	{
	public:
		InvalidPlaintextLength() : Exception(OTHER_ERROR, "PK_Encryptor: invalid plaintext length") {}
	};

	//! encrypt a byte string
	/*! \pre CipherTextLength(plainTextLength) != 0 (i.e., plainText isn't too long)
		\pre size of cipherText == CipherTextLength(plainTextLength)
	*/
	virtual void Encrypt(RandomNumberGenerator &rng, const byte *plainText, unsigned int plainTextLength, byte *cipherText) const =0;

	//! create a new encryption filter
	/*! \note caller is responsible for deleting the returned pointer
	*/
	virtual BufferedTransformation * CreateEncryptionFilter(RandomNumberGenerator &rng, BufferedTransformation *attachment=NULL) const;
};

//! interface for public-key decryptors

class PK_Decryptor : virtual public PK_CryptoSystem, public PrivateKeyAlgorithm
{
public:
	//! decrypt a byte string, and return the length of plaintext
	/*! \pre size of plainText == MaxPlainTextLength(cipherTextLength) bytes.
		\return the actual length of the plaintext, or 0 if decryption fails.
	*/
	virtual DecodingResult Decrypt(const byte *cipherText, unsigned int cipherTextLength, byte *plainText) const =0;

	//! create a new decryption filter
	/*! \note caller is responsible for deleting the returned pointer
	*/
	virtual BufferedTransformation * CreateDecryptionFilter(BufferedTransformation *attachment=NULL) const;
};

//! interface for encryptors and decryptors with fixed length ciphertext

/*! A simplified interface is provided for crypto systems (such
	as RSA) whose ciphertext length and maximum plaintext length
	depend only on the key.
*/
class PK_FixedLengthCryptoSystem : virtual public PK_CryptoSystem
{
public:
	//!
	virtual unsigned int FixedMaxPlaintextLength() const =0;
	//!
	virtual unsigned int FixedCiphertextLength() const =0;

	unsigned int MaxPlaintextLength(unsigned int cipherTextLength) const;
	unsigned int CiphertextLength(unsigned int plainTextLength) const;
	
#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	unsigned int MaxPlainTextLength(unsigned int cipherTextLength) const {return MaxPlaintextLength(cipherTextLength);}
	unsigned int CipherTextLength(unsigned int plainTextLength) const {return CiphertextLength(plainTextLength);}
	unsigned int MaxPlainTextLength() const {return FixedMaxPlaintextLength();}
	unsigned int CipherTextLength() const {return FixedCiphertextLength();}
#endif
};

//! interface for encryptors with fixed length ciphertext

class PK_FixedLengthEncryptor : public PK_Encryptor, virtual public PK_FixedLengthCryptoSystem
{
};

//! interface for decryptors with fixed length ciphertext

class PK_FixedLengthDecryptor : public PK_Decryptor, virtual public PK_FixedLengthCryptoSystem
{
public:
	//! decrypt a byte string, and return the length of plaintext
	/*! \pre length of cipherText == CipherTextLength()
		\pre size of plainText == MaxPlainTextLength()
		\return the actual length of the plaintext, or 0 if decryption fails.
	*/
	virtual DecodingResult FixedLengthDecrypt(const byte *cipherText, byte *plainText) const =0;

	DecodingResult Decrypt(const byte *cipherText, unsigned int cipherTextLength, byte *plainText) const;

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	DecodingResult Decrypt(const byte *cipherText, byte *plainText) const {return FixedLengthDecrypt(cipherText, plainText);}
#endif
};

//! interface for public-key signers and verifiers

/*! This class provides an interface common to signers and verifiers
	for querying their signature lengths and creating message
	accumulators.
*/
class PK_SignatureScheme
{
public:
	virtual ~PK_SignatureScheme() {}