idea.cpp

有关的IDEA的加解密算法

#include"idea.h"
static uint16 inv(uint16 x)
{
	uint16 t0,t1;
	uint16 q,y;
	if(x<=1)
		return x;
	t1=(uint16)(0x10001L/x);
	y=(uint16)(0x10001L%x);
	if(y==1)
		return low16(1-t1);
	t0=1;
	do
	{
		q=x/y;
		x=x%y;
		t0+=q*t1;
		if(x==1)
			return t0;
		q=y/x;
		y=y%x;
		t1+=q*t0;
	}while(y!=1);
	return low16(1-t1);
}
static void en_key_idea(word16 *userkey,word16 *Z)
{
	int i,j;
	                                          /*shifts*/
	for(j=0;j<8;j++)
		Z[j]=*userkey++;
	for(i=0;j<KEYLEN;j++)
	{
		i++;
		Z[i+7]=((Z[i&7]<<9)|(Z[(i+1 )& 7]>>7));
		Z+=i&8;
		i&=7;
	}
}
static void de_key_idea(IDEAkey Z,IDEAkey DK)
{
	int j;
	uint16 t1,t2,t3;
	IDEAkey T;
	word16 *p=T+KEYLEN;
	t1=inv(*Z++);
	t2=-*Z++;
	t3=-*Z++;
	*--p=inv(*Z++);
	*--p=t3;
	*--p=t2;
	*--p=t1;
	for(j=1;j<ROUNDS;j++)
	{
		t1=*Z++;
		*--p=*Z++;
		*--p=t1;
		t1=inv(*Z++);
		t2=-*Z++;
		t3=-*Z++;
		*--p=inv(*Z++);
		*--p=t2;
		*--p=t3;
		*--p=t1;
	}
	t1=*Z++;
	*--p=*Z++;
	*--p=t1;
    t1=inv(*Z++);
	t2=-*Z++;
	t3=-*Z++;
	*--p=inv(*Z++);
	*--p=t3;
	*--p=t2;
	*--p=t1;
	for(j=0,p=T;j<KEYLEN;j++)
	{
		*DK++=*p;
		*p++=0;
	}
}
uint16 mul(uint16 a,uint16 b)
{
	word32 p;
	if(a)
	{
		if(b)
		{
			p=(word32)a*b;
			b=(uint16)(low16(p));
			a=(uint16)(p>>16);
			return b-a+(b<a);
		}
		else
		{
			return 1-a;
		}
	}
	else return 1-b;
}


#define MUL(x,y) (x=mul(low16(x),y))
#define CONST
static void cipher_idea(word16 in[4],word16 out[4],register CONST IDEAkey Z)
{
	register uint16 x1,x2,x3,x4,t1,t2;
	int r=ROUNDS;                         /*运算*/
	x1=*in++;x2=*in++;
	x3=*in++;x4=*in;
	do
	{
		MUL(x1,*Z++);
		x2+=*Z++;
		x3+=*Z++;
		MUL(x4,*Z++);
		t2=x1^x3;
		MUL(t2,*Z++);
		t1=t2+(x2^x4);
		MUL(t1,*Z++);
		t2=t1+t2;
		x1^=t1;
		x4^=t2;
		t2^=x2;
		x2=x3^t1;
		x3=t2;
	}
	while(--r);
	MUL(x1,*Z++);
    *out++=x1;
	*out++=(x3+*Z++);
	*out++=(x2+*Z++);
	MUL(x4,*Z);
	*out=x4;
	}
char read_char_from_file(FILE*fp)
{
	char temp=0;
	if((fread(&temp,sizeof(char),1,fp))!=1)
		end_of_file=1;
	return temp;
}
word16 read_word16_from_file(FILE*fp)
{
	word16 temp=0;

	if((fread(&temp,sizeof(word16),1,fp))!=1)
	end_of_file=1;
	return temp;
}
void write_char_to_file(char data,FILE*fp)
{
	if((fwrite(&data,sizeof(char),1,fp))!=1)
	{
		printf("Fatal Error writing output file!!!\n");
		exit(-1);
	}
}
void write_word16_to_file(word16 data,FILE*fp)
{
	if((fwrite(&data,sizeof(word16),1,fp))!=1)
	{
		printf("Fatal Error writing output file!!!\n");
		exit(-1);
	}
}
void cipher_file(FILE*in,FILE*out,word16*key)
{
	word16 input[4],output[4];
	IDEAkey Z;
	int x,y;
	int count=0;
	long length;
	int temp;
	en_key_idea(key,Z);
	end_of_file=0;
	length=filelength(fileno(in));

