des算法简介_des算法个人资料_des算法微博_百科网
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des算法简介_des算法个人资料_des算法微博

2017-09-21 21:05:25 科学百科 阅读 4 次

基本原理/des算法 编辑

des算法
des算法结构

其入口参数有三个:key、data、mode。key为加密解密使用的密钥,data为加密

解密的数据,mode为其工作模式。当模式为加密模式时,明文按照64位进行分组,形成明文组,key用于对数据加密,当模式为解密模式时,key用于对数据解密。实际运用中,密钥只用到了64位中的56位,这样才具有高的安全性。

des算法/des算法 编辑

算法为密码体制中的对称密码体制,又被成为美国数据加密标准,是1972年美国IBM公司研制的对称密码体制加密算法。

其密钥长度为56位,明文按64位进行分组,将分组后的明文组和56位的密钥按位替代或交换的方法形成密文组的加密方法。

DES/des算法 编辑

分组比较短、密钥太短、密码生命周期短、运算速度较慢。

主要流程/des算法 编辑

des算法
des算法流程图

DES算法把64位的明文输入块变为64位的密文输出块,它所使用的密钥也是64位,整个算法

的主流程图如下:

置换规则表

其功能是把输入的64位数据块按位重新组合,并把输出分为L0、R0两部分,每部分各长32位,其置换规则见下表:

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,

61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7,

即将输入的第58位换到第一位,第50位换到第2位,...,依此类推,最后一位是原来的第7位。L0、R0则是换位输出后的两部分,L0是输出的左32位,R0 是右32位,例:设置换前的输入值为D1D2D3......D64,则经过初始置换后的结果为:L0=D58D50...D8;R0=D57D49...D7。

经过16次迭代运算后。得到L16、R16,将此作为输入,进行逆置换,即得到密文输出。逆置换正好是初始置换的逆运算。例如,第1位经过初始置换后,处于第40位,而通过逆置换,又将第40位换回到第1位,其逆置换规则如下表所示:

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 26,33,1,41,9,49,17,57,25,

放大换位表

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,

单纯换位表(P盒置换表)

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,

功能表(S盒)

在f(Ri,Ki)算法描述图中,S1,S2...S8为选择函数,其功能是把48bit数据变为32bit数据。下面给出选择函数Si(i=1,2......8)的功能表:

选择函数Si

S1:

14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,

0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,

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,

des算法
des算法

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,

0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,

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:

7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,

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,

3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14,

S5:

2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,

14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,

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,

9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,

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:

13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,

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,

在此以S1为例说明其功能,我们可以看到:在S1中,共有4行数据,命名为0,1、2、3行;每行有16列,命名为0、1、2、3,......,14、15列。

现设输入为:D=D1D2D3D4D5D6

令:列=D2D3D4D5

行=D1D6

然后在S1表中查得对应的数,以4位二进制表示,此即为选择函数S1的输出。下面给出子密钥Ki(48bit)的生成算法

子密钥的生成算法

des算法
des算法

从子密钥Ki的生成算法描述图中我们可以看到:初始Key值为64位,但DES算法

规定,其中第8、16、......64位是奇偶校验位,不参与DES运算。故Key 实际可用位数便只有56位。即:经过缩小选择换位表1的变换后,Key 的位数由64 位变成了56位,此56位分为C0、D0两部分,各28位,然后分别进行第1次循环左移,得到C1、D1,将C1(28位)、D1(28位)合并得到56位,再经过缩小选择换位2,从而便得到了密钥K0(48位)。依此类推,便可得到K1、K2、......、K15,不过需要注意的是,16次循环左移对应的左移位数要依据下述规则进行:

循环左移位数

1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1

以上介绍了DES算法的加密过程。DES算法的解密过程是一样的,区别仅仅在于第一次迭代时用子密钥K15,第二次K14、......,最后一次用K0,算法本身并没有任何变化。

DES/des算法 编辑

DES算法具有极高安全性,到目前为止,除了用穷举搜索法对DES算法进行攻击外,还没有发现更有效的办法。而56位长的密钥的穷举空间为2的56次方,这意味着如果一台计算机的速度是每一秒种检测一百万个密钥,则它搜索完全部密钥就需要将近2285年的时间,可见,这是难以实现的,当然,随着科学技术的发展,当出现超高速计算机后,我们可考虑把DES密钥的长度再增长一些,以此来达到更高的保密程度。

des算法
des算法

由上述DES算法介绍我们可以看到:DES算法中只用到64位密钥中的其中56位,而第8、16、24、......64位8个位并未参与DES运算,这一点,向我们提出了一个应用上的要求,即DES的安全性是基于除了8,16,24,......64位外的其余56位的组合变化256才得以保证的。因此,在实际应用中,我们应避开使用第8,16,24,......64位作为有效数据位,而使用其它的56位作为有效数据位,才能保证DES算法安全可靠地发挥作用。如果不了解这一点,把密钥Key的8,16,24,......64位作为有效数据使用,将不能保证DES加密数据的安全性,对运用DES来达到保密作用的系统产生数据被破译的危险,这正是DES算法在应用上的误区,留下了被人攻击、被人破译的极大隐患。

