//psw：加密的文本，pswkey：加密的密码，即密钥
String psw="12345",pswkey="999";

//对该DES情况下加密，密钥需要为56位难以人工由string为根据设定，因此这里：
//借助密钥生成器，由new SecureRandom(pswkey.getBytes())，以pswkey为种子值生成密钥
KeyGenerator keyGenerator=KeyGenerator.getInstance("DES");
keyGenerator.init(56,new SecureRandom(pswkey.getBytes()));
Key key=keyGenerator.generateKey();

//加密，DES/ECB/pkcs5padding为：算法/模式/填充 的参数
//参数new BouncyCastleProvider()也可修改为"BC"，要求前面要有Security.addProvider(new BouncyCastleProvider());
Cipher cipher=Cipher.getInstance("DES/ECB/pkcs5padding",new BouncyCastleProvider());
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] out=cipher.doFinal(psw.getBytes());
System.out.println(out);//字节数组，没有编码

//解密
Cipher cipher2=Cipher.getInstance("DES/ECB/pkcs5padding",new BouncyCastleProvider());
cipher2.init(Cipher.DECRYPT_MODE, key);
byte[] in=cipher2.doFinal(out);
System.out.println(new String(in));