关于java：AES加密 – 如何解密加密的字符串？

AES encryption - how to later decrypt the encrypted string?

我有一个Java程序。这是一个AES加密-解密程序。该程序有一个图形用户界面，可以输入字符串并显示AES加密字符串。程序还使用代码中编写的解密函数显示原始字符串。界面是这样的，当输入字符串并单击convert按钮时，加密和解密的结果将显示在面板中。这是节目单。

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import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.io.*;

public class AESGUI extends JPanel {

public static void main(String[] args) {
JFrame frame = new JFrame("AES Encryption");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(600,300));

frame.setLocationRelativeTo(null);
frame.setResizable(false);

AESGUI p = new AESGUI();

frame.getContentPane().add(p);
frame.pack();
frame.setVisible(true);
}

private JTextField in;
private JTextArea out;

public AESGUI() {
JLabel info = new JLabel("Type any String");
in = new JTextField(20);
JButton encrypt = new JButton("Encrypt");
out = new JTextArea(10,40);

out.setEditable(false);

encrypt.addActionListener(new encryptListener());
in.addActionListener(new encryptListener());

add(info);
add(in);
add(encrypt);
add(out);
add(new JScrollPane(out));
}

private class encryptListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
String data = in.getText();
if (data.length() == 0) { }
else
try {
String en = encrypt(data);
out.append("Encrypted string:" + en +"
");
out.append("Original String:" + decrypt(en) +"

");
} catch(Exception ex) { }
}
}

public String asHex(byte[] buf) {
StringBuffer strbuf = new StringBuffer(buf.length * 2);
int i;
for (i = 0; i < buf.length; i++) {
if (((int) buf[i] & 0xff) < 0x10)
strbuf.append("0");
strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
}
return strbuf.toString();
}

private SecretKeySpec skeySpec;
private Cipher cipher;
private byte[] encrypted;

public String encrypt(String str) throws Exception {
// Get the KeyGenerator
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128); // 192 and 256 bits may not be available

// Generate the secret key specs.
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
skeySpec = new SecretKeySpec(raw,"AES");

// Instantiate the cipher
cipher = Cipher.getInstance("AES");

cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

encrypted = cipher.doFinal(str.getBytes());
return asHex(encrypted);
}

public String decrypt(String str) throws Exception {
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] original = cipher.doFinal(encrypted);
String originalString = new String(original);
return originalString;
}

}

这个程序不会告诉用户使用哪个密钥来加密字符串。因为它不告诉用户密钥，所以用户以后无法解密加密的字符串。程序以十六进制编码显示加密字符串。为了以后解密字符串，最好更改程序以便程序基于密码创建密钥，还是更改程序以便向用户显示随机生成的密钥，以便用户以后解密字符串？