rsa(power

加密解密现代密码学的内容c语言编写uoto

#include "stdlib.h"
unsigned long  n;
int e,d;
unsigned p,q;
unsigned char text_8[100];
unsigned text_16[100],secu_16[100];
void public_key_product();
void person_key_product();
int gcd(unsigned long,unsigned long);
unsigned power(unsigned,unsigned,unsigned long);
void convert_16_to_8(unsigned a[100]);
void convert_8_to_16();
void coder();
void decoder();
void get();





main()
{
 while(getch()!='e')
 {
  clrscr();

  printf("Please enter your text to coded:\n");
  get();
  public_key_product();
  person_key_product();
  coder();
  printf("\nThe coded is:\n%s\n",text_8);
  getch();
  printf("\n(d=%d,n=%lu)",d,n);
  decoder();
  printf("\n\nThe code is\n%s\n",text_8);

  printf("p=%ld\n",p);
  printf("q=%ld\n",q);

 }
}



void get()
{
 printf("Enter the text('e' to exit):\n");
 scanf("%s",text_8);
}







int gcd(unsigned long a,unsigned long b)      /*The gcd(),you can get gcd((p-1),(q-1))*/
{
 unsigned long c;
 if(a>=b)
 {
  c=a%b;
  if(c==0)
       return 0;
    else if (c==1)
       return 1;
  else gcd(b,c);
  }
  else gcd(b,a);
}




void public_key_product()         /*The public_key*/
{
 e=3;
 p=2*random(50000)+1+30000;
 while(!is_number(p)&&p<65536);
 {
  p+=2;
 }
 q=2*random(10000)+1+30000;
 while(!is_number(q)&&q<65536);
 {
  q+=2;
 }
 n=(unsigned long )p*(unsigned long)q;
 while(!gcd((unsigned long )(p-1)*(unsigned long )(q-1),e))
 e++;
 printf("(e=%d,n=%lu)",e,n);
}




void person_key_product()         /*The person_key*/
{
 int i=1;
 while((((p-1)*(q-1)*i+1)%e)&&i>0)
 i++;
 d=((p-1)*(q-1)*i+1)/e;
}







int is_number(unsigned n)                /*The is_numer,you can get n*/
{
 unsigned m=1,b=0,a,j=n-1,i,z;
  while(!j%2)
   {
    m*=2;
    b++;
    j/=2;
   }
   m=(n-1)/m;
   a=random(n-1);
   for(j=0;j<1000;j++)
   {
    a+=2;
    if(a>2)
    {
     i=0;
     z=power(a,m,n);
     if((z!=1)&&(z!=(p-1)))
      return 0;

      while((i<b)&&(z!=(p-1)))
      {
       if((i>0)&&(z==1))
          return 0;
         z=power(z,2,p);
         i+=1;
         }
      if(z!=(p-1))return 0;
     }
    return 1;
   }

}



unsigned power(unsigned a,unsigned b,unsigned long c)
{
 unsigned long t=1,mask=1;
 unsigned k=b,j=b;
 int i;

 for(i=0;j>0;j>>=1,i++);

 for(k=(k<<1)|k>>(i-1);b>0;b>>=1,k=(k<<1)|k>>(i-1))
 {
     t=(t*t)%c;
     if(k&mask==1) t=(a*t)%c;
 }
  return t;
}



void convert_8_to_16()
{
  int i;
 for(i=0;i<100;i++)
  text_16[i]=text_8[2*i]*256+text_8[2*i+1];
}

void convert_16_to_8(unsigned a[100])
{
  int i=0,flag=0;
  unsigned temp;
  while(i<200&&flag<100)
  {
   temp=a[flag]/256;
   text_8[i]=temp;
   text_8[i+1]=a[flag]%256;
   i+=2;
   flag++;
  }
}









void coder()
{
 int i;
 i=0;
 convert_8_to_16();
 while(text_16[i]!=0)
 {
 secu_16[i]=power(text_16[i],e,n);
 i++;
 }
 convert_16_to_8(secu_16);
}

void decoder()
{
int i;
 i=0;
 while(secu_16[i]!=0)
 {
 text_16[i]=power(secu_16[i],d,n);
 i++;
 }
 convert_16_to_8(text_16);
}