Java 实现Rsa 加密

import java.io.*;

public class Rsa
{
private int p=0;
private int q=0;
private long n=0;
private long m=0;

private long public_key=0;//公匙
private long private_key=0;//密匙

private long text=0;//明文
private long secretword=0;//密文
private long word=0;//解密后明文

//判断是否为素数
public boolean primenumber(long t)
{
long k=0;
k=(long)Math.sqrt((double)t);
boolean flag=true;
outer:for(int i=2;i<=k;i++)
{
if((t%i)==0)
{
flag = false;
break outer;
}
}
return flag;
}
//输入PQ
public void inputPQ()throws Exception
{
do{
System.out.println("请输入素数p: ");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String br=stdin.readLine();
this.p=Integer.parseInt(br);
}
while(!
primenumber(this.p));
do{
System.out.println("请输入素数q: ");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String br=stdin.readLine();
this.q=Integer.parseInt(br);
}
while(!primenumber(this.q));
this.n=this.p*this.q;
this.m=(p-1)*(q-1);
System.out.println("这两个素数的乘积为p*q："+this.n);
System.out.println("所得的小于Ｎ并且与Ｎ互素的整数的个数为m=(p-1)(q-1)："+this.m);
}
//求最大公约数
public long gcd(long a,long b)
{
long gcd;
if(b==0)
gcd=a;
else
gcd=gcd(b,a%b);
System.out.println("gcd:"+gcd);
return gcd;

}
//输入公匙
public void getPublic_key()throws Exception
{
do{
System.out.println("请输入一个公钥的值，这个值要求小于m并且和m互质： ");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String br=stdin.readLine();
this.public_key=Long.parseLong(br);
}while((this.public_key >= this.m) (this.gcd(this.m,this.public_key)!
=1));
System.out.println("公钥为："+this.public_key);
}
//计算得到密匙
public void getPrivate_key()
{
long value=1;
outer:for(long i=1;;i++)
{
value=i*this.m+1;
System.out.println("value: "+value);
if((value%this.public_key==0)&& (value/this.public_key < this.m))
{
this.private_key=value/this.public_key;
break outer;
}
}
System.out.println("产生的一个私钥为："+this.private_key);
}
//输入明文
public void getText()throws Exception
{
System.out.println("请输入明文：");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String br=stdin.readLine();
this.text=Long.parseLong(br);
}
//加密、解密计算
public long colum(long y,long n,long key)
{
long mul;
if(key==1)
mul=y%n;
else
mul=y*this.colum(y,n,key-1)%n;
return mul;
}

//加密后解密
public void pascolum()throws Exception
{
this.getText();
System.out.println("输入明文为: "+this.text);
//加密
this.secretword=this.colum(this.text,this.n,this.public_key);
System.out.println("所得的密文为："+this.secretword);
//解密
this.word=this.colum(this.secretword,this.n,this.private_key);
System.out.println("解密后所得的明文为："+this.word);

}
public static void main(String []args)throws Exception
{
Rsa t = new Rsa();
t.inputPQ();
t.getPublic_key();
t.getPrivate_key();
t.pascolum();
}

}