运用DES进行密码的加密以及解密
/**
* DES加密工具
* @author zhang
*
*/
public class DesUtil {
// KeyGenerator 提供对称密钥生成器的功能，支持各种算法
private KeyGenerator keygen;
// SecretKey 负责保存对称密钥
private SecretKey deskey;
// Cipher负责完成加密或解密工作
private Cipher c;
// 该字节数组负责保存加密的结果
private byte[] cipherByte;
@SuppressWarnings("restriction")
public DesUtil() throws NoSuchAlgorithmException, NoSuchPaddingException{
Security.addProvider(new com.sun.crypto.provider.SunJCE());
// 实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常)
keygen = KeyGenerator.getInstance("DES");
// 生成密钥
deskey = keygen.generateKey();
// 生成Cipher对象,指定其支持的DES算法
c = Cipher.getInstance("DES");
}
/**
* 对字符串加密
*
* @param str
* @return
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
public String Encrytor(String str) throws InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
// 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式
c.init(Cipher.ENCRYPT_MODE, deskey);
byte[] src = str.getBytes();
// 加密，结果保存进cipherByte
cipherByte = c.doFinal(src);
return encode(cipherByte);
}
/**
* 对字符串解密
*
* @param buff
* @return
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
public String Decryptor(String text) throws InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
// 根据密钥，对Cipher对象进行初始化，DECRYPT_MODE表示加密模式
c.init(Cipher.DECRYPT_MODE, deskey);
byte[] buff = decode(text);
cipherByte = c.doFinal(buff);
return new String(cipherByte);
}
private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
'2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };
private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
-1, -1, -1 };
/**
* 编码转换成字符串
* @param data
* @return
*/
public static String encode(byte[] data) {
StringBuffer sb = new StringBuffer();
int len = data.length;
int i = 0;
int b1, b2, b3;
while (i < len) {
b1 = data[i++] & 0xff;
if (i == len) {
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
sb.append("==");
break;
}
b2 = data[i++] & 0xff;
if (i == len) {
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
sb.append("=");
break;
}
b3 = data[i++] & 0xff;
sb.append(base64EncodeChars[b1 >>> 2]);
sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
sb.append(base64EncodeChars[b3 & 0x3f]);
}
return sb.toString();
}
/**
* 字符串转换为字节
* @param str
* @return
*/
public static byte[] decode(String str) {
byte[] data = str.getBytes();
int len = data.length;
ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
int i = 0;
int b1, b2, b3, b4;
while (i < len) {
do {
b1 = base64DecodeChars[data[i++]];
} while (i < len && b1 == -1);
if (b1 == -1) {
break;
}
do {
b2 = base64DecodeChars[data[i++]];
} while (i < len && b2 == -1);
if (b2 == -1) {
break;
}
buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
do {
b3 = data[i++];
if (b3 == 61) {
return buf.toByteArray();
}
b3 = base64DecodeChars[b3];
} while (i < len && b3 == -1);
if (b3 == -1) {
break;
}
buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
do {
b4 = data[i++];
if (b4 == 61) {
return buf.toByteArray();
}
b4 = base64DecodeChars[b4];
} while (i < len && b4 == -1);
if (b4 == -1) {
break;
}
buf.write((int) (((b3 & 0x03) << 6) | b4));
}
return buf.toByteArray();
}这里，运用DES加密，解密返回的本来都是byte[],因为用new String（byte[], "UTF-8"）转为字符串之后，再通过String.getBytes()返回的byte[]是不一致的。故需要运用以上的转换方法再次转码。
