path: root/seckey.h

// seckey.h - written and placed in the public domain by Wei Dai

// This file contains helper classes/functions for implementing secret key algorithms.

#ifndef CRYPTOPP_SECKEY_H
#define CRYPTOPP_SECKEY_H

#include "cryptlib.h"
#include "misc.h"
#include "simple.h"

NAMESPACE_BEGIN(CryptoPP)

inline CipherDir ReverseCipherDir(CipherDir dir)
{
	return (dir == ENCRYPTION) ? DECRYPTION : ENCRYPTION;
}

//! .
template <unsigned int N>
class FixedBlockSize
{
public:
	enum {BLOCKSIZE = N};
};

// ************** rounds ***************

//! .
template <unsigned int R>
class FixedRounds
{
public:
	enum {ROUNDS = R};

protected:
	template <class T>
	static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, unsigned int length, const NameValuePairs &param)
	{
		obj->ThrowIfInvalidKeyLength(length);
		int rounds = param.GetIntValueWithDefault("Rounds", ROUNDS);
		if (rounds != ROUNDS)
			throw InvalidRounds(obj->StaticAlgorithmName(), rounds);
		obj->UncheckedSetKey(dir, key, length);
	}
};

//! .
template <unsigned int D, unsigned int N=1, unsigned int M=INT_MAX>		// use INT_MAX here because enums are treated as signed ints
class VariableRounds
{
public:
	enum {DEFAULT_ROUNDS = D, MIN_ROUNDS = N, MAX_ROUNDS = M};
	static unsigned int StaticGetDefaultRounds(unsigned int keylength) {return DEFAULT_ROUNDS;}

protected:
	static inline void AssertValidRounds(unsigned int rounds)
	{
		assert(rounds >= MIN_ROUNDS && rounds <= MAX_ROUNDS);
	}

	template <class T>
	static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, unsigned int length, const NameValuePairs &param)
	{
		obj->ThrowIfInvalidKeyLength(length);
		int rounds = param.GetIntValueWithDefault("Rounds", obj->StaticGetDefaultRounds(length));
		if (rounds < (unsigned int)MIN_ROUNDS || rounds > (unsigned int)MAX_ROUNDS)
			throw InvalidRounds(obj->AlgorithmName(), rounds);
		obj->UncheckedSetKey(dir, key, length, rounds);
	}
};

// ************** key length ***************

//! .
template <unsigned int N, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE>
class FixedKeyLength
{
public:
	enum {KEYLENGTH=N, MIN_KEYLENGTH=N, MAX_KEYLENGTH=N, DEFAULT_KEYLENGTH=N};
	enum {IV_REQUIREMENT = IV_REQ};
	static unsigned int StaticGetValidKeyLength(unsigned int) {return KEYLENGTH;}
};

/// support query of variable key length, template parameters are default, min, max, multiple (default multiple 1)
template <unsigned int D, unsigned int N, unsigned int M, unsigned int Q = 1, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE>
class VariableKeyLength
{
	// make these private to avoid Doxygen documenting them in all derived classes
	CRYPTOPP_COMPILE_ASSERT(Q > 0);
	CRYPTOPP_COMPILE_ASSERT(N % Q == 0);
	CRYPTOPP_COMPILE_ASSERT(M % Q == 0);
	CRYPTOPP_COMPILE_ASSERT(N < M);
	CRYPTOPP_COMPILE_ASSERT(D >= N && M >= D);

public:
	enum {MIN_KEYLENGTH=N, MAX_KEYLENGTH=M, DEFAULT_KEYLENGTH=D, KEYLENGTH_MULTIPLE=Q};
	enum {IV_REQUIREMENT = IV_REQ};
	static unsigned int StaticGetValidKeyLength(unsigned int n)
	{
		if (n < (unsigned int)MIN_KEYLENGTH)
			return MIN_KEYLENGTH;
		else if (n > (unsigned int)MAX_KEYLENGTH)
			return MAX_KEYLENGTH;
		else
		{
			n += KEYLENGTH_MULTIPLE-1;
			return n - n%KEYLENGTH_MULTIPLE;
		}
	}
};

/// support query of key length that's the same as another class
template <class T>
class SameKeyLengthAs
{
public:
	enum {MIN_KEYLENGTH=T::MIN_KEYLENGTH, MAX_KEYLENGTH=T::MAX_KEYLENGTH, DEFAULT_KEYLENGTH=T::DEFAULT_KEYLENGTH};
	enum {IV_REQUIREMENT = T::IV_REQUIREMENT};
	static unsigned int StaticGetValidKeyLength(unsigned int keylength)
		{return T::StaticGetValidKeyLength(keylength);}
};

