密码加密解密

[java]代码库
import java.security.*;
import javax.crypto.*;
 
public class DESPlus {
    private static String strDefaultKey = "wcj";
 
    private Cipher encryptCipher = null;
 
    private Cipher decryptCipher = null;
 
    /**
     * 将byte数组转换为表示16进制值的字符串， 如：byte[]{8,18}转换为：0813， 和public static byte[]
     * hexStr2ByteArr(String strIn) 互为可逆的转换过程
     * 
     * @param arrB
     *            需要转换的byte数组
     * @return 转换后的字符串
     * @throws Exception
     *             本方法不处理任何异常，所有异常全部抛出
     */
    public static String byteArr2HexStr(byte[] arrB) throws Exception {
        int iLen = arrB.length;
        // 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
        StringBuffer sb = new StringBuffer(iLen * 2);
        for (int i = 0; i < iLen; i++) {
            int intTmp = arrB[i];
            // 把负数转换为正数
            while (intTmp < 0) {
                intTmp = intTmp + 256;
            }
            // 小于0F的数需要在前面补0
            if (intTmp < 16) {
                sb.append("0");
            }
            sb.append(Integer.toString(intTmp, 16));
        }
        return sb.toString();
    }
 
    /**
     * 将表示16进制值的字符串转换为byte数组， 和public static String byteArr2HexStr(byte[] arrB)
     * 互为可逆的转换过程
     * 
     * @param strIn
     *            需要转换的字符串
     * @return 转换后的byte数组
     * @throws Exception
     *             本方法不处理任何异常，所有异常全部抛出
     * @author <a href="mailto:leo841001@163.com">LiGuoQing</a>
     */
    public static byte[] hexStr2ByteArr(String strIn) throws Exception {
        byte[] arrB = strIn.getBytes();
        int iLen = arrB.length;
 
        // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
        byte[] arrOut = new byte[iLen / 2];
        for (int i = 0; i < iLen; i = i + 2) {
            String strTmp = new String(arrB, i, 2);
            arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
        }
        return arrOut;
    }
 
    /**
     * 默认构造方法，使用默认密钥
     * 
     * @throws Exception
     */
    public DESPlus() throws Exception {
        this(strDefaultKey);
    }
 
    /**
     * 指定密钥构造方法
     * 
     * @param strKey
     *            指定的密钥
     * @throws Exception
     */
    public DESPlus(String strKey) throws Exception {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        Key key = getKey(strKey.getBytes());
 
        encryptCipher = Cipher.getInstance("DES");
        encryptCipher.init(Cipher.ENCRYPT_MODE, key);
 
        decryptCipher = Cipher.getInstance("DES");
        decryptCipher.init(Cipher.DECRYPT_MODE, key);
    }
 
    /**
     * 加密字节数组
     * 
     * @param arrB
     *            需加密的字节数组
     * @return 加密后的字节数组
     * @throws Exception
     */
    public byte[] encrypt(byte[] arrB) throws Exception {
        return encryptCipher.doFinal(arrB);
    }
 
    /**
     * 加密字符串
     * 
     * @param strIn
     *            需加密的字符串
     * @return 加密后的字符串
     * @throws Exception
     */
    public String encrypt(String strIn) throws Exception {
        return byteArr2HexStr(encrypt(strIn.getBytes()));
    }
 
    /**
     * 解密字节数组
     * 
     * @param arrB
     *            需解密的字节数组
     * @return 解密后的字节数组
     * @throws Exception
     */
    public byte[] decrypt(byte[] arrB) throws Exception {
        return decryptCipher.doFinal(arrB);
    }
 
    /**
     * 解密字符串
     * 
     * @param strIn
     *            需解密的字符串
     * @return 解密后的字符串
     * @throws Exception
     */
    public String decrypt(String strIn) throws Exception {
        return new String(decrypt(hexStr2ByteArr(strIn)));
    }
 
    /**
     * 从指定字符串生成密钥，密钥所需的字节数组长度为8位 不足8位时后面补0，超出8位只取前8位
     * 
     * @param arrBTmp
     *            构成该字符串的字节数组
     * @return 生成的密钥
     * @throws java.lang.Exception
     */
    private Key getKey(byte[] arrBTmp) throws Exception {
        // 创建一个空的8位字节数组（默认值为0）
        byte[] arrB = new byte[8];
 
        // 将原始字节数组转换为8位
        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
            arrB[i] = arrBTmp[i];
        }
 
        // 生成密钥
        Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
 
        return key;
    }
 
    public static void main(String[] args) {
        try {
            String test = "1234";
            // DESPlus des = new DESPlus();//默认密钥
            DESPlus des = new DESPlus("wcj");// 自定义密钥
            System.out.println("加密前的字符：" + test);
            System.out.println("加密后的字符：" + des.encrypt(test).toUpperCase());
            System.out.println("解密后的字符：" + des.decrypt(des.encrypt(test)));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
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