1、密码学DES实验报告南京信息工程大学实验(实习)报告实验(实习)名称 实验(实习)日期 得分 指导教师 -系 计算机 专业 软件工程 年 2011 班次 3 姓名 唐一鑫 学号 24 一实验目的1.理解对称加密算法的原理和特点2.理解DES算法的加密原理二实验内容第一阶段:初始置换IP。在第一轮迭代之前,需要加密的64位明文首先通过初始置换IP的作用,对输入分组实施置换。最后,按照置换顺序,DES将64位的置换结果分为左右两部分,第1位到第32位记为L0,第33位到第64位记为R0。第二阶段:16次迭代变换。DES采用了典型的Feistel结构,是一个乘积结构的迭代密码算法。其算法的核心是算法
2、所规定的16次迭代变换。DES算法的16才迭代变换具有相同的结构,每一次迭代变换都以前一次迭代变换的结果和用户密钥扩展得到的子密钥Ki作为输入;每一次迭代变换只变换了一半数据,它们将输入数据的右半部分经过函数f后将其输出,与输入数据的左半部分进行异或运算,并将得到的结果作为新的有半部分,原来的有半部分变成了新的左半部分。用下面的规则来表示这一过程(假设第i次迭代所得到的结果为LiRi):Li=Ri-1;Ri=Li-1f(Ri-1,Ki);在最后一轮左与右半部分并未变换,而是直接将R16L16并在一起作为未置换的输入。第三阶段:逆(初始)置换。他是初始置换IP的逆置换,记为IP-1。在对16次迭
3、代的结果(R16L16)再使用逆置换IP-1后,得到的结果即可作为DES加密的密文Y输出,即Y=IP-1(R16L16)三流程图&原理图输入字符设置密码加密是否解密输入密码密码正确解密密码错误程序结束是否重新输入密码流程图要加密的字符转换为二进制(64位)初始置换(IP)左32 右32放大变换48位设置密码转换为二进制64位形成密钥(56位)左移合并为子密钥(48位)S盒置换P盒置换左右交换异或循环16次异或最后置换解密为加密的逆过程DES原理图四实验结果五实验总结通过这次的实验 我知道了des的基本原理 虽然DES已经过时了,但是他的原理和思想并没有过时,学号DES有助于学好当下比较流行的A
4、ES源程序:#include#include using namespace std;const static char IP64 =/初始置换 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, 55, 47,
5、 39, 31, 23, 15, 7;const static char EP156 =/密钥置换(原64位去掉奇偶校验位后) 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;const static char LOO
6、P16 =/左移 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1;const static char EP248 =/选择子密钥 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;static const char EC48 =/放大换位
7、 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1;const static char SBox8416 =/8个S盒 / S1 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 , 0, 15, 7, 4, 14, 2, 13, 1, 1
8、0, 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 , / S2 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 , 3, 13, 4, 7, 15, 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
9、, 15 , 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 , / S3 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, 2, 12, 5, 10, 14, 7 , 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 , / S4 7, 13, 1
10、4, 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, 14 , / S5 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 , 14, 11, 2, 12, 4, 7, 13, 1,
11、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 , / S6 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 , 10, 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, 1
12、1, 6 , 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 , / S7 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, 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 , / S8 13, 2, 8
13、, 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, 9, 0, 3, 5, 6, 11 ;const static char PP32 =/P盒置换 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26,5, 18, 31, 10,
14、 2, 8, 24, 14,32, 27, 3, 9, 19, 13, 30, 6,22, 11, 4, 25,;const static char LP64 =/末置换 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, 2
15、6, 33, 1, 41, 9, 49, 17, 57, 25;static bool M64, tmp32, *Li = &M0, *Ri = &M32;static bool SubKey1648;/16个子密钥class CDES/定义DES类 public: /void Mode();/模式 void Encryption(char out8,char In8);/加密函数 void Decryption(char out8,char In8);/解密函数;void ByteToBit(bool *Out, const char *In, int bits)/字符转换成字节 int i
16、; for(i=0;i(i%8)&1; void BitToByte(char *Out,const bool *In,int bits)/字节转换成字符 int i; memset(Out,0,(bits+7)/8); for(i=0;ibits;i+) Outi/8|=Ini(i%8); void RotateL(bool*In,int len,int loop)/循环左移 static bool tmp256; memcpy(tmp,In,loop); memcpy(In,In+loop,len-loop); memcpy(In+len-loop,tmp,loop); void Xor(
17、bool*InA,const bool*InB,int len)/异或 int i; for(i=0;ilen;i+) InAi=InBi; void Transform(bool*Out,bool*In,const char*Table,int len)/各个置换转换 int i; static bool tmp256; for(i=0;ilen;i+) tmpi=InTablei-1; memcpy(Out,tmp,len);void S_func(bool Out32,const bool In48)/将48位转换成32位 int j,m,n; /膨胀后的比特串分为8组,每组6比特。 f
18、or(j=0;j8;j+,In+=6,Out+=4) m = (In0*2)+In5; n = (In1*8)+(In2*4)+(In3*2)+In4; ByteToBit(Out,&SBoxjmn,4); void F_func(bool In32,const bool Ki48) static bool MR48; Transform(MR,In,EC,48); Xor(MR, Ki, 48); /膨胀后的比特串分为8组,每组6比特。各组经过各自的S盒后,又变为4比特,合并后又成为32比特。 S_func(In, MR); /该32比特经过P变换后,输出的比特串才是32比特的f(Ri-1,
19、Ki)。 Transform(In, In, PP, 32);void SetKey(char key8)/生成子密钥 int i; static bool K64, *KL = &K0, *KR = &K28; ByteToBit(K,key,64); /转换为二进制 Transform(K,K,EP1,56); /64比特的密钥K,经过EP1后,生成56比特的串。 /生成16个子密钥 for(i=0;i16;i+) /循环左移,合并 RotateL(KL,28,LOOPi); RotateL(KR,28,LOOPi); Transform(SubKeyi,K,EP2,48); void C
20、DES:Encryption(char out8,char In8)/加密函数 ByteToBit(M,In,64); /转换为二进制 Transform(M,M,IP,64); for(int i=0;i=0;i-) memcpy(tmp,Li,32); F_func(Li,SubKeyi); Xor(Li,Ri,32); memcpy(Ri,tmp,32); Transform(M, M, LP, 64); BitToByte(out, M, 64); / return(out);void main() char key10; char str10; char str110; coutstr; coutkey; SetKey(key); memset(str1,0,sizeof(str1); CDES des; des.Encryption(str1,str); cout加密后为:str1endl; coutn; if(n=1) while(1) coutsec; if(strcmp(sec,key)=0) memset(str,0,sizeof(str); des.Decryption(str,str1); cout解密后为:strendl; break; else cout密码错误!endl; else cout过程结束!endl;
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