sha1.cpp

SHA1算法软件程序实现

/*
 *	sha1.cpp
 *
 *	Copyright (C) 1998
 *	Paul E. Jones <[e-mail]>
 *	All Rights Reserved.
 *
 *****************************************************************************
 *	$Id: sha1.cpp,v 1.9 2004/03/27 18:02:20 paulej Exp $
 *****************************************************************************
 *
 *	Description:
 * 		This class implements the Secure Hashing Standard as defined
 * 		in FIPS PUB 180-1 published April 17, 1995.
 *
 * 		The Secure Hashing Standard, which uses the Secure Hashing
 * 		Algorithm (SHA), produces a 160-bit message digest for a
 * 		given data stream.  In theory, it is highly improbable that
 * 		two messages will produce the same message digest.  Therefore,
 * 		this algorithm can serve as a means of providing a "fingerprint"
 * 		for a message.
 *
 *	Portability Issues:
 * 		SHA-1 is defined in terms of 32-bit "words".  This code was
 * 		written with the expectation that the processor has at least
 * 		a 32-bit machine word size.  If the machine word size is larger,
 * 		the code should still function properly.  One caveat to that
 *		is that the input functions taking characters and character arrays
 *		assume that only 8 bits of information are stored in each character.
 *
 *	Caveats:
 * 		SHA-1 is designed to work with messages less than 2^64 bits long.
 * 		Although SHA-1 allows a message digest to be generated for
 * 		messages of any number of bits less than 2^64, this implementation
 * 		only works with messages with a length that is a multiple of 8
 * 		bits.
 *
 */


#include "sha1.h"

SHA1::SHA1()
{
	SHAInit();
}

SHA1::~SHA1()
{
}

void SHA1::SHAInit()
{
	Length_Low				= 0;
	Length_High			= 0;
	Message_Block_Index	= 0;

	H[0]		= 0x67452301;
	H[1]		= 0xEFCDAB89;
	H[2]		= 0x98BADCFE;
	H[3]		= 0x10325476;
	H[4]		= 0xC3D2E1F0;
}

// space of lpSHACode_Output must be >= 20 bytes;
bool SHA1::SHA_GO( const char *lpData_Input, char *lpSHACode_Output )
{
	if (lpData_Input == NULL || lpSHACode_Output == NULL)
		return false;

	SHAInit();

	// One times analyse 64Bytes, 512 bits.
	int nInputLen = strlen(lpData_Input);
	int nDealDataLen = 0;							//	the length of can-deal-data, this times;
	for(int pos=0 ; pos<=nInputLen ; pos+=64)
	{
		if (nInputLen - pos >= 64)
		{
			nDealDataLen = 64;						// input-data is enough fill 64bytes,
			memset(Message_Block, 0, sizeof(Message_Block));
			memcpy(Message_Block, lpData_Input + pos, nDealDataLen);

			AddDataLen(nDealDataLen);
			ProcessMessageBlock();
			AddDataLen(0);
		}
		else
		{
			nDealDataLen = nInputLen - pos;			//	input-data isn't enough fill 64bytes,need fill 0x8000000000 and lenth of real-data.
			memset(Message_Block, 0, sizeof(Message_Block));
			memcpy(Message_Block, lpData_Input + pos, nDealDataLen);

			AddDataLen(nDealDataLen);
			PadMessage();
		}
	}

	// copy result to output
	for (int i = 0; i < 5; i++)
	{
		sprintf(&(lpSHACode_Output[8*i]),"%08x", H[i]);
	}

	return true;
}

void SHA1::AddDataLen(int nDealDataLen)
{
	Message_Block_Index = nDealDataLen;

	if ((Length_Low += ((unsigned int)nDealDataLen << 3)) < ((unsigned int)nDealDataLen << 3))
	{
		Length_High++;
	}
	Length_High += ((unsigned int)nDealDataLen >> 29);
}


/*
 *	ProcessMessageBlock
 *
 *	Description:
 *		This function will process the next 512 bits of the message
 *		stored in the Message_Block array.
 *
 *	Parameters:
 *		None.
 *
 *	Returns:
 *		Nothing.
 *
 *	Comments:
 *		Many of the variable names in this function, especially the single
 *	 	character names, were used because those were the names used
 *	  	in the publication.
 *
 */
void SHA1::ProcessMessageBlock()
{
	const unsigned K[] = 	{ 				// Constants defined for SHA-1
								0x5A827999,
								0x6ED9EBA1,
								0x8F1BBCDC,
								0xCA62C1D6
							};
	int 		t;							// Loop counter
	unsigned 	temp;						// Temporary word value
	unsigned	W[80];						// Word sequence
	unsigned	A, B, C, D, E;				// Word buffers