// ************** implementation helper for SimpledKeyed ***************

template <class T>
static inline void CheckedSetKey(T *obj, Empty empty, const byte *key, unsigned int length, const NameValuePairs &param)
{
	obj->ThrowIfInvalidKeyLength(length);
	obj->UncheckedSetKey(key, length);
}

template <class T>
static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, unsigned int length, const NameValuePairs &param)
{
	obj->ThrowIfInvalidKeyLength(length);
	obj->UncheckedSetKey(dir, key, length);
}

//! .
template <class BASE, class INFO = BASE>
class SimpleKeyingInterfaceImpl : public BASE
{
public:
	unsigned int MinKeyLength() const {return INFO::MIN_KEYLENGTH;}
	unsigned int MaxKeyLength() const {return INFO::MAX_KEYLENGTH;}
	unsigned int DefaultKeyLength() const {return INFO::DEFAULT_KEYLENGTH;}
	unsigned int GetValidKeyLength(unsigned int n) const {return INFO::StaticGetValidKeyLength(n);}
	typename BASE::IV_Requirement IVRequirement() const {return (typename BASE::IV_Requirement)INFO::IV_REQUIREMENT;}

protected:
	void AssertValidKeyLength(unsigned int length) {assert(GetValidKeyLength(length) == length);}
};

template <class INFO, class INTERFACE = BlockCipher>
class BlockCipherBaseTemplate : public AlgorithmImpl<SimpleKeyingInterfaceImpl<TwoBases<INFO, INTERFACE> > >
{
public:
	unsigned int BlockSize() const {return BLOCKSIZE;}
};

//! .
template <CipherDir DIR, class BASE>
class BlockCipherTemplate : public BASE
{
public:
 	BlockCipherTemplate() {}
	BlockCipherTemplate(const byte *key)
		{SetKey(key, DEFAULT_KEYLENGTH);}
	BlockCipherTemplate(const byte *key, unsigned int length)
		{SetKey(key, length);}
	BlockCipherTemplate(const byte *key, unsigned int length, unsigned int rounds)
		{SetKeyWithRounds(key, length, rounds);}

	bool IsForwardTransformation() const {return DIR == ENCRYPTION;}

	void SetKey(const byte *key, unsigned int length, const NameValuePairs &param = g_nullNameValuePairs)
	{
		CheckedSetKey(this, DIR, key, length, param);
	}

	Clonable * Clone() {return new BlockCipherTemplate<DIR, BASE>(*this);}
};

//! .
template <class BASE>
class MessageAuthenticationCodeTemplate : public 
#ifdef CRYPTOPP_DOXYGEN_PROCESSING
	MessageAuthenticationCode
#else
	SimpleKeyingInterfaceImpl<BASE>
#endif
{
public:
 	MessageAuthenticationCodeTemplate() {}
	MessageAuthenticationCodeTemplate(const byte *key)
		{SetKey(key, DEFAULT_KEYLENGTH);}
	MessageAuthenticationCodeTemplate(const byte *key, unsigned int length)
		{SetKey(key, length);}

	std::string AlgorithmName() const {return StaticAlgorithmName();}

	void SetKey(const byte *key, unsigned int length, const NameValuePairs &param = g_nullNameValuePairs)
	{
		CheckedSetKey(this, Empty(), key, length, param);
	}

	Clonable * Clone() {return new MessageAuthenticationCodeTemplate<BASE>(*this);}
};

// ************** documentation ***************

//! These objects usually should not be used directly. See CipherModeDocumentation instead.
/*! Each class derived from this one defines two types, Encryption and Decryption, 
	both of which implement the BlockCipher interface. */
struct BlockCipherDocumentation
{
	//! implements the BlockCipher interface
	typedef BlockCipher Encryption;
	//! implements the BlockCipher interface
	typedef BlockCipher Decryption;
};

/*! \brief Each class derived from this one defines two types, Encryption and Decryption, 
	both of which implement the SymmetricCipher interface. See CipherModeDocumentation
	for information about using block ciphers. */
struct SymmetricCipherDocumentation
{
	//! implements the SymmetricCipher interface
	typedef SymmetricCipher Encryption;
	//! implements the SymmetricCipher interface
	typedef SymmetricCipher Decryption;
};

NAMESPACE_END

#endif