integer.h

用C做的

#ifndef CRYPTOPP_INTEGER_H
#define CRYPTOPP_INTEGER_H

/** \file */

#include "cryptlib.h"
#include "secblock.h"

#include <iosfwd>
#include <algorithm>

#ifdef CRYPTOPP_X86ASM_AVAILABLE

#ifdef _M_IX86
	#if (defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 500)) || (defined(__ICL) && (__ICL >= 500))
		#define SSE2_INTRINSICS_AVAILABLE
		#define CRYPTOPP_MM_MALLOC_AVAILABLE
	#elif defined(_MSC_VER)
		// _mm_free seems to be the only way to tell if the Processor Pack is installed or not
		#include <malloc.h>
		#if defined(_mm_free)
			#define SSE2_INTRINSICS_AVAILABLE
			#define CRYPTOPP_MM_MALLOC_AVAILABLE
		#endif
	#endif
#endif

// SSE2 intrinsics work in GCC 3.3 or later
#if defined(__SSE2__) && (__GNUC__ > 3 || __GNUC_MINOR__ > 2)
	#define SSE2_INTRINSICS_AVAILABLE
#endif

#endif

NAMESPACE_BEGIN(CryptoPP)

#if defined(SSE2_INTRINSICS_AVAILABLE)
	template <class T>
	class AlignedAllocator : public AllocatorBase<T>
	{
	public:
		CRYPTOPP_INHERIT_ALLOCATOR_TYPES

		pointer allocate(size_type n, const void *);
		void deallocate(void *p, size_type n);
		pointer reallocate(T *p, size_type oldSize, size_type newSize, bool preserve)
		{
			return StandardReallocate(*this, p, oldSize, newSize, preserve);
		}

	#if !(defined(CRYPTOPP_MALLOC_ALIGNMENT_IS_16) || defined(CRYPTOPP_MEMALIGN_AVAILABLE) || defined(CRYPTOPP_MM_MALLOC_AVAILABLE))
	#define CRYPTOPP_NO_ALIGNED_ALLOC
		AlignedAllocator() : m_pBlock(NULL) {}
	protected:
		void *m_pBlock;
	#endif
	};

	#ifdef CRYPTOPP_IMPORTS
		CRYPTOPP_DLL_TEMPLATE_CLASS AlignedAllocator<word>;
	#endif

	typedef SecBlock<word, AlignedAllocator<word> > SecAlignedWordBlock;
#else
	typedef SecWordBlock SecAlignedWordBlock;
#endif

void CRYPTOPP_DLL CRYPTOPP_API DisableSSE2();

struct InitializeInteger	// used to initialize static variables
{
	InitializeInteger();
};

//! multiple precision integer and basic arithmetics
/*! This class can represent positive and negative integers
	with absolute value less than (256**sizeof(word)) ** (256**sizeof(int)).
	\nosubgrouping
*/
class CRYPTOPP_DLL Integer : private InitializeInteger, public ASN1Object
{
public:
	//! \name ENUMS, EXCEPTIONS, and TYPEDEFS
	//@{
		//! division by zero exception
		class DivideByZero : public Exception
		{
		public:
			DivideByZero() : Exception(OTHER_ERROR, "Integer: division by zero") {}
		};

		//!
		class RandomNumberNotFound : public Exception
		{
		public:
			RandomNumberNotFound() : Exception(OTHER_ERROR, "Integer: no integer satisfies the given parameters") {}
		};

		//!
		enum Sign {POSITIVE=0, NEGATIVE=1};

		//!
		enum Signedness {
		//!
			UNSIGNED,
		//!
			SIGNED};

		//!
		enum RandomNumberType {
		//!
			ANY,
		//!
			PRIME};
	//@}

	//! \name CREATORS
	//@{
		//! creates the zero integer
		Integer();

		//! copy constructor
		Integer(const Integer& t);

		//! convert from signed long
		Integer(signed long value);

		//! convert from lword
		Integer(Sign s, lword value);

		//! convert from two words
		Integer(Sign s, word highWord, word lowWord);

		//! convert from string
		/*! str can be in base 2, 8, 10, or 16.  Base is determined by a
			case insensitive suffix of 'h', 'o', or 'b'.  No suffix means base 10.
		*/
		explicit Integer(const char *str);
		explicit Integer(const wchar_t *str);