源程序/des算法 编辑

/*在我测试的时候发现这个代码的一个问题是

如果加密后的密文里面有00这个字节的话

解密出来的就会是乱码,编译环境vc6.0

vs2008 使用需注意 */

(名为schedle.h的头文件)

#include

DWORDLONG dwlKey_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,

des算法
三重des算法

63,55,47,39,31,23,1

5,

7,62,54,46,38,30,22,

14,6,61,53,45,37,29,

21,13,5,28,20,12,4,0};

DWORDLONG dwlKey_PC_2={

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,

46,42,50,36,29,32,0};

DWORDLONG dwlData_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,

63,55,47,39,31,23,15,7,0};

DWORDLONG dwlData_Expansion={

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,

28,29,30,31,32,1,0};

DWORDLONG dwlData_P={

16,7,20,21,

29,12,28,17,

des算法
子密钥的生成过程

1,15,23,2

6,

5,18,31,10,

2,8,24,14,

32,27,3,9,

19,13,30,6,

22,11,4,25,0};

DWORDLONG dwlData_FP={

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,

33,1,41,9,49,17,57,25,0};

DWORDLONG OS={

14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,

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,

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,

0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,

13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9,

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,

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,

des算法
基于DES算法的RFID安全系统设计

10,6,9,0,12,11,7,13,15,1,3,1

4,5,2,8,4,

3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14,

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,

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,

9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,

4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13,

des算法
des算法图解

4,11,2,14,15,0,8,13,3,1

2,9,7,5,10,6,1,

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,

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,

2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11

};

------------------------

(以下为主程序)

#include

#include

#include

#include

#include "Schedle.h"

class CShift{

public:

DWORDLONG mask;

int step;

CShift(){

for(int i=0;i<16;i++){

step[i]=2;

mask[i]=0xc000000;

}

step=step=step=step=1;

mask=mask=mask=mask=0x8000000;

}

};

class CDES{

public:

CDES(){

m_dwlKey=0;

m_dwlData=0;

ConvertTableToMask(dwlKey_PC_1,64);

//PrintTable(dwlKey_PC_1,7,8);

ConvertTableToMask(dwlKey_PC_2,56);

ConvertTableToMask(dwlData_IP,64);

ConvertTableToMask(dwlData_Expansion,32);

ConvertTableToMask(dwlData_FP,64);

ConvertTableToMask(dwlData_P,32);

Generate_S();

}

void PrintBit(DWORDLONG);

void EncryptKey(char *);

unsigned char* EncryptData(unsigned char *);

unsigned char* DescryptData(unsigned char*);

private:

void ConvertTableToMask(DWORDLONG *,int);

void Generate_S(void);

void PrintTable(DWORDLONG*,int,int);

DWORDLONG ProcessByte(unsigned char*,BOOL);

DWORDLONG PermuteTable(DWORDLONG,DWORDLONG*,int);

void Generate_K(void);

void EncryptKernel(void);

DWORDLONG Generate_B(DWORDLONG,DWORDLONG*);

/*For verify schedule permutation only*/

DWORDLONG UnPermuteTable(DWORDLONG,DWORDLONG*,int);

/**************************************/

DWORDLONG dwlData_S;

CShift m_shift;

DWORDLONG m_dwlKey;

DWORDLONG m_dwlData;

DWORDLONG m_dwl_K;

};

void CDES::EncryptKey(char *key){

printf("nOriginal Key: %s",key);

m_dwlKey=ProcessByte((unsigned char*)key,TRUE);

// PrintBit(m_dwlKey);

m_dwlKey=PermuteTable(m_dwlKey,dwlKey_PC_1,56);

// PrintBit(m_dwlKey);

Generate_K();

// printf("n******************************************n");

}

void CDES::Generate_K(void){

DWORDLONG C,D,tmp;

C=m_dwlKey>>28;

D=m_dwlKey&0xfffffff;

for(int i=1;i<=16;i++){

tmp=(C[i-1]&m_shift.mask[i-1])>>;(28-m_shift.step[i-1]);

C[i]=((C[i-1]<

tmp=(D[i-1]&m_shift.mask[i-1])>>;(28-m_shift.step[i-1]);

D[i]=((D[i-1]<

m_dwl_K[i]=(C[i]<<28)|D[i];

m_dwl_K[i]=PermuteTable(m_dwl_K[i],dwlKey_PC_2,48);

}

}

DWORDLONG CDES::ProcessByte(unsigned char *key,BOOL shift){

unsigned char tmp;

DWORDLONG byte=0;

int i=0;

while(i<8){

while(*key){

if(byte!=0)

byte<<=8;

tmp=*key;

if(shift)

tmp<<=1;

byte|=tmp;

i++;

key++;

}

if(i<8)

byte<<=8;

i++;

}

return byte;

}

des算法
基于des算法的rfid安全系统

DWORDLONG CDES::PermuteTable(DWORDLONG dwlPara,DWOR

DLONG* dwlTable,int nDestLen){

int i=0;

DWORDLONG tmp=0,moveBit;

while(i

moveBit=1;

if(dwlTable[i]&dwlPara){

moveBit<<=nDestLen-i-1;

tmp|=moveBit;

