sha.c

C语言实现的SHA-1报文摘要算法

/*
a C program for the "SHA-1"
Use "SHA-1" to compute the digest for the file "a.txt" in current directory 
created by yaolei
2005-4-13
*/
#include <stdio.h>


/*********************************Global var used to save the digest*/

/*state[0] = A, state[1] = B, state[2] = C, state[3] = D, state[4] = E*/
unsigned int state[5];


/*********************************Define the function used in SHA-1*/
unsigned int f1(unsigned int B, unsigned int C, unsigned int D)
{
	return (B&C)|(~B&D);
}

unsigned int f2(unsigned int B, unsigned int C, unsigned int D)
{
	return B^C^D;
}

unsigned int f3(unsigned int B, unsigned int C, unsigned int D)
{
	return (B&C)|(B&D)|(C&D);
}

unsigned int f4(unsigned int B, unsigned int C, unsigned int D)
{
	return B^C^D;
}


/*********************************Init the global var unsigned int state[5]*/
void Init()
{
	state[0] = 0x67452301;
	state[1] = 0xefcdab89;
	state[2] = 0x98badcfe;
	state[3] = 0x10325476;
	state[4] = 0xc3d2e1f0;
}
/*********************************the end of the function*/


/*********************************the function used to compute the 80 loops and save the result into the global var state[]*/
void shaTran(unsigned char * buf,unsigned int * state)
{
	int i,j;
	unsigned int A,B,C,D,E,temp;	/*the Register "A,B,C,D,E" and temp*/
	unsigned int K[4];		/*the K[t] used in SHA-1*/
	unsigned int W[80];		/*the W[t] used in SHA-1*/
	unsigned char * p = (unsigned char *)W;		/*the (unsigned char *)p point to W[0]*/

	/*********************************init the Register "A,B,C,D,E"*/
	A  = state[0];
	B  = state[1];
	C  = state[2];
	D  = state[3];
	E  = state[4];

	/*********************************init K*/
	
	K[0] = 0x5a827999;
	K[1] = 0x6ed9eba1;
	K[2] = 0x8f1bbcdc;
	K[3] = 0xca62c1d6;

	/*********************************compute W[t]*/
	
	/*compute W[t] 0<=t<=15*/
	/*++++++++++++++++++++++++++++++++
	Notice that
	The IA32 System use little-endian to save data in Main Memory
	So change the sequence before use it
	++++++++++++++++++++++++++++++++*/
	for(i=0;i<16;i++)
	{
		j = 4*i;
		p[j+3] = buf[j];
		p[j+2] = buf[j+1];
		p[j+1] = buf[j+2];
		p[j] = buf[j+3];
	}

	/*compute W[t] 16<=t<=79*/
	for(i=16;i<80;i++)
	{
		W[i] = ((W[i-16]^W[i-14]^W[i-8]^W[i-3])<<1) | ((W[i-16]^W[i-14]^W[i-8]^W[i-3])>>31);
	}


	/*********************************compute 1st loop*/
	for(i=0;i<20;i++)
	{
		temp = E + f1(B,C,D) + ((A<<5)|(A>>27)) + W[i] + K[0];
		E = D;
		D = C;
		C = (B<<30)|(B>>2);
		B = A;
		A = temp;
	}


	/*********************************compute 2nd loop*/
	for(i=20;i<40;i++)
	{
		temp = E + f2(B,C,D) + ((A<<5)|(A>>27)) + W[i] + K[1];
		E = D;
		D = C;
		C = (B<<30)|(B>>2);
		B = A;
		A = temp;
	}


	/*********************************compute 3rd loop*/
	for(i=40;i<60;i++)
	{
		temp = E + f3(B,C,D) + ((A<<5)|(A>>27)) + W[i] + K[2];
		E = D;
		D = C;
		C = (B<<30)|(B>>2);
		B = A;
		A = temp;
	}


	/*********************************compute 4th loop*/
	for(i=60;i<80;i++)
	{
		temp = E + f4(B,C,D) + ((A<<5)|(A>>27)) + W[i] + K[3];
		E = D;
		D = C;
		C = (B<<30)|(B>>2);
		B = A;
		A = temp;
	}


	/*********************************add the vars back into the global var state[]*/
	state[0] += A;
    state[1] += B;
    state[2] += C;
    state[3] += D;
    state[4] += E;
}
/*********************************the end of the function*/