	fwrite(&length,sizeof(long),1,out);
	while(! end_of_file)
	{
		x=0;
		while(x<4)
		{
			input[x]=((word16)(read_char_from_file(in)<<8));
			if(! end_of_file)
			{
				temp=read_char_from_file(in);
				if(temp<0) temp+=256;
				input[x]=input[x]|temp;
				x++;
			}
		
			if(end_of_file)
			{
				while(x<4) input[x++]=0;
				break;
			}
		}
		cipher_idea(input,output,Z);
		for(y=0;y<x;y++)
		{
			if(noisy) if(count++%256==0) printf(".");
			write_word16_to_file(output[y],out);
		}
	}
}
void decipher_file(FILE*in,FILE*out,word16*key)
{
	word16 input[4],output[4];
	int x,y;
	IDEAkey Z,DK;
	int count=0;
	long length=0;
	en_key_idea(key,Z);
	de_key_idea(Z,DK);
	end_of_file=0;

	fread(&length,sizeof(long),1,in);
 
	while(! end_of_file)
	{
		x=0;
		while(x<4)
		{
			input[x]=read_word16_from_file(in);
			if(end_of_file)
				break;
			x++;
		}
		
		cipher_idea(input,output,DK);
		
		for(y=0;y<x;y++)
		{

			if(noisy) if(count++%256==0) printf(".");
		    if(length-->0)
				write_char_to_file(((char)(output[y]>>8)),out);
	
			if(length-->0)
				write_char_to_file(((char)(output[y]&255)),out);
			
		
		}

	}
}
void swap_files_and_clean_up(char * file)
{
	long fsize ,count;
	FILE *fp;
	char temp[100];
	if (overwrite)
	{
		if((fp=fopen(file,"r+b"))==NULL)
		{
			printf("\n Error overwriting old file, security compromised.\n");
		}
		else
		{
			fseek(fp,01,SEEK_END);
			fsize=ftell(fp);
			fseek(fp,01,SEEK_SET);
			for(count=0;count<fsize;count++)
				fputc('0',fp);
			fclose(fp);
		}
		if((remove(file))!=0)
		{
			printf("\n ERROR removing old file <%s> \n",file);
			printf("encoded data remains in temporary file<%s> \n",tempfilename);
			exit(-1);
		}
	}
	else
	{
		strcpy(temp,file);
		file=strtok(temp,".");
		strcat(file,".enc");
	}
	if((rename(tempfilename,file))!=0)

	{
		printf("\n ERROR renaming temporary file<%s>!! \n",tempfilename);
		printf("Data is safely processed and stored in that file,\n");
		exit(-1);
	}
}

#define KBYTES 1024

void getuserkeyfromargv(word16 * key,char *arg)
{
	int x;
	for(x=0;x<strlen(arg)&&x<8;x++)
	{
		if(x==0)key[x]=arg[x]<<8;
		else key[x]=((arg[x]<<8|key[x-1]>>8));
	}
	if (strlen(arg)>8)printf("\n ONLY first * 8 * characters of key used!!! \n");
	if(x<8) while(x<8) key[x++]=0;
}

main(int argc , char * *argv)
{
	word16 userkey[8];
	char filename[100];
	FILE * fp,* temp;
	int to_or_from;
	noisy=1;
	overwrite=0;
	if(argc!=4)
	{
		printf("Usage: idea filename.ext[e|d[w]]key \n");
		printf("e=encode   d=decode   file \n");
		printf(" 64bit \n");
		exit(-1);
	}
	else
	{
		strncpy(filename,argv[1],99);
		filename[99]='\0';
		if (argv [2][0]=='e') to_or_from=1;
		else if(argv [2][0]=='d')to_or_from=0;
		else
		{
			printf("Usage: idea filename,ext[e]d[w]key \n");
			printf(" e=encrypt  d=decrypt w=overwrite file\n");
			printf(" 64 bit!!!\n");
			exit(-1);
		}
		if (argv[2][1]=='w')overwrite=1;
		getuserkeyfromargv(userkey,argv[3]);
	}
	if((fp=fopen(filename,"r+b"))==NULL)
	{
		printf("\n Error opening File %s\n",filename);
		exit(-1);
	}
	if((temp=fopen(tempfilename,"w+b"))==NULL)
	{
		printf("\n Erorr opening temporary file \n");
		exit(-1);
	}
	if(to_or_from==1)
	{
		printf("\n Encoding file %s   ",filename);
		cipher_file(fp,temp,userkey);
	}
	else
	{
		printf("\n Decoding file %s   ",filename);
		decipher_file (fp,temp,userkey);
	}
   
	fclose(fp);
	fclose(temp);
	swap_files_and_clean_up(filename);
	return 0;
}