enc_rsa.java

java程序实现的RSA算法

import java.security.interfaces.*;
import java.math.*;
import java.io.*;
//类声明,用到的大数均由JAVA类库提供
public class Enc_RSA{
  public static void main(String args[]) throws Exception{
    String s="Hello World!";
    FileInputStream f=new FileInputStream("Skey_RSA_pub.txt");
    ObjectInputStream b=new ObjectInputStream(f);
    RSAPublicKey pbk=(RSAPublicKey)b.readObject( );//得到RSA公钥描述结构类
    BigInteger e=pbk.getPublicExponent();//得到公钥
    BigInteger n=pbk.getModulus();//得到公共模
    
    //BigInteger n = new BigInteger("65531".getBytes());//打算用自己的公钥
    //BigInteger e = new BigInteger("17".getBytes());
    
    System.out.println("e= "+e);
    System.out.println("n= "+n);
    byte ptext[]=s.getBytes();//将明文转化成UTF8格式
    BigInteger m=new BigInteger(ptext);
    System.out.println("m= "+m);
    BigInteger c=m.modPow(e,n); //加密
    System.out.println("c= "+c);
    String cs=c.toString( );
    BufferedWriter out= 
      new BufferedWriter(new OutputStreamWriter(
        new FileOutputStream("Enc_RSA.txt")));
    out.write(cs,0,cs.length( ));
    out.close( );
    
  }
}