Digital Envelope v1.0
Submitted By:
ParvezMI
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import java.io.*;
class Rsa
{
public long n,e,d;
Rsa()
{
RSAKeyGen();
}
//-----------------------------------------------------
public static boolean isPrime(long n)
{
boolean b=true;
long i;
for(i=2;i<n;i++)
if(n%i==0) { b=false; break; }
return b;
}
//-----------------------------------------------------
public static long Power(long x,long y)
{
long ans=1,i;
if(x==1) return x;
for(i=1;i<=y;i++)
ans*=x;
return(ans);
}
//-----------------------------------------------------
public static String ToBin(long x)
{
String ans="",ans1="";
int i=0;
while(x>=1)
{
if(x%2==1) ans=ans+"1"; else ans=ans+"0";
x/=2; i++;
}
if(x==1) { ans=ans+"1"; i++; }
for(i=ans.length()-1;i>=0;i--)
ans1=ans1+ans.charAt(i);
return(ans1);
}
//-----------------------------------------------------
public static long Crypt(long x,long key,long n) // (x^y)%z //Method 2
{
String B="";
int i;
B=ToBin(key);
long ans=1;
int c=1;
for(i=0;i<B.length();i++)
{
c=2*c;
ans=(ans*ans)%n;
if(B.charAt(i)=='1')
{
c=c+1;
ans=(ans*x)%n;
}
}
return(ans);
}
//-----------------------------------------------------
void RSAKeyGen()
{
/* K E Y G E N E R A T I O N */
long p=1,q=2,n1,x;
// Reading 2 random prime-numbers from 20 to 50
while(true)
{
p=(long)(Math.floor((Math.random())*150))+2;
q=(long)(Math.floor((Math.random())*150))+2;
if(p>2 && q>2 && p!=q && isPrime(p) && isPrime(q))
{
n = p * q;
n1 = (p-1) * (q-1);
x=n1+1;
for(e=2;e<=x/2;e++)
{
if(x%e==0) break;
}
d=x/e;
if(e!=1 && d!=1 && e!=d && q!=e && q!=d && p!=e && p!=d) break;
}
}
System.out.println("p = "+p);
System.out.println("q = "+q);
System.out.println("n =(p*q) = "+n);
System.out.println("n1=(p-1)*(q-1)= "+n1);
System.out.println("e = "+e);
System.out.println("d = "+d);
System.out.println("Public Key : { "+e+","+n+" }");
System.out.println("Private Key : { "+d+","+n+" }");
} //keygen function ends here
}//RSA class ends here
public class Rsa1
{
public static void main(String []args)
{
long P1=127,P2,Cypher,i;
Rsa rs=new Rsa();
Cypher=rs.Crypt(P1,rs.e,rs.n); //Encrypting using public-key 'e'
P2=rs.Crypt(Cypher,rs.d,rs.n);//Decrypting using private key 'd'
System.out.println("PlainText Before Encryption is : "+P1);
System.out.println("Cypher is : "+Cypher);
System.out.println("PlainText After Decryption is : "+P2);
System.out.println("----------------------------------------");
}// main ends here
}//"Rsa1.java" Class Ends here