/*********************************the function used to padding*/
void sha(unsigned char *buf, int len, unsigned int * state, unsigned int f1,unsigned int f2)
{
	int i;
	unsigned int floop1,floop2;		/*use floop1:floop2 to represent the length of the file in bit*/
	unsigned char flen[8];		/*use unsigned char flen[8] to transform the floop1:floop2 in last block*/
	unsigned char *p1 = (unsigned char *)&floop1;
	unsigned char *p2 = (unsigned char *)&floop2;
	floop1 = f1;
	floop2 = f2;
	floop2 = floop2 + (unsigned int)(len*8);	/*add the last block's length(in bit)*/


	/*********************************compute the whole file's length*/

	/*compute the length of the file and save it into unsigned char flen[8]*/
	/*++++++++++++++++++++++++++++++++
	Notice that
	The IA32 System use little-endian to save data in Main Memory
	So change the sequence before use it
	++++++++++++++++++++++++++++++++*/
	printf("floop1 = %08x\n",floop1);
	printf("floop2 = %08x\n",floop2);
	for(i=0; i<4; i++)
	{
		flen[3-i] = *p1;
		flen[7-i] = *p2;
		p1++;
		p2++;
	}

	
	/*********************************do the padding*/
	/*the file's length(bit) < 448 */
	if(len<56)
	{
		/*pad it like 1000000...(bit) from the end(buf[len-1]) to the buf[55]*/
		buf[len] = 0x80;
		for(i=len+1; i<56; i++)
		{
			buf[i] = 0x00;
		}

		/*pad the last 64bit using flen[8](the length of the file computed before)*/
		for(i=56; i<64; i++)
		{
			buf[i] = flen[i-56];
		}

		/*then call the function "shaTran" to do the loop*/
		shaTran(buf,state);
	}

	/*the file's length(bit) >= 448 */
	else
	{
		/*pad the 1st block with a number of bit 100000... until the end of the buf(buf[63])*/
		buf[len] = 0x80;
		for(i=len+1; i<64; i++)
		{
			buf[i] = 0x00;
		}

		/*call the function "shaTran" to do the loop*/
		shaTran(buf,state);

		/*pad the 1st block with a number of bit 000000... until the 448 bit(buf[55])*/
		for(i=0; i<56; i++)
			buf[i] = 0x00;

		/*pad the last 64bit using flen[8](the length of the file computed before)*/
		for(i=56; i<64; i++)
		{
			buf[i] = flen[i-56];
		}

		/*call the function "shaTran" to do the loop*/
		shaTran(buf,state);
	}
}
/*********************************the end of the function*/


int main()
{
	unsigned char buf[64];		/*the input block of SHA-1*/
	FILE * file;
	int len;		/*used to save the length of one read from the file (byte)*/
	unsigned int floop1,floop2;		/*use floop1:floop2 to represent the length of the file in bit*/
	floop1 = floop2 = 0;		/*at 1st make them equal 0*/
	
	/*********************************Init the global var*/
	Init();
	
	/*********************************can not open file error*/
	if (!(file = fopen("a.txt", "rb")))
	{
		printf("can not open file!!!\n");
		return -1;
	}

	/*********************************read data from the file*/
	while(!feof(file))
	{
		/*********************************each time read 64 bits into buf at most*/
		len=fread(buf,1,64,file);/*len used to save the length of each read*/
		
		/*********************************read file error*/
		if(ferror(file))
		{
			printf("read file error!!!\n");
			return -1;
		}
		

		/*********************************the buf[64] is full*/
		if(len == 64)
		{
			/*use 2 unsigned int to represent 1 64bit number, floop1:floop2*/
			if((floop1 == 0xffffffff) && (floop2 == 0xfffffe00))
			{
				printf("file larger than 2exp(64)");
				return -1;
			}
			if(floop2 != 0xfffffe00)floop2+=512;
			else
			{
				floop1++;
				floop2 = 0;
			}

		/*call the function "shaTran" to do the loop*/
		shaTran(buf,state);
		}

		/*********************************less than 512 bits need to pad*/
		else
		{
			/*call the function "sha" to do the padding and other compute*/
			sha(buf,len,state,floop1,floop2);
		}
	}
	

	/*********************************print the digest*/
	printf("%08x %08x %08x %08x %08x\n",state[0],state[1],state[2],state[3],state[4]);
	getchar();
	return 0;
}