3DES是继DESeasy被破解后的DES加密升级版，它属于对称加密。

可指定24位长度的密钥。在java API中也有事实上现，代码例如以下：

/** * 3DES 的Java SDK API 实现 * @author dxd * 201406917 */public class DES3 {	private static final String Algorithm = "DESede";//　定义　加密算法,可用	//keybyte为加密密钥。长度为24字节    //src为被加密的数据缓冲区（源）    public static byte[] encryptMode(byte[] keybyte, byte[] src) {       try {            //生成密钥            SecretKey deskey = new SecretKeySpec(keybyte, Algorithm);            //加密            Cipher c1 = Cipher.getInstance(Algorithm);            c1.init(Cipher.ENCRYPT_MODE, deskey);            return c1.doFinal(src);        } catch (java.security.NoSuchAlgorithmException e1) {            e1.printStackTrace();        } catch (javax.crypto.NoSuchPaddingException e2) {            e2.printStackTrace();        } catch (java.lang.Exception e3) {            e3.printStackTrace();        }        return null;    }    //keybyte为加密密钥，长度为24字节    //src为加密后的缓冲区    public static byte[] decryptMode(byte[] keybyte, byte[] src) {          try {            //生成密钥            SecretKey deskey = new SecretKeySpec(keybyte, Algorithm);            //解密            Cipher c1 = Cipher.getInstance(Algorithm);            c1.init(Cipher.DECRYPT_MODE, deskey);            return c1.doFinal(src);        } catch (java.security.NoSuchAlgorithmException e1) {            e1.printStackTrace();        } catch (javax.crypto.NoSuchPaddingException e2) {            e2.printStackTrace();        } catch (java.lang.Exception e3) {            e3.printStackTrace();        }        return null;    }    //转换成十六进制字符串    public static String byte2hex(byte[] b) {        String hs="";        String stmp="";        for (int n=0;n

调用时能够：

byte[] keydata = {     		(byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03, (byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07,     		(byte) 0x08, (byte) 0x09, (byte) 0x0a, (byte) 0x0b, (byte) 0x0c, (byte) 0x0d, (byte) 0x0e, (byte) 0x0f,     		(byte) 0x10, (byte) 0x11, (byte) 0x12, (byte) 0x13, (byte) 0x14, (byte) 0x15, (byte) 0x16, (byte) 0x17, };	String src = "3DES加密算法" ;	byte[] encoded = DES3.encryptMode(keydata, src.getBytes());	System.out.println("DES3-->Encoded = " + new String(encoded));

则能够计算出原文src加密后的密文。