		//! convert from big-endian byte array
		Integer(const byte *encodedInteger, size_t byteCount, Signedness s=UNSIGNED);

		//! convert from big-endian form stored in a BufferedTransformation
		Integer(BufferedTransformation &bt, size_t byteCount, Signedness s=UNSIGNED);

		//! convert from BER encoded byte array stored in a BufferedTransformation object
		explicit Integer(BufferedTransformation &bt);

		//! create a random integer
		/*! The random integer created is uniformly distributed over [0, 2**bitcount). */
		Integer(RandomNumberGenerator &rng, size_t bitcount);

		//! avoid calling constructors for these frequently used integers
		static const Integer & CRYPTOPP_API Zero();
		//! avoid calling constructors for these frequently used integers
		static const Integer & CRYPTOPP_API One();
		//! avoid calling constructors for these frequently used integers
		static const Integer & CRYPTOPP_API Two();

		//! create a random integer of special type
		/*! Ideally, the random integer created should be uniformly distributed
			over {x | min <= x <= max and x is of rnType and x % mod == equiv}.
			However the actual distribution may not be uniform because sequential
			search is used to find an appropriate number from a random starting
			point.
			May return (with very small probability) a pseudoprime when a prime
			is requested and max > lastSmallPrime*lastSmallPrime (lastSmallPrime
			is declared in nbtheory.h).
			\throw RandomNumberNotFound if the set is empty.
		*/
		Integer(RandomNumberGenerator &rng, const Integer &min, const Integer &max, RandomNumberType rnType=ANY, const Integer &equiv=Zero(), const Integer &mod=One());

		//! return the integer 2**e
		static Integer CRYPTOPP_API Power2(size_t e);
	//@}

	//! \name ENCODE/DECODE
	//@{
		//! minimum number of bytes to encode this integer
		/*! MinEncodedSize of 0 is 1 */
		size_t MinEncodedSize(Signedness=UNSIGNED) const;
		//! encode in big-endian format
		/*! unsigned means encode absolute value, signed means encode two's complement if negative.
			if outputLen < MinEncodedSize, the most significant bytes will be dropped
			if outputLen > MinEncodedSize, the most significant bytes will be padded
		*/
		void Encode(byte *output, size_t outputLen, Signedness=UNSIGNED) const;
		//!
		void Encode(BufferedTransformation &bt, size_t outputLen, Signedness=UNSIGNED) const;

		//! encode using Distinguished Encoding Rules, put result into a BufferedTransformation object
		void DEREncode(BufferedTransformation &bt) const;

		//! encode absolute value as big-endian octet string
		void DEREncodeAsOctetString(BufferedTransformation &bt, size_t length) const;

		//! encode absolute value in OpenPGP format, return length of output
		size_t OpenPGPEncode(byte *output, size_t bufferSize) const;
		//! encode absolute value in OpenPGP format, put result into a BufferedTransformation object
		size_t OpenPGPEncode(BufferedTransformation &bt) const;

		//!
		void Decode(const byte *input, size_t inputLen, Signedness=UNSIGNED);
		//! 
		//* Precondition: bt.MaxRetrievable() >= inputLen
		void Decode(BufferedTransformation &bt, size_t inputLen, Signedness=UNSIGNED);

		//!
		void BERDecode(const byte *input, size_t inputLen);
		//!
		void BERDecode(BufferedTransformation &bt);

		//! decode nonnegative value as big-endian octet string
		void BERDecodeAsOctetString(BufferedTransformation &bt, size_t length);

		class OpenPGPDecodeErr : public Exception
		{
		public: 
			OpenPGPDecodeErr() : Exception(INVALID_DATA_FORMAT, "OpenPGP decode error") {}
		};

		//!
		void OpenPGPDecode(const byte *input, size_t inputLen);
		//!
		void OpenPGPDecode(BufferedTransformation &bt);
	//@}

	//! \name ACCESSORS
	//@{
		//! return true if *this can be represented as a signed long
		bool IsConvertableToLong() const;
		//! return equivalent signed long if possible, otherwise undefined
		signed long ConvertToLong() const;

		//! number of significant bits = floor(log2(abs(*this))) + 1
		unsigned int BitCount() const;