rsaencryptdecrypt.java

用java的applet编写的一个关于RSA加密解密算法的,不错.同们可以参考参考

源程序：//文件名：RSAEncryptDecrypt.java

/*
A basic extension of the java.applet.Applet class
*/
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.math.*;
import java.util.*;

public class RSAEncryptDecrypt extends Applet implements ActionListener{

final int BLOCKSIZE = 12;
boolean isEncrypted = false;
boolean isSeted = false;

BigInteger P, Q, N, E, D, T;
BigInteger ZERO = new BigInteger("0");
BigInteger ONE = new BigInteger("1");
BigInteger ciphertext[] = new BigInteger[100];
Random rand = new Random();

public void init() {
	super.init();

    Font f = new Font("Helvetica", Font.BOLD, 14);
	setLayout(null);
	addNotify();
	resize(448,512);
	setBackground(new Color(98765432));
	ta_info = new TextArea();
	ta_info.setEditable(false);
	ta_info.setText("Welcome to RSA Demo Applet.\nBefore generating the pair of public key and private key,\nyou must choice the ODD e number, and then press SET button.\n\n");
	ta_info.setLocation(12,336);
	ta_info.setSize(420,160);
	add(ta_info);
	ta_msg = new TextArea();
	ta_msg.setLocation(12,168);
	ta_msg.setSize(420,132);
	ta_msg.setFont(f);
	add(ta_msg);
	tf_e = new TextField();
	tf_e.setLocation(24,36);
	tf_e.setSize(300,24);
	add(tf_e);
	but_set = new Button("Set");
	but_set.setLocation(348,36);
	but_set.setSize(84,24);
	but_set.addActionListener(this);
	add(but_set);
	but_reset = new Button("Reset");
	but_reset.setLocation(348,72);
	but_reset.setSize(84,60);
	but_reset.addActionListener(this);
	add(but_reset);
	but_e = new Button("Apply public key(公钥) e to your message ...");
	but_e.setLocation(24,72);
	but_e.setSize(300,24);
	but_e.addActionListener(this);
	add(but_e);
	but_d = new Button("Apply private key(私钥) d to your message ...");
	but_d.setLocation(24,108);
	but_d.setSize(300,24);
	but_d.addActionListener(this);
	add(but_d);
	label1 = new Label("Input the value of public key e:");
	label1.setLocation(14,12);
	label1.setSize(264,24);
	add(label1);
	label2 = new Label("Message:");
	label2.setLocation(12,144);
	label2.setSize(120,24);
	add(label2);
	label3 = new Label("Operation Information:");
	label3.setLocation(12,312);
	label3.setSize(164,24);
	add(label3);
	//{{INIT_CONTROLS
	//}}
}

public void actionPerformed(ActionEvent event) {
    
    Object src = event.getSource();
    if (src == but_set) {
        if (tf_e.getText().length() == 0) ta_info.append("WARNING: You must input the ODD e number first.\n");
        else {
            if (generatePQNTED(tf_e.getText())) {
                ta_info.append("Congratulation! ...\nYou have generated the pair of public / private key.\n");
                ta_info.append("p: "+P.toString()+"\n");
                ta_info.append("q: "+Q.toString()+"\n");
                ta_info.append("n: "+N.toString()+"\n");
                ta_info.append("e: "+E.toString()+"\n");
                ta_info.append("d: "+D.toString()+"\n");
                ta_info.append("\nAnd now, you can type the message you want in the Message box.\n");
                isSeted = true;
            }
            else ta_info.append("WARNING: The number e must be an odd number(奇数).\n");
        }
    }
    else if (src == but_e) {
        if (ta_msg.getText().length() == 0) ta_info.append("WARNING: You must type some text in the message box.\n");    
        else if (!isSeted) ta_info.append("WARNING: You must SET your key first.\n");
        else {  
            if (isEncrypted) {
                isEncrypted = false;
                ta_msg.setText(Decrypt(E));
                ta_msg.setEnabled(true);
                but_d.setEnabled(true);
            }
            else {
                isEncrypted = true;    
                ta_msg.setText(Encrypt(ta_msg.getText(), E));
                ta_msg.setEnabled(false);
                but_e.setEnabled(false);
            }
        }
    }
    else if (src == but_d) {
        if (ta_msg.getText().length() == 0) ta_info.append("WARNING: You must type some text in the message box.\n");    
        else if (!isSeted) ta_info.append("WARNING: You must SET your key first.\n");
        else {  
            if (isEncrypted) {
                isEncrypted = false;
                ta_msg.setText(Decrypt(D));
                ta_msg.setEnabled(true);
                but_e.setEnabled(true);
            }
            else {
                isEncrypted = true;    
                ta_msg.setText(Encrypt(ta_msg.getText(), D));
                ta_msg.setEnabled(false);
                but_d.setEnabled(false);
            }
        }
    }
    else if (src == but_reset) {
        Reset();    
    }
}

