1、0x07 0x80 0x80 0x80 0x80 0x80 0x80 0x80。再比如最后一块为7字节,那么填充的数据就为:0x00。在这些准备工作之后,方可对数据进行加密。在解密的时候,还要完成将填充的数据去掉,恢复以前输入的明文。3.DES的工作方式 3.1电子密码本模式(ECB)这种模式是最早采用和最简单的模式,它将加密的数据分成若干组,每组的大小跟加密密钥长度相同,然后每组都用相同的密钥进行加密。一个64位的密钥,如果采用该模式加密,就是将要加密的数据分成每组64位的数据,如果最后一组不够64位,那么就补齐为64位,然后每组数据都采用DES算法的64位密钥进行加密。3.2 加密块链模式
2、(CBC)CBC模式的加密首先也是将明文分成固定长度,(64位)的块,(P0P1.),然后将前面一个加密块输出的密文与下一个要加密的明文块进行XOR(异或)操作计算,将计算结果再用密钥进行加密得到密文。第一明文块加密的时候,因为前面没有加密的密文,所以需要一个初始化向量(IV)。跟ECB方式不一样,通过连接关系,使得密文跟明文不再是一一对应的关系,破解起来更困难,而且克服了只要简单调换密文块可能达到目的的攻击。但是该加密模式的缺点是不能实时解密,也就是说,必须等到每8个字节都接受到之后才能开始加密,否则就不能得到正确的结果。这在要求实时性比较高的时候就显得不合适了。3.3加密反馈模式(CFB)
3、 加密反馈模式(CFB)为了克服必须等待8个字节全部得到才能进行解密的缺点,采用了一个64位,(8个字节)的位移寄存器来获得密文。所以能够实现字符的实时加密和解密,不用再等到8个字节都接受到之后再进行解密。其他特性和CBC差不多。4.DES核心代码4.1加密解密函数 public byte DesEncrypt(byte des_data, int flag) byte format_key = ByteDataFormat(bytekey, flag); byte format_data = ByteDataFormat(des_data, flag); int datalen = form
4、at_data.length; int unitcount = datalen / 8; byte result_data = new bytedatalen; for (int i = 0; i = 1) & (delete_len = 8) ? delete_len : 0; decryptbytearray = new bytetotal_len - delete_len - 8; boolean del_flag = true; for (int k = 0; k delete_len; k+) if (delete_len != result_datatotal_len - 8 -
5、(k + 1) del_flag = false; if (del_flag = true) System.arraycopy(result_data, 0, decryptbytearray, 0, total_len- delete_len - 8); return (flag = 1) ? result_data : decryptbytearray; 5测试结果主界面:加密解密:6总结在做课程设计的过程中,我学会不少东西。大大提高了自己的编程能力和动手能力。与此同时,在这次的课程设计中我也看到了自己所存在的不足之处,通过这次课程设计,我更加系统的掌握了DES加密解密的过程及其原理,DE
6、S加密算法加密效率高,安全性强的相关原理,为以后的学习打下坚实的基础,同时也让我认识到了自己的很多不足,这就在客观上要求自己在以后的学习过程中要更加努力。参考文献1张建 密码学原理及应用技术 清华大学出版社2 张仕 应用密码学 西安电子科技大学出版社3 杨波 现代密码学清华大学出版社完整代码:package 密码学;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;public class DES byte bytekey; public DES(String st
7、rKey) this.bytekey = strKey.getBytes(); / 声明常量字节数组 private static final int IP = 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63,
8、 55, 47, 39, 31, 23, 15, 7 ; / 64 private static final int IP_1 = 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49,
9、 17, 57, 25 ; private static final int PC_1 = 57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4 ; / 56 private static final int PC_2 =
10、14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32 ; / 48 private static final int E = 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17
11、, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1 ; private static final int P = 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25 ; / 32 private static final int S_Box = /S-盒 / S_Box1 1
12、4, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 , 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8 , 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0 , 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 , / S_Box2 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 , 3, 13, 4, 7, 15,
13、2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 , 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 , 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 , / S_Box3 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 , 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 , 13, 6, 4, 9, 8, 15, 3, 0, 11, 1,
14、2, 12, 5, 10, 14, 7 , 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 , / S_Box4 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 , 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 , 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4 , 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2,
15、 14 , / S_Box5 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 , 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 , 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14 , 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 , / S_Box6 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 , 1
16、0, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 , 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6 , 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 , / S_Box7 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 , 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 , 1, 4, 11, 13, 12,
17、 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2 , 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 , / S_Box8 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 , 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 , 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8 , 2, 1, 14, 7, 4, 10, 8, 13, 15, 12
18、, 9, 0, 3, 5, 6, 11 ; private static final int LeftMove = 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2,2, 2, 2, 1 ;/ 左移位置列表 private byte UnitDes(byte des_key, byte des_data, int flag) / 检测输入参数格式是否正确,错误直接返回空值(null) if (des_key.length != 8) | (des_data.length != 8)| (flag ! (flag != 0) throw new RuntimeExceptio
19、n(Data Format Error !); int flags = flag;/ 二进制加密密钥 int keydata = new int64;/ 二进制加密数据 int encryptdata = new int64; / 加密操作完成后的字节数组 byte EncryptCode = new byte8;/ 密钥初试化成二维数组 int KeyArray = new int1648;/ 将密钥字节数组转换成二进制字节数组 keydata = ReadDataToBirnaryIntArray(des_key);/ 将加密数据字节数组转换成二进制字节数组 encryptdata = R
20、eadDataToBirnaryIntArray(des_data);/ 初试化密钥为二维密钥数组 KeyInitialize(keydata, KeyArray); / 执行加密解密操作 EncryptCode = Encrypt(encryptdata, flags, KeyArray); return EncryptCode; / 初试化密钥数组 private void KeyInitialize(int key, int keyarray) int i; int j; int K0 = new int56;/ 特别注意:xxxIPi-1等类似变换 for (i = 0; 56; K0
21、i = keyPC_1i - 1; / 密钥进行PC-1变换 16; LeftBitMove(K0, LeftMovei); / 特别注意: for (j = 0; j -1; i-) MIP_1i = MIP_1i - 1; / 进行IP-1运算 GetEncryptResultOfByteArray(MIP_1, encrypt);/ 返回加密数据 return encrypt; private int ReadDataToBirnaryIntArray(byte intdata) / 将数据转换为二进制数,存储到数组 int IntDa = new int8; 8; IntDai = intdatai; if (IntDai 0) IntDai += 256; IntDai %= 256; int IntVa = new int64; IntVa(i * 8) + 7) - j = IntDai % 2; IntDai = IntDai / 2; return IntVa; private void LeftBitMove(int k, int offset) / 循环移位操作函数 int c0 = new int28; int d0 = new int28; int
copyright@ 2008-2022 冰豆网网站版权所有
经营许可证编号:鄂ICP备2022015515号-1