}

i++;

}

return tmp;

}

DWORDLONG CDES::UnPermuteTable(DWORDLONG dwlPara,DWORDLONG* dwlTable,int nDestLen){

DWORDLONG tmp=0;

int i=nDestLen-1;

while(dwlPara!=0){

if(dwlPara&0x01)

tmp|=dwlTable[i];

dwlPara>>=1;

i--;

}

return tmp;

}

void CDES::PrintTable(DWORDLONG *dwlPara,int col,int row){

int i,j;

for(i=0;i

printf("n");

getch();

for(j=0;j

PrintBit(dwlPara[i*col+j]);

}

}

void CDES::PrintBit(DWORDLONG bitstream){

char out;

int i=0,j=0,space=0;

while(bitstream!=0){

if(bitstream&0x01)

out[i++]='1';

else

out[i++]='0';

j++;

if(j%8==0){

out[i++]=' ';

space++;

}

bitstream=bitstream>>1;

}

out[i]='';

strcpy(out,strrev(out));

printf("%s **:%dn",out,i-space);

}

void CDES::ConvertTableToMask(DWORDLONG *mask,int max){

int i=0;

DWORDLONG nBit=1;

while(mask[i]!=0){

nBit=1;

nBit<<=max-mask[i];

mask[i++]=nBit;

}

}

void CDES::Generate_S(void){

int i;

int j,m,n;

m=n=0;

j=1;

for(i=0;i<512;i++){

dwlData_S[j][m][n]=OS[i];

n=(n+1)%16;

if(!n){

m=(m+1)%4;

if(!m)

j++;

}

}

}

unsigned char * CDES::EncryptData(unsigned char *block){

unsigned char *EncrytedData=new unsigned char⒂;

printf("nOriginal Data: %sn",block);

m_dwlData=ProcessByte(block,0);

// PrintBit(m_dwlData);

m_dwlData=PermuteTable(m_dwlData,dwlData_IP,64);

EncryptKernel();

// PrintBit(m_dwlData);

DWORDLONG bit6=m_dwlData;

for(int i=0;i<11;i++){

EncrytedData[7-i]=(unsigned char)(bit6&0x3f)+46;

bit6>>=6;

}

EncrytedData='';

printf("nAfter Encrypted: %s",EncrytedData);

for(i=0;i<8;i++){

EncrytedData[7-i]=(unsigned char)(m_dwlData&0xff);

m_dwlData>>=8;

}

EncrytedData='';

return EncrytedData;

}

void CDES::EncryptKernel(void){

int i=1;

DWORDLONG L,R,B,EK,PSB;

L=m_dwlData>>32;

R=m_dwlData&0xffffffff;

for(i=1;i<=16;i++){

L[i]=R[i-1];

R[i-1]=PermuteTable(R[i-1],dwlData_Expansion,48); //Expansion R

EK=R[i-1]^m_dwl_K[i]; //E Permutation

PSB=Generate_B(EK,B); //P Permutation

R[i]=L[i-1]^PSB;

}

R<<=32;

m_dwlData=R|L;

m_dwlData=PermuteTable(m_dwlData,dwlData_FP,64);

}

unsigned char* CDES::DescryptData(unsigned char *desData){

int i=1;

unsigned char *DescryptedData=new unsigned char⒂;

DWORDLONG L,R,B,EK,PSB;

DWORDLONG dataPara;

dataPara=ProcessByte(desData,0);

dataPara=PermuteTable(dataPara,dwlData_IP,64);

R=dataPara>>32;

L=dataPara&0xffffffff;

for(i=16;i>=1;i--){

R[i-1]=L[i];

L[i]=PermuteTable(L[i],dwlData_Expansion,48); //Expansion L

EK=L[i]^m_dwl_K[i]; //E Permutation

PSB=Generate_B(EK,B); //P Permutation

L[i-1]=R[i]^PSB;

}

L<<=32;

dataPara=L|R;

dataPara=PermuteTable(dataPara,dwlData_FP,64);

// PrintBit(dataPara);

for(i=0;i<8;i++){

DescryptedData[7-i]=(unsigned char)(dataPara&0xff);

dataPara>>=8;

}

DescryptedData='';

printf("nAfter Decrypted: %sn",DescryptedData);

return DescryptedData;

}

DWORDLONG CDES::Generate_B(DWORDLONG EKPara,DWORDLONG *block){

int i,m,n;

DWORDLONG tmp=0;

for(i=8;i>0;i--){

block[i]=EKPara&0x3f;

m=(int)(block[i]&0x20)>>4;

m|=block[i]&0x01;

n=(int)(block[i]<<1)>>2;

block[i]=dwlData_S[i][m][n];

EKPara>>=6;

}

for(i=1;i<=8;i++){

tmp|=block[i];

tmp<<=4;

}

tmp>>=4;

tmp=PermuteTable(tmp,dwlData_P,32);

return tmp;

}

void main(void){

CDES des;

des.EncryptKey("12345678");

unsigned char *result=des.EncryptData((unsigned char*)"DemoData");

des.DescryptData(result);

}

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