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为了使C端与java端的3des加解密互通，我们一般使用“DESede/ECB/NoPadding”加密模式；

而在我们java端，我们都知道3des的密钥都是24字节的，而C端是16字节，此处为重点：我们java端的密钥组成为16字节密钥 + 其前8个字节组成24字节密钥；

请看代码：

private static byte\[\] fillTo24(byte\[\] key) { if (null != key && key.length == 16) { return Util.pinJie2(key, Util.subBytes(key, 0, 8)); } return null; }
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1. 全部代码为：

public class DES3Utils { // 向量 public final static String iv = "12345678"; // 3des加密 public static final String algorithm = "DESede"; // 加密 src为源数据的字节数组 public static byte\[\] encryptBy3DES(byte\[\] src, byte\[\] key) { return init(src, key, true, 0); } // 解密函数 public static byte\[\] decryptBy3DES(byte\[\] src, byte\[\] key) { return init(src, key, false, 0); } /\*\* \* @param src 需要加密的文字 \* @return 加密后的文字 \* @throws Exception 加密失败 \*/ public static byte\[\] encryptBy3DESCBC(byte\[\] src, byte\[\] key) { byte\[\] fillTo24 = fillTo24(key); if (null == fillTo24) return null; try { SecretKey deskey = new SecretKeySpec(fillTo24, algorithm); Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding"); IvParameterSpec ips = new IvParameterSpec(iv.getBytes()); cipher.init(Cipher.ENCRYPT\_MODE, deskey, ips); return cipher.doFinal(src); } catch (Exception e) { e.printStackTrace(); } return null; } /\*\* \* 3DES解密 \* \* @param encryptText 加密文本 \* @return \* @throws Exception \*/ public static byte\[\] decryptBy3DESCBC(byte\[\] encryptText, byte\[\] key) { byte\[\] fillTo24 = fillTo24(key); if (null == fillTo24) return null; try { SecretKey deskey = new SecretKeySpec(fillTo24, algorithm); Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding"); IvParameterSpec ips = new IvParameterSpec(iv.getBytes()); cipher.init(Cipher.DECRYPT\_MODE, deskey, ips); return cipher.doFinal(encryptText); } catch (Exception e) { e.printStackTrace(); } return null; } /\*\* \* @param src 需要加密的文字 \* @return 加密后的文字 \* @throws Exception 加密失败 \*/ public static byte\[\] encryptBy3DESECB(byte\[\] src, byte\[\] key) { return init(src, key, true, 1); } /\*\* \* 3DES解密 \* \* @param encryptText 加密文本 \* @return \* @throws Exception \*/ public static byte\[\] decryptBy3DESECB(byte\[\] encryptText, byte\[\] key) { return init(encryptText, key, false, 1); } private static byte\[\] init(byte\[\] data, byte\[\] key, boolean mode, int type) { byte\[\] fillTo24 = fillTo24(key); if (null == fillTo24) return null; String types = null; try { SecretKey deskey = new SecretKeySpec(fillTo24, algorithm); switch (type) { case 0: types = "DESede"; break; case 1: types = "DESede/ECB/NoPadding"; break; case 2: types = "DESede/ECB/PKCS5Padding"; break; } Cipher cipher = Cipher.getInstance(types); if (mode) cipher.init(Cipher.ENCRYPT\_MODE, deskey); else cipher.init(Cipher.DECRYPT\_MODE, deskey); return cipher.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return null; } private static byte\[\] fillTo24(byte\[\] key) { if (null != key && key.length == 16) { return Util.pinJie2(key, Util.subBytes(key, 0, 8)); } return null; } }
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