	/*
	 *	Initialize the first 16 words in the array W
	 */
	for(t = 0; t < 16; t++)
	{
		W[t] = ((unsigned) Message_Block[t * 4]) << 24;
		W[t] |= ((unsigned) Message_Block[t * 4 + 1]) << 16;
		W[t] |= ((unsigned) Message_Block[t * 4 + 2]) << 8;
		W[t] |= ((unsigned) Message_Block[t * 4 + 3]);
	}

	for(t = 16; t < 80; t++)
	{
	   W[t] = CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
	}

	A = H[0];
	B = H[1];
	C = H[2];
	D = H[3];
	E = H[4];

	for(t = 0; t < 20; t++)
	{
		temp = CircularShift(5,A) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}

	for(t = 20; t < 40; t++)
	{
		temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}

	for(t = 40; t < 60; t++)
	{
		temp = CircularShift(5,A) +
		 	   ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}

	for(t = 60; t < 80; t++)
	{
		temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}

	H[0] = (H[0] + A) & 0xFFFFFFFF;
	H[1] = (H[1] + B) & 0xFFFFFFFF;
	H[2] = (H[2] + C) & 0xFFFFFFFF;
	H[3] = (H[3] + D) & 0xFFFFFFFF;
	H[4] = (H[4] + E) & 0xFFFFFFFF;
}

/*
 *	PadMessage
 *
 *	Description:
 *		According to the standard, the message must be padded to an even
 *		512 bits.  The first padding bit must be a '1'.  The last 64 bits
 *		represent the length of the original message.  All bits in between
 *		should be 0.  This function will pad the message according to those
 *		rules by filling the message_block array accordingly.  It will also
 *		call ProcessMessageBlock() appropriately.  When it returns, it
 *		can be assumed that the message digest has been computed.
 *
 *	Parameters:
 *		None.
 *
 *	Returns:
 *		Nothing.
 *
 *	Comments:
 *
 */
void SHA1::PadMessage()
{
	/*
	 *	Check to see if the current message block is too small to hold
	 *	the initial padding bits and length.  If so, we will pad the
	 *	block, process it, and then continue padding into a second block.
	 */
	if (Message_Block_Index > 55)
	{
		Message_Block[Message_Block_Index++] = 0x80;
		while(Message_Block_Index < 64)
		{
			Message_Block[Message_Block_Index++] = 0;
		}

		ProcessMessageBlock();

		while(Message_Block_Index < 56)
		{
			Message_Block[Message_Block_Index++] = 0;
		}
	}
	else
	{
		Message_Block[Message_Block_Index++] = 0x80;
		while(Message_Block_Index < 56)
		{
			Message_Block[Message_Block_Index++] = 0;
		}

	}

	/*
	 *	Store the message length as the last 8 octets
	 */
	Message_Block[56] = (Length_High >> 24) & 0xFF;
	Message_Block[57] = (Length_High >> 16) & 0xFF;
	Message_Block[58] = (Length_High >> 8) & 0xFF;
	Message_Block[59] = (Length_High) & 0xFF;
	Message_Block[60] = (Length_Low >> 24) & 0xFF;
	Message_Block[61] = (Length_Low >> 16) & 0xFF;
	Message_Block[62] = (Length_Low >> 8) & 0xFF;
	Message_Block[63] = (Length_Low) & 0xFF;

	ProcessMessageBlock();
}


/*
 *	CircularShift
 *
 *	Description:
 *		This member function will perform a circular shifting operation.
 *
 *	Parameters:
 *		bits: [in]
 *			The number of bits to shift (1-31)
 *		word: [in]
 *			The value to shift (assumes a 32-bit integer)
 *
 *	Returns:
 *		The shifted value.
 *
 *	Comments:
 *
 */
unsigned SHA1::CircularShift(int bits, unsigned word)
{
	return ((word << bits) & 0xFFFFFFFF) | ((word & 0xFFFFFFFF) >> (32-bits));
}