#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
char a;
void perr(char *);
int *sign();
char filename[100];
char newfile[100];
char skfile[100];
static char x[20];
int cmp();
int *tz();
int *sub();
int *multi();
int *chu();
int *mn();
FILE *fp;
FILE *nfp;
FILE *kfp;
 char n[20];
unsigned long k;
main(argc,argv)
int argc; char **argv;
{unsigned long block=0;
int *x;
char x2[20];
 long num=0,p,i=0;
 char a,ch;
 int r,j;
 printf("Do you like to sign your file ?(Y/N):");
 gets(&a);
 if (a=='N'||a=='n') exit(1);
 if(argc>3||argc==2) perr("Usage: signing [filename] [skfile]");
 if(argc==3) {strcpy(filename,argv[1]);strcpy(skfile,argv[2]);}
 else
 {
 printf("\nEnter the filename needing signing: ");gets(filename);
 printf("\nEnter your skfile: ");gets(skfile);
 }
 strcpy(newfile,filename);
 while(newfile[i]!='\0')
 {i=i+1;}
 ch=newfile[i-1];
 newfile[i-1]='#';
 if((fp=fopen(filename,"r"))==NULL) perr("Can't open file!");
 if((kfp=fopen(skfile,"r"))==NULL) perr("Can't open file!");
 if((nfp=fopen(newfile,"w+"))==NULL) perr("Can't creat new file!");

 fscanf(kfp,"%s\n%u",n,&k);
 printf("n=%s\nsk=%u",n,k);
 fclose(kfp);
 fputc(ch,nfp);
 while((fgetc(fp))!=EOF)
  {num++;}printf("mum=%u",num);

 fprintf(nfp,"%u ",num);
 rewind(fp);
 r=num%3;
 p=(num-r)/3;
 i=0;
 while(i<p)
 {i=i+1;block=0;
 fread(&block,3,1,fp);printf("\nblock=%u",block);
 x=sign(block);for (j=0;j<20;j++)x2[j]=x[j]+48;
x2[20]='\0';
 fwrite(x2,20,1,nfp);
 }
 if (r!=0)
 {block=0;
  fread(&block,r,1,fp);printf("\nblock=%u",block);
x=sign(block);for (i=0;i<20;i++)x2[i]=x[i]+48;
x2[20]='\0';
 fwrite(x2,20,1,nfp);}
  fclose(fp);
  fclose(nfp);
  }

void perr(s)
char *s;
{
printf("\n%s",s); exit(1);
}

int *mn(int c[40],int a[40])
{int i;
unsigned long d=0;
 int m[40];
 int x[40],y[40];
for(i=0;i<20;i++)
{x[i]=n[i]-48;
y[i]=n[i]-48;
}
x[10]++;
for(i=20;i<40;i++){x[i]=0;y[i]=0;}
	for(i=17;i>=10;i--){d=x[i]+d*10;}
	
	multi(c,a);

		while(cmp(c,x)){
		for(i=10;i<40;i++)m[i-10]=c[i];
		for(i=30;i<40;i++)m[i]=0;
		chu(m,d);
multi(m,y);

sub(c,m);

	}
while(cmp(c,y))
{sub(c,y);}
return(c);
}
	
	
	

int *multi(int n2[40],int n1[40])    /*乘法++*/
{int i;
	
int mul[40];

	int a,b;
	for(i=0;i<40;i++)mul[i]=0;
	for(a=0;a<20;a++)
	{
		for(b=0;b<20;b++)
		{
			mul[a+b]=mul[a+b]+n2[b]*n1[a];
		}
	}
	tz(mul);
	for(a=0;a<40;a++)
	{n2[a]=mul[a];}
return(n2);}

int *tz(int *mut)        /*調整數組++*/   
{
	int a,b,bi,i;

	for(a=0;a<40;a++)
	{
		i=0;
		b=mut[a];
		mut[a]=mut[a]%10;
		while(b)
		{
			i++;
			b=b/10;
			bi=b%10;
			mut[a+i]+=bi;
		}
	}return(mut);
	
}
int cmp(int *n1,int *m)                           /*比較 */
{

	int i=39;

	while(n1[i]==m[i])
	{
		i--;
	}
	if(i<0){return 0;}
else	if(n1[i]>m[i])
	return 1 ;
	else 
return 0 ;
}
		
int *chu(int *m,unsigned long d )  /*除法*/
{unsigned long w1=0;
int i,a;
 int u[40];for(i=0;i<40;i++)
	 u[i]=0;
	for(a=29;a>=0;a--)
{w1=w1*10+m[a];
u[a]=w1/d;
w1=w1%d;
	}
	for(a=29;a>=0;a--)
		m[a]=u[a];
	return(m);
	
}
		 int *sub(int c[40],int q[40])   /*減法++*/
 {
 int i,t;
 for(i=0;i<40;i=i++)
 {if(c[i]>=q[i])
 c[i]=c[i]-q[i];
 else
 {
	 c[i]=c[i]+10-q[i];
	 t=1;
 while(c[i+t]==0){
		 c[i+t]=9; t++;}
 c[i+t]--;}
	 
 }
 
		return(c); }

 
int *sign(unsigned long blo)
{int i;
static int u[40];
	 int a[40];
	 int c[40];
unsigned long d=k;
 for(i=0;i<20;i++)
 { a[i]=blo%10;
 blo=blo/10;}
 for(i=20;i<40;i++)
	{a[i]=0; }
 for(i=1;i<40;i++){c[i]=0;}
 c[0]=1;
 while(d)
 { 
	 while (d%2==0)
	 {
	 d=d/2;
     mn(a,a); }

 d--;
  mn(c,a);
 }
 printf("c=");
 for(i=19;i>=0;i--)
	{ printf("%d",c[i]);}
return (c);
}