public void Reset() {
	ta_info.setText("Welcome to RSA EncryptDecrypt Applet.\nBefore generating the pair of public key and private key,\nyou must choice the ODD e number, and then press SET button.");
    ta_msg.setText("");
    ta_msg.setEnabled(true);
    tf_e.setText("");
    but_e.setEnabled(true);
    but_d.setEnabled(true);
    isSeted = isEncrypted = false;
}

public BigInteger ChineseRemainder(BigInteger res[]) {
    BigInteger multiplier;
    BigInteger uv[] = Euclid(P, Q);
    BigInteger e[] = new BigInteger[2];
    e[0] = uv[1].multiply(Q);
    e[1] = uv[0].multiply(P);
    return ((e[0].multiply(res[0])).add(e[1].multiply(res[1]))).mod(N);
}

public String Encrypt(String msg, BigInteger key) {
    byte swap[] = msg.getBytes();
    byte segment[];
    String str = null;
    int copies = swap.length / BLOCKSIZE;
    if (swap.length % BLOCKSIZE > 0) copies++;
    for (int i = 0; i < copies; i++) {
        segment = copyBytes(i, swap);
        ciphertext[i] = new BigInteger(segment);
        ciphertext[i] = ciphertext[i].modPow(key, N);
        segment = ciphertext[i].toByteArray();
        if (str == null) str = new String(segment);
        else str += new String(segment);
    }
    return str;
}

private byte[] copyBytes(int x, byte tmp[]) {
    byte swap[] = new byte[12];
    int count = 0;
    for (int i = x * BLOCKSIZE; i < (x+1) * BLOCKSIZE; i++) {
        if (i >= tmp.length) break;
        swap[count++] = tmp[i];
    }
    return swap;
}

public String Decrypt(BigInteger key) {
    int i = 0;
    byte swap[];
    String str = null;
    do {
        ciphertext[i] = ciphertext[i].modPow(key, N);
        swap = ciphertext[i].toByteArray();
        if (str == null) str = new String(swap);
        else str += new String(swap);
    } while (ciphertext[++i] != null);
    return str;
}

    public boolean generatePQNTED(String e) {
    E = new BigInteger(e);
    if (E.mod(new BigInteger("2")).equals(ZERO)) return false;
    do {
        P = new BigInteger(512, 10, rand);
        Q = new BigInteger(512, 10, rand);
        T = (P.subtract(ONE)).multiply(Q.subtract(ONE));
    } while (!(E.gcd(T)).equals(ONE));
    N = P.multiply(Q);
    BigInteger tmp[] = Euclid(E, T);
    D = tmp[0];
    return true;
}

public BigInteger[] Euclid(BigInteger x, BigInteger y) {
    int n = 2;
    BigInteger r[] = new BigInteger[3];
    BigInteger q[] = new BigInteger[3];
    BigInteger u[] = new BigInteger[3];
    BigInteger v[] = new BigInteger[3];

    r[0] = x;
    r[1] = y;
    u[0] = new BigInteger("1");
    v[0] = new BigInteger("0");
    u[1] = new BigInteger("0");
    v[1] = new BigInteger("1");
    while (!r[(n-1)%3].equals(ZERO)) {
        q[n%3] = r[(n-2)%3].divide(r[(n-1)%3]);
        r[n%3] = r[(n-2)%3].remainder(r[(n-1)%3]);
        // Un = Un-2 - QnUn-1
        u[n%3] = u[(n-2)%3].subtract(q[n%3].multiply(u[(n-1)%3]));
        // Vn = Vn-2 - QnVn-1
        v[n%3] = v[(n-2)%3].subtract(q[n%3].multiply(v[(n-1)%3]));

        n++;
    }
    BigInteger result[] = new BigInteger[2];
    result[0] = u[(n-2)%3];
    result[1] = v[(n-2)%3];
    return result;
}

TextArea ta_info;
TextArea ta_msg;
TextField tf_e;
Button but_set;
Button but_reset;
Button but_e;
Button but_d;
Label label1;
Label label2;
Label label3;
}