rsa.java

用java语言编写的rsa加密解密算法

import java.io.*;
import java.math.*;
import java.security.*;

import javax.swing.*;

public class RSA
    implements Serializable
{
  private final static BigInteger one = BigInteger.ONE;
  private final static SecureRandom random = new SecureRandom();

  private BigInteger privateKey = null;
  private BigInteger publicKey = null;
  private BigInteger modulus = null;

  private BigInteger p1 = null;
  private BigInteger p2 = null;

  //Ces variables doivent 阾re initialis?pour l'encrytage de donn閑s.
  private BigInteger modulusE;
  private BigInteger publicKeyE;

  private int N;
  private BigInteger phi0;
  public RSA(int N)  //输入想要的密钥的比特N，自动生成大素数和密钥
  {
    this.N = N;
    // generate an N-bit (roughly) public and private key
   
    p1 = BigInteger.probablePrime(N / 2, random);    //p1和p2即是两个大素数
  
    p2 = BigInteger.probablePrime(N / 2, random);

    phi0 = (p1.subtract(one)).multiply(p2.subtract(one));  
   
    modulus = p1.multiply(p2);

    setPublicKey();

    privateKey = publicKey.modInverse(phi0);  //私钥

    modulusE = modulus;
    publicKeyE = publicKey;
  }

/* public RSA(BigInteger inputp1,BigInteger inputp2)  
  {
    N=10;
    p1=inputp1;
    p2=inputp2;
    phi0 = (p1.subtract(one)).multiply(p2.subtract(one));  
    modulus = p1.multiply(p2);
    setPublicKey();
    privateKey=publicKey.modInverse(phi0);  
    modulusE = modulus;
    publicKeyE = publicKey;
}
*/

  public RSA(BigInteger inputp1,BigInteger inputp2,BigInteger inputpublicKey)  
  {
    N=100;
    p1=inputp1;
    p2=inputp2;
    phi0 = (p1.subtract(one)).multiply(p2.subtract(one));  
    modulus = p1.multiply(p2);
    publicKey=inputpublicKey;
    privateKey=publicKey.modInverse(phi0);  
    modulusE = modulus;
    publicKeyE = publicKey;
}


  public BigInteger getModulus()
  {
    return modulus;
  }

//renvois la variable public publicKey utilis?par d'autre pour l'encryption

  public BigInteger getPublicKey()
  {
    return publicKey;
  }

//Cette variable doit 阾re initialis?pour 阾re en mesure d'encrypt?
//Ces

  public void setPublicKey(BigInteger p, BigInteger n)
  {
    publicKeyE = p;
    modulusE = n;
  }

  /**
   * @param xor BigInteger
   *
   * Cette m閠hode est employer pour encrypt?et pour d閏rypt?les cl閑s
   * C'est l'avantage du ou exclusif il sufi de r閜閠?la m阭e opr閞ation pour
   * encod?et d閏od?
   **/

  public void xOrClePrive(BigInteger xor)
  {
    xor = xor.pow(4);
    privateKey = privateKey.xor(xor);

  }

  /**
   * s'assure que privateKey
   * 1. n'a aucun autre diviseur que 1
   * 2. qu'il est plus grand que le plus grand entre p1 et p2
   * 3. qu'il est plus petit que p1*p2
   * */
  private void setPrivateKey()
  {
    do
    {
      privateKey = BigInteger.probablePrime(N / 2, random);
    }
    while (privateKey.gcd(phi0).intValue() != 1 ||
           privateKey.compareTo(modulus) != -1 ||
           privateKey.compareTo(p1.max(p2)) == -1);
  }

  private void setPublicKey()
  {
    do
    {
      publicKey = BigInteger.probablePrime(N / 2, random);
    }
    while (publicKey.gcd(phi0).intValue() != 1 ||
           publicKey.compareTo(phi0) != -1 ||
           publicKey.compareTo(one) !=1);
  }

 

  /*
   Encrypte le message avec les cl閟 public
   pour l'encryption les cl閟 public doivent etre initialis閑s
   le message doit 阾re divis?en paket de N / 8 octects ou bytes
   */
  public BigInteger encrypt(BigInteger message)
  {
    BigInteger rep = null;
    String str_message = new String(message.toByteArray());
    if (message != null)
    {
      if (str_message.length() <= (N / 8))
        if (publicKeyE != null && modulusE != null &&
            message.toByteArray().length < Integer.MAX_VALUE)
          rep = message.modPow(publicKeyE, modulusE);
    }
    return rep;
  }

  public BigInteger decrypt(BigInteger encrypted)
  {
    return encrypted.modPow(privateKey, modulus);
  }

  public String toString()
  {
    String s = "";
    s+="p ="+ p1+"\n";
    s+="q ="+ p2+"\n";
    s += "publickey  = " + publicKey + "\n";
    s += "Privatekey = " + privateKey+"\n";
    s += "modulus = " + modulus+ "\n";
    return s;
  }
  
  public static void main( String[] args )
  { 
    BigInteger inming=new BigInteger("19");
    BigInteger miwen=null;
    BigInteger mingwen=null;
    BigInteger inp1=new BigInteger("7");
    BigInteger inp2=new BigInteger("17");
    BigInteger inpubkey=new BigInteger("5");
    RSA rr=new RSA(10);
    //RSA rr=new RSA(inp1,inp2);
    //RSA rr=new RSA(inp1,inp2,inpubkey);
   
    System.out.println(rr);
    miwen=rr.encrypt(inming);
    System.out.println("密文："+miwen);
    mingwen=rr.decrypt(miwen);
    System.out.println("明文:"+mingwen+"\n");
    }
}