AES 加密 / 解密 - 工具类

import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
* AES工具类
* 
 * @author think
*
*/
public class AESUtil {
public static final String KEY_ALGORITHM = "AES";

/**
 * 自动生成AES密钥
 * 
 * @param digit
 *            :二进制位数 128,256等
 */
public static String getKey(int digit) {
	try {
		KeyGenerator kg = KeyGenerator.getInstance(KEY_ALGORITHM);
		kg.init(digit);// 要生成多少位，只需要修改这里即可128, 192或256
		SecretKey sk = kg.generateKey();
		byte[] b = sk.getEncoded();
		return byteToHexString(b);
	} catch (NoSuchAlgorithmException e) {
		e.printStackTrace();
		System.out.println("没有此算法。");
	}
	return null;
}

/**
 * 二进制byte[]转十六进制string
 */
public static String byteToHexString(byte[] bytes) {
	StringBuffer sb = new StringBuffer();
	for (int i = 0; i < bytes.length; i++) {
		String strHex = Integer.toHexString(bytes[i]);
		if (strHex.length() > 3) {
			sb.append(strHex.substring(6));
		} else {
			if (strHex.length() < 2) {
				sb.append("0" + strHex);
			} else {
				sb.append(strHex);
			}
		}
	}
	return sb.toString();
}

/**
 * 十六进制string转二进制byte[]
 */
public static byte[] hexStringToByte(String s) {
	byte[] baKeyword = new byte[s.length() / 2];
	for (int i = 0; i < baKeyword.length; i++) {
		try {
			baKeyword[i] = (byte) (0xff & Integer.parseInt(s.substring(i * 2, i * 2 + 2), 16));
		} catch (Exception e) {
			System.out.println("十六进制转byte发生错误！！！");
			e.printStackTrace();
		}
	}
	return baKeyword;
}

/**
 * 使用对称密钥进行加密
 * 
 * @param data
 * @param keys
 * @return
 * @throws Exception
 */
public static String encryption(String data, String keys) throws Exception {
	byte[] keyb = hexStringToByte(keys);
	SecretKeySpec sKeySpec = new SecretKeySpec(keyb, KEY_ALGORITHM);
	Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
	cipher.init(Cipher.ENCRYPT_MODE, sKeySpec);
	byte[] bjiamihou = cipher.doFinal(data.getBytes());
	return byteToHexString(bjiamihou);
}

/**
 * 使用对称密钥进行解密
 * 
 * @param encryptedStr
 * @param keys
 * @return
 * @throws Exception
 */
public static String decrypt(String encryptedStr, String keys) throws Exception {
	byte[] keyb = hexStringToByte(keys);
	byte[] miwen = hexStringToByte(encryptedStr);
	SecretKeySpec sKeySpec = new SecretKeySpec(keyb, KEY_ALGORITHM);
	Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
	cipher.init(Cipher.DECRYPT_MODE, sKeySpec);
	byte[] bjiemihou = cipher.doFinal(miwen);
	return new String(bjiemihou);
}

public static void main(String[] args) throws Exception {
	System.out.println(getKey(256));